MIT Electric Vehicle Team Blog

Video of eSuperbike at the Isle of Man

2011-09-20T21:17:00.002-04:00

I Believe I Can Fly . . .

2011-06-29T11:35:00.003-04:00

Check out the rest of the posts below to see the history of this project, start-to-finish. If you think that what we're doing is cool and would like to help us 'touch the sky' on our next build, we kindly accept your support. This helps us with everything that the main sponsors can't provide, such as random electronic components, specialized tools, equipment for our shop, flights to our events, etc... Secured, tax-deductible and handled by MIT, the link is here.

Isle of Man - Day 15 - Thank You!

2011-06-14T06:10:00.014-04:00

The race is over, eSuperbike is packed up and waiting to be shipped back to Boston, and the MIT Electric Vehicle Team members have split off in all directions towards various summer adventures. The experience of building an electric motorcycle and racing it at the Isle of Man was amazing. The words and pictures here truly don't do it justice. Before we sign off and this blog goes quiet again for a while, the team would like to say thank you to our sponsors over the two years of this project.

THANK YOU...

...to BMW for the motorcycle frame, and even more so for the CAD files which allowed us to design the bike electronically before any parts were actually fabricated.

...to A123 Systems for building a custom battery pack to our specifications; for countless e-mails and phone calls as we trouble-shot our system and tweaked it for racing; and for coming to the rescue when we realized that only you had the paperwork needed to ship our batteries to the Isle of Man. In particular thank you to Yet-Ming Chiang, Brian Moorhead, Jerry Gohl, Doug Moorehead and Mobashar Ahmad.

...to Rahn and Mark at Rahn's Motorcycle Engineering for hours of time on the dyno without which we never would have understood our motors; and for the general support and encouragement of the team. Their relentless support was extremely encouraging and kept us going during rough times.

...to the MIT Energy Initiative, Transportation @ MIT and the MIT Mechanical Engineering Department for extensive financial support.

...to The Edgerton Center for an incredible workspace, access to tools and equipment and your general support of student teams at MIT. (the picture is of our bike in the back of the Edgerton Center pickup truck)

...to the Singapore University of Technology and Design (SUTD) and the International Design Center (IDC) for general support of student groups and new initiatives. Thank you in particular to Pofessors Dan Frey and Sanjay Sarma for your long term commitment to the project.

...to Derek, Scott and John at Boston Moto for the opportunity to test our bike during their track day at the New Hampshire Motor Speedway, and for your technical support and introduction to the world of motorcycle racing.
...to Mark at TurnOneGraphics.com for all of the extra work you put in to make our graphics look so good, and for your support and advice during our track day in New Hampshire.

...to Dave at Evomoto in Ramsey for always fitting us in for those final dyno sessions as we kept rebuilding our motors in the days leading up to our race.

...to the following companies for advice and equipment support as we brought our project to completion:
- KillaCycle Racing
- Kelly Controllers
- Boulder Electroride
- Woodcraft
- Lynch Motor Company
- Sharkskinz

Last but certainly not least, THANK YOU...

...to Allan Brew for piloting eSuperbike around the course safely (and faster every time), allowing us to take over your garage as a workspace, and generally introducing a bunch of newbies to the world of the Isle of Man TT.
...to Jan Brew for your wonderful Manx hospitality and English tea, and for allowing us to both take over your kitchen and send your husband out for more stress-inducing laps of the TT course.

From me personally, it's been an incredible ride both literally and figuratively. Thank you to the rest of the MIT Electric Vehicle Team for your hard work on the project both before and after I showed up on the team (Will, Manyu, Brent, Dianna, Dan, Romi and Mateo), flexibility when the team made tough decisions (Erick), dedication when the typical time constraints of MIT kicked in (Randall), focus when the going got tough (Radu), and for vision in the early days, innovative technical ideas in every aspect of the bike and relentlessly keeping the team on track (Lennon). It's been great working with you and we should all be proud of what we accomplished.

-Mark

Isle of Man - Day 13 - Race photos

2011-06-11T15:16:00.008-04:00

The weather was better on the postponed race day (Thursday), and the team drove down to the grandstands for the race at 3:30. Then the race time was shifted again, not weather this time, but because of shifting the order of events. So we waited.

Eventually, it was certain that the race would go off at 5:15. Nine teams went through tech inspection and set up in parc ferme.

eSuperbike received its' third and final tech inspection sticker.

Once again teams had a chance to wander among the machines (well, among the ones that weren't in their own little tents anyway).

Photographers roamed around snapping pictures of bikes...

...and teams.

Allan was interviewed on local radio.

Finally, at about 5 o'clock, the marshals let us up onto the track to the starting grid.

Once again the bikes lined up in order and were sent off at 10-second intervals.

No wheelies here, just a smooth start down Bray Hill.

And then we waited.

By this time we had discovered the TT Live website, where we could track bikes as they pass certain checkpoints on the course. The iPhone came out as soon as Allan was out of view.

Something got jumbled though, and Allan was listed as riding through the Sulby Speed Trap at 102mph, which is faster than eSuperbike was allowed to go! We'd limited the motor controller voltage in order to protect the motors, so something must have been wrong with the course's timing system or our transponder.

Or was something wrong with the bike? If Allan was actually going that fast, then the motors were sure to burn up and fail and we'd be out of the race. But nothing's gone wrong like that before. But why is the number so high? All we can do is wait.

We could tell from the website (watched from an iPhone) that a couple of the teams didn't make it through certain checkpoints. On a 37.73-mile course, the worst part about watching a race is the limited information you can get about the bike and rider while they're out on the course. But Allan's name kept showing up on the screens for each checkpoint: Ramsey Hairpin, The Bungalow, Cronk ny Mona...

And then we finally saw them.

Fouth place!

Allan did the course in 28 minutes and 35 seconds, with an average lap speed of 79.1 mph. He and eSuperbike were faster every time they went out on the course.

The team was all smiles when he came back through the pits.

Lots of congratulations all around on a job well done.

Congratulations to MotoCzysz for taking first and second place, and to Kingston University for third place and the university prize.

The most surprising outcome of the race was MotoCzysz not getting the 100mph lap. Their two bikes drafted off of each other for most of the race to save energy, but the faster of the two only managed a 99.6 mph average. So close! There is a GBP 10,000 prize for the first electric bike to break the 100mph barrier, and it's still up for grabs.

-Mark

Isle of Man - Day 13 - Fourth Place!

2011-06-09T14:51:00.004-04:00

Final stats:

1st place - Michael Rutter - Moto Czysz
2nd place - Mark Miller - Moto Czysz
3rd place - George Spence - Kingston University
4th place - Allan Brew - MIT
5th place - Yoshinari Matsushita - Prozza

32 - teams entered
16 - teams confirmed
5 - teams qualified
9 - teams started (including teams who did not meet official qualifying standards)
5 - teams finished

The team is very happy with the result. We were the fastest first-time entrant and one of only four bikes to complete both qualifying laps and the race.

Photos coming soon!

-Mark

Isle of Man - Day 12 - Race Postponed

2011-06-08T16:27:00.007-04:00

The 2011 TT Zero race was scheduled to run today, but got postponed (along with the other two races that were supposed to run today) to tomorrow due to bad weather on the course. Race officials started an earlier race (Supersport 2) despite riders' protests, but then stopped it due to worsening weather conditions. Finally, at about 2pm, just as the TT Zero bikes were scheduled to go into technical inspection, the announcement came over the loudspeakers at the grandstands that all further races for the day were postponed to tomorrow.

We were disappointed of course, though some teams are probably relieved to have another day to get the kinks out of their machines. We loaned the ManTTX team a set of motor rotors, so hopefully they'll be ready to run tomorrow. There is still a question as to who will actually be eligible to win an award, though. Of the nine electric motorcycles that started in the practices, only five completed the required qualifying lap. Race organizers, however, have stated that any electric bike that is running will be allowed to start the race. No official comment has been made on who will or will not be eligible to receive an award though. Similar situations came up in the first two years of the TT Zero, so we'll see how it's handled this year.

That is one of the big issues of testing new technology in a race setting... going faster always invites the risk of not making it all the way around at all.

Yesterday we pushed hard to have the bike ready by the evening. Monday's practice showed us that a plastic component (the brush holder) of the motors contributed to them getting out of balance with each other. That plastic part was a new development though... we still had spares of that part from older motors which were made of FR4. While more expensive, FR4 handles the heat of the motors much better than plastic and wouldn't allow the motors to get out of balance as quickly. So we decided to swap out the brush holders with the older part, so Radu went back into beast mode.

In the meantime, Erick worked on waterproofing some of our electronics.

Randall arranged for an improved data logging system.

This morning we did a little bit more waterproofing...

Here you can see the black tape on the sides of the frame to help keep moisture away from the electronics and cables.

We're pretty sure that we can handle any rain or wet-road conditions in which race organizers would actually start a race. Weather on the island is unpredictable and very local though, so it's never possible to predict exactly what the other side of the course will be like when you start.

Finaly prepping and cleaning in the garage...

...and then it was time to load up into Allan's van.

We piled into cars to drive the ~30 minutes to the grandstands, and heard on the radio on the way down that the Supersport 2 race had been stopped mid-race due to weather. Once at the paddock, we didn't even bother unloading the bike or any tools. Half an hour later it was announced that we wouldn't race today.

In anticipation of posting a blog about a successful race tomorrow, here are some photos of the grandstands and start/finish area.

From the main grandstands... the view of the start/finish line and results boards.

The main leader board. The stands in the foreground are to hold up the quick-fill fuel tanks for the gas bikes.

Map of the course and the results board. Under each entry number you can see a dial with points for Glen Helen, Ramsey and Bungalow to indicate where on the course that rider is.

I expect these stands to be completely full tomorrow.

View of the paddocks from the top of the grandstands. This is only maybe one tenth of the team paddock space.

As soon as the course was opened up after the cacellation of the rest of racing, the pit lane turned into motorcycle parking.

-Mark

Isle of Man - Day 10 - Qualifying #2

2011-06-06T23:20:00.014-04:00

With Erick's arrival from Boston (he graduated last weekend), the entire team is now on the island. It's been an intense weekend with motor rebuilds, dyno time and conversations with the ManxTTX team about their experience with the same motors. We've learned a ton about the motors and how they fail, and every new piece of understanding increases our chances of keeping the motors running optimally through to the end of the race on Wednesday.

Our day started with another run on the dyno to confirm our motor settings.

Back at the garage, Radu noticed that the motor gaps were off. Each motor has a core (or armature) that spins between two sets of magnets. If the gaps between either side of the armature and its respective set of magnets are different from each other, then the motor isn't going to run well. Radu's discovery this morning led us to believe that running the motors on the dyno cause them to heat up too much and allows the armature to shift in the housing. If it shifts too much, the armature will contact the magnets on one side, leading to complete loss of power (in the best case) or full motor failure where the armature is destroyed beyond repair.

We discussed our options...

...and decided that the best course was to re-shim the culprit motor to get the armature centered between the magnets again.

Randall worked more on stickers.

Lennon took the bike out for a quick spin to confirm the fix. With a larger sprocket on the back wheel, he got noticeably more acceleration out of the bike. To get that though, we had to give up a bit of top end speed. The qualifying lap today would help us determine the best sprocket choice for the race on Wednesday.

Allan had his Supersport (gas bike) race early this afternoon, then he came back to Ramsey to pick up eSuperbike. We all piled in and followed him back to the start/finish line.

Through inspection and in parc ferme, we put tyre warmers on and got the chance to chat with folks about eSuperbike.

Motoczysz, last year's winning team, had both bikes out today.

It may have just been for the cameras, but it looked like Michael Czysz was introducing the rider to the controls on the bike for the first time here.

Unlike last Saturday, the bikes were started from the official start line out on the track today. Lennon took eSuperbike up to the starting grid and Allan took it from there.

The team.

The bikes start just before the grandstand and the pits.

Ready and waiting for the start. The bikes go off one at a time on the course, so everyone lines up single-file to wait for their turn.

Sitting and waiting for your bike to come back around the track is pretty stressful. You go through all of the possible scenarios of what can go wrong from the motors to the batteries, the chain to the rider to the weather. In the first two years of the electric racing, lots of bikes broke down along the way. You just hope that you won't be another one of them.

And then your bike comes into view.

So how'd we do? Allan finished with a time of 28:50, or an average lap speed of 78.5. That's faster than Saturday's run, but still a bit behind the top three teams.

It might have been all the bugs that slowed him down. =)

So we're qualified twice over, and still tweaking the bike for a bit more overall speed. We collected quite a bit of data today which we'll go over with Allan tomorrow and use to decide the final settings for race day on Wednesday. As always, it's a battle of how far we can push the motors and still be certain to get all the way around the course.

I got a request for more landscape pictures of the island. It really is beautiful here. Most of these are taken from moving cars, but they give an idea of what it's like here. I think of it as being on a 25-mile-long ship in the middle of the ocean, since the weather changes so quickly, you get plenty of breezes off the water, and the sun feels strong because of the clear air.

The harbor in Ramsey. The boats are built to sit on dry land when the tide goes out.

We've seen lots of coastline, especially with the mountain road closed for racing (the mountain road is the faster way to get between where we're staying and the capital city of Douglas).

Lots of motorcycles around, of course. They've arrived by the ferry-load for the last week from all over Europe.

Sheep in the fields.

Another type of local fauna during the TT: traffic police with speed radar guns.

-Mark

Isle of Man - Day 8 - Qualifying

2011-06-05T15:50:00.016-04:00

Saturday was our first chance to qualify for the TT Zero race on Wednesday. The demands were fairly low, we only needed to attain an average speed around the course of just under 50 mph. Our strategy was to dial back the motor controller to a lower setting that we were totally comfortable with so that we could let our rider go full throttle as much as he liked and we would not be anywhere near the limits of our motors.

The bike was essentially all set to go, so we spent the morning taking care of a few last details and getting the bike all ready with the decals.

The top fairing ended up looking a lot better once we put a few of the decals on. They definitely help to hide the irregularities in the shape.

Allan put on the transponder that we need for the race. This will allow the sector times to be automatically logged as the bike makes its way around the course.

Once we arrived at the grandstands, we had to wait for a while until the scrutineers were ready to inspect our bike. Next to our bike, on the left, is the bike from Kingston University. It seems like a very competitive bike with a YASA 250KW motor with 500 Nm of torque. Apparently, the bike runs of off a "flux-capacitor" battery according to the team leader (this is race terminology for "you don't need to know what our batteries are").

Our bike got a careful looking over for any mechanical problems or interferences that could be a safety hazard out on the course. The men in blue are the so-called "scrutineers."

After passing inspection, we proceeded to the parc ferme where the bikes wait until the beginning of the practice session. We put on the tire warmers right away so that they would have sufficient time to heat up before going out on the course. This is important to soften the rubber and maximize the grip.

While the tires warmed and we waited to be called up to start, Allan was interviewed by Chris from Manx Radio, one of the local stations.

After about 45 minutes, we were called to start and Allan took the bike up to the starting line.

Last year's winner, Motoczysz, showed up just as the bikes were being called up to start. Here, Michael Czysz pushes their new bike up to the starting line. Their team is certainly quite professional (notice the matching black Nike shoes).

Here is a nice side view of Motoczysz' sweet new bike.

One unique aspect of the Isle of Man TT compared to a track race is that once the riders take off, you don't see them for another 20 minutes or so as they complete a lap (or in the case of the electrics, closer to 30 min). We gathered in one of the buildings where they have updates on a screen and watched as the riders came through the Sulby Straight. Motoczysz clocked a very impressive 142.8 mph through the straight, followed by Kingston University with 96.1 mph (obviously dialed way back from what they are capable of), and MIT with a respectable 91.2 mph, which is almost exactly what we expected based on our testing and calculations.

Of the six teams that were at the practice session, only four finished. We were happy to see Allan as he crossed the finish line with a pump of the fist. He completed the course in 29 minutes 54 seconds, which works out to an average speed of 75.7 mph.

Once the practice session was over, we took a few temperature readings off the bike, gathered the information from the microcontroller, and headed back to Allan's home.

Isle of Man - Day 6.5 - Noise from the motors

2011-06-03T01:49:00.005-04:00

(By Lennon)

Mark had left by the afternoon (he's gone until Sunday - friend's wedding in Germany), and we were just about to kick back, relax, and wait for the first qualifier/practice on Saturday. We've had an intense week, but everything has checked out just as planned.

But I wanted to do one more speed test to ensure some adjustments we made to the motor controller were effective. Initially I was going to just go by myself - just a few quick passes at 100MPH out on our country road circuit. But Radu ended up catching a ride with Allan's friend - since it wouldn't hurt to have some tools out there and an extra person just in case.

When I was doing my final 100MPH pass I noticed a very faint rubbing noise when I was manually pushing the motorcycle to turn it around. I am so sensitive to noise when riding the bike, and it was clear that something was wrong. Hopefully just a fairing rubbing or something.

So I slowly rode the bike back to Radu and he crawled around the bike with his ear and hands as close as possible to the various parts of the bike. I (in full rider gear/helmet/gloves) rolled the bike back and forth over the point where I heard the noise. Radu was equally puzzled. It was very faint, but there. With 100MPH speeds and 32kW of power, a small rubbing at low speeds could domino to extreme rubbing at high speeds when centrifugal forces and heat can cause items to expand. The expansion would make the rubbing increase, the point of contact would get hotter, make it expand more... u get the point - it's a runaway affect that is an engineer's nightmare - totally uncontrollable and would happen very fast. The motor would likely overheat, melt, and the rider would hopefully feel the drop in power and be able to decelerate before the motor completely tears apart.

There are two things spinning on this bike, and they spin at different speeds/frequencies: (1) wheel and (2) motor. First Radu had to figure out if it was caused by the wheels rubbing (maybe on the fairings, etc.). Nope, the rubbing didn't occur at the rate of one tire revolution. Now to the motor. Move the bike and watch the motor shaft. Yep, we heard the noise every time the motor spun around once. So it's something in the motors.

Radu is a wizard, and he has spent a lot of time with our motors - going all the way back to the dyno tests which started in February. He worked with ninja precision - and noticed the gap between the rotor (rotating part of the motor) and the magnets (stationary part) were extremely close. He grabbed a few wrenches to see if some of the internal bolts were loose. They were!! The noise went away when we tightened the bolts. This was a fault of the motor manufacturer, and so is the rubbing. It shouldn't do this. Thus in conclusion: (1) the gap between the rotor and magnets was incorrectly set in the factory - it's too small (the gaps on both sides of the rotor should be the same, but it is not). (2) the motor manufacturer didn't tighten the rotor bolts properly - and they slowly worked their way loose over the last few months. The lack of a gap and loose bolts were causing the rubbing noise - we were pretty sure.

So I drove slowly back to the shop, while Radu and Allan's friends followed. I wanted to repeat the noise: we loosened the bolts - the noise returned. We tightened the bolts and the noise went away. OK - conclusive - that's the problem.

So what do we do? Our options:

1) Ignore it - might not be an issue now that the bolts are tight. Risk: the small gap might make the motors over heat and rubbing could cause thermal runaway (as described above).

2) Replace the motors (we have spares). Risk: this requires a total bike rebuild due to how our motors are bolted to the frame. Taking the bike completely apart two days before our qualifier is riddled with land mines.

3) Rebuild the faulty motor. We can do this with the motors left on the bike (i.e. we don't need to disassemble the bike). Risk: we've never done a full overhaul rebuild. Do we have enough time to ensure the motors are properly working after the overhaul? If something goes wrong - we'll have lost precious time and it would be a rush to swap in a new motor.

None of these seemed like great options. Each with their own risks/uncertainties.

In the mean time we went and chatted with a local Manx team who is racing for the third year. They've had these motors blow up before - and might have good advice.

After much deliberation, we decided to go with #3 = rebuild the motors. If we couldn't pull it off in the few remaining hours of the night, then we'd make a go-/no-go in the morning. We would then have to rush to pull off #2.

So Radu started taking the motor apart. One thing you should know about Radu. He is - what we call in engineering - a beast. He works best under high pressure and risk. Extremely powerful if contained. He's the guy you want on the airplane if it's going down with one minute to spare. He'll figure out some way of strapping himself and other parts to the wing - or whatever - to ensure the plane banks, dives, etc. into a fairly safe landing. When he's in "beast" mode, his eyes become large, he becomes quiet/focused (though he might blare out a classic rock song lyric or two on occasion), and you can tell he's in an arena where he thrives. By picking #3, I knew the Radu beast would come out to play.

And it did - here he is working on the motor:

With the motors open it became clear that we likely just avoided a catastrophe. Very little to no damage to the motors, so we must have caught it the instant it started. It is unlikely that Allan would have heard the noise - since he only knows one throttle position (full), and is not sensitive to the noises (since it might sound normal to him).

Some pics of the motor as we took it apart:

We removed three shims that were on the inside of the rotor on the shaft. This should balance out the gap on both sides of the rotor.

Motors have very strong (rare earth) magnets, and it's a very delicate/tricky procedure. As the outer stator cover (magnets) are brought in close to the disassembled motor (as shown in the pic above), the entire assembly wants to crush in on itself because of the magnetic forces. If your fingers are in between they'll certainly be crushed and possibly removed free of charge. I busted out a wood saw and cut three wooden wedges to slowly bring the outer stator into contact - hopefully flat, level and in control/steady. After a few modifications - and a bit of the Radu beast - the motor came back together.

When we decided to rebuild the motor, our conditions were that it would need to go back on the dyno for a full pack, full power test. If it passes, we'll fully recharge the pack (4 hours), and go out on the road for testing in the afternoon/evening. If it doesn't pass... we have a dilemma.

We were in bed by 1:30AM. I woke up at 6:30AM to come back to the shop and charge up the bike. Due to another incident (which we fixed), I didn't feel comfortable letting it charge over night.

Let's hope we can obtain access to the dyno & the repaired motor passes the test.

Isle of Man - Day 6 - The Big Debate

2011-06-02T12:03:00.005-04:00

Today has been relatively unexciting compared to the past couple days. The bike is running well, and we only have a few things to adjust in regards to actually having the bike ready to run in the qualifying session on Saturday.

We had some issues with the upper fairing flexing, so Radu added steel stiffeners to the inside.

It wasn't pretty, but the clamping setup did the job.

I worked on getting the modified sharkfin into position. In case you were wondering, it's nerve-wracking to take a drill to the swingarm of your motorcycle.

Installed, the shark fin will protect the rider's left foot and keep it from getting caught up in the chain and rear sprocket.

Allan had some more work to do on his Kawasaki (or Kwacker, for short).

Reinforcements in place, Radu had to push a bit to be ready to have the fairing painted.

He added a layer of fiberglass (fibreglass) over the sheet metal, and it's just about ready for painting.

Allan and Jan have been wonderfully helpful. This is what their kitchen table look like with all of our computers (though one of them belongs to Allan). That's Allan's jacket from the 2007 TT.

Lennon and Randall worked on the software side. With the bike running well, we'd like to add datalogging to the system to help us troubleshoot any problems that come up later on. Ideally we'd add in a GPS unit and transmit data in real-time via the 3G wireless network while Allan is out on the course.

Ever wonder how we got all this gear here? A lot of the smaller electronics arrived in Lennon's suitcase.

Interfacing the datalogger with the two sources of data (the battery control module from A123 Systems and the off-the-shelf 'cycle-analyst' unit) proved tougher than expected.

The workshop/garage hummed this morning, though there wasn't a sense of a huge rush to get something done and meet a deadline.

Breaking for lunch. Mmmm... microwave Indian food. We finished up "Charge", so now we've all seen the whole film and have an idea of what to expect. And a healthy respect for what can go wrong... four teams blew up their motors the first year!

The town of Ramsey, as viewed from the driveway to the cottage where we're staying.

We're now at that point in the development of any design project where we have to decide how much to futz with it. The bike is running well, but we have a short list of 'nice to haves' that we could work on. So we have to balance the risk of messing something up while we work on adding something that we don't technically need in order to be ready for Saturday's qualifying session. They're tough decisions, but I think we made the right choice in staying conservative and not trying to do too much.

It doesn't feel natural to have nothing (or very little) to do on the bike, but it's a lot better than trying to scramble and get it finished at the 11th hour.

So what's left? The suspension needs some minor adjustment to get it to Allan's liking. The fairing is off getting painted, so once it's done we'll need to apply sponsor stickers. Randall and Lennon are adding an on-board datalogger to take data just on the batteries. We're leaving off the cycle-analyst data and the real-time transmission for now. We'll take it out for a speed run this afternoon to confirm the changes we made to the controller electronics, and then comes the hardest part: sitting, waiting, and leaving well enough alone. Our first qualifying session is Saturday at 17:30 BST.

-Mark

Isle of Man - Day 5 - Allan, meet eSuperbike

2011-06-02T01:47:00.008-04:00

"An oasis of insanity in a world of health and safety regulations." - Charge [describing the Isle of Man TT]

A new movie came out only a couple of weeks ago about the TT Zero electric motorcycle race. It's called "Charge" and features narration by Ewan MacGregor. It tells the story of the first two years of the electric race, and we've watched the DVD at least three times now. Click here for the trailer:
http://chargemovie.com/

More bike work this morning in Allan's garage. Lennon worked on the tail lights as required by the rules.

Randall cranked away on software.

I worked on swapping out brake lines. The rules have a specification which disallows the original brake lines on the bike. So we had to swap them out with custom lines. Derek at Boston Moto helped a ton on getting those lines in.

Radu worked away on the upper fairing. Not a bad paint shop, is it?

Lots of sanding.

And a bit of fun with rattle cans.

Lennon working on the lights.

Lunch break, watching more of "Charge". Randall is seeing it for the first time, so we're fitting it in where we can.

Back at the garage, Allan made some adjustments to the fairing on his gas bike. He was going so fast that the rear tire expanded and scraped away the back part of his fairing.

I made some progress on stickers. Mark from TurnOneGraphics.com was a huge help on that one.

Our race number is still covered up, but the stickers look great so far.

We had to make an adjustment to one of the parts on the bike, so I got to do a bit of milling at Allan's workplace.

Lennon got the taillights finished (and flashing)... not bad, eh? And visible from 10m away, just as the rules state.

With more of the bike finished, we put it in Allan's van to take down and talk to the scrutineers.

Allan gave us a tour of the east side of the island as we rode down to Douglas and the start/finish line.

The view on the way down was pretty idyllic.

Pushing the bike through the crowd, our bike got a fair bit of attention.

The chief scrutineer for the electric race looked things over, and was happy with what he saw.

We got a bit of interest while we were there, and even heard one person comment that "the electrics are looking better every year."

Heading back out of town, we passed by the Isle of Man Electric Tramway station. Who knows... maybe we can work out some sort of publicity thing to get the electric bike transported by the electric railway to the start of the race. :-)

Scrutineering makes a student hungry, so guess what we stopped for fish and chips.

Finally back from scrutineering, it was time to give Allan a chance to take eSuperbike out for a ride. We went back out to the same testing spot from yesterday. We hadn't realized it before, but you can see part of the TT mountain course from there. Allan even said he could see a bike running up the road.

Lennon rode the bike out to the testing spot, then handed it over to Allan.

Allan, meet eSuperbike. eSuperbike, meet Allan. Now play nice, boys.

This was my attempt to snap a photo of Allan as he rode past (he was just going too darn fast). Maybe with a couple more passes I would have gotten the timing right.

No, we don't look like hoodlums, do we?

I'm working on posting videos, but we'll see how they turn out. Allan came back with a smile on his face, and said he really enjoyed the bike. He's looking forward to the race, and we're all looking forward to getting him there.

- Mark

Isle of Man - Day 4

2011-06-01T08:58:00.008-04:00

Isle of Man - Day 4

Things are moving fast now. Including our bike. :) These are all from yesterday, but I hope to get a few more from today up later on.

Allan had a good practice on Monday night. The session was flagged right towards the end due to bad weather on the mountain part of the course, but Allan still got in two official laps.

Here he's going through scrutineering before his practice session. Race officials check over his bike to make sure it's safe to ride on the course.

Waiting in the Parc Ferme for his race. Lately Allan's ridden mainly classic bikes, so he's still adjusting to the speed of a modern 600cc superstock bike.

I'd say he's doing pretty well... he hit 143mph at the Sulby Speed Trap the first time around the course.

Coming back through the start/finish area he clocked 136.6mph. That's faster than I've ever been on a motorcycle.

Allan ran another practice session last night, and now he's got four laps under his belt. His second lap would have been at an average of over 110mph if he hadn't slowed down behind a rookie rider towards the end. We've come up quite lucky to find him, as he's got the right combination of ability on the faster modern bikes (with wider tires like our bike) and experience on classics which have a similar power output to eSuperbike.

We also picked up a new set of race tires (tyres) while we were in the paddock.

Back in Ramsey, the guys have been working hard. We finally got the bike out for a test run after lunch. Lennon got suited up in one of Allan's old riding suits for the practice.

Allan suggested heading out to some quiet roads on the north part of the island where he sometimes tests his classic bike. The road had some nice bends in it, and allowed us to ramp up the speed quite a bit.

We got a bit of video too... take a look at youtube for that.
http://www.youtube.com/user/lennonrodgers#p/a/u/0/ax6KNE1eZx4

After a few runs, Lennon handed over the controls...

...and I was so excited to get on the bike that I left my (non-riding) boots on the side of the road.

It was only a little taste of what it must be like on the course, but to scream past tall green hedges like that was pretty cool. Lennon and I both remarked on how we could see this getting addictive.

We topped out the session at 103mph and the bike did great. Our motor temperature readings were a different from each other, which caused a bit of concern. We hit full power though, and everything held together just fine.

This is what it looks like when a couple of guys go grocery shopping for food for four guys. I think this will last us for maybe three days, if that.

A reporter friend of Lennon's had arranged for us to meet Dave Roper who, until last year, was the only American to have ever won a race at the Isle of Man (last year Mark Miller won the electric race).

He and Lennon got a photo op with Dave on an old Indian motorcycle from the very early 1900's.

Back at the garage, Radu cranking away on the fairing.

And then back out on the roads to try and answer that motor temperature question.

The goal was to heat up the motors again and take measurements. We did such a good job that the bike didn't have quite enough juice to make it back to Allan's house. We were less than a mile away though, so the pickup was pretty easy.

Gotta run again... we're heading off to the start/finish to meet with the chief scrutineer for the electrics. We won't officially go through scrutineering until just before our qualifying session on Saturday, but we don't want any surprises at that point.

-Mark

Isle of Man - FAQ

2011-05-31T13:30:00.004-04:00

FAQ

Here are some answers to the most common questions we get asked about the bike and the project...

Why the Isle of Man?
- The Isle of Man TT (it stands for Tourist Trophy) is the oldest and probably best-known motorcycle road race in the world. It started in 1907, and exists in large part because the Isle of Man government has written laws to allow road closures every year for the event. Two years ago a zero-emissions division was introduced, now called the TT Zero, which offers an opportunity for electric motorcycles to compete on the same course. So in other words... why not?
More info here.

Who will ride it in the race?
- The TT rules restrict who is eligible to ride in the TT Zero. Not only does our rider have to have an FIM racing license, he also has to complete six laps of the course in practice before our race. The electric bikes only have two practice sesions of one lap each though, so to get those six laps he has to run at least four laps on a gas bike. The organizers of the race put us in touch with Allan Brew, who lives on the island and has ridden in both the TT and the Isle of Man Grand Prix races (held every fall). He's been a huge help so far, settings us up to work in his garage and helping out with logistics.

How fast will it go?
- We've run the bike at 110mph on the dyno, and hit about 80mph during our track day. We're playing with the gearing though, so that number might change.

How far will it go on a charge?
- The TT course is 37.7 miles long, so we designed the bike to go just a bit further than that under race conditions. If you were only cruising at a constant highway speed, though, the bike could easily go 100 miles.

Does it have tons of torque off the line because of the electric motor? Can you do burnouts/wheelies?
- In theory yes, the motor produces maximum torque at low rpms. Speeds on the TT course are very high though, so we've geared the bike more for that top end. That plus the weight of the batteries on the bike means that we won't be doing any wheelies or burnouts. Our bike will still get off the ground though... there are a couple of spots on the TT course that consistently send the bikes flying (as long as they're going fast enough).

How much power does it have?
- Comparing the power of an electric motor to that of a gas engine is always a bit tricky, as the numbers mean different things. Our motors are rated for a continuous output of 16 kW each, and we have two. 32 kW comes out to about 43 HP. We can get more than that for brief stints ("peak power"), but that risks damaging the motors.

How big is your battery pack?
- Ours is a custom-designed pack from A123 Systems with 12kWh capacity at 100V.

-Mark

Isle of Man - Day 3 - dyno, fairings and wheels

2011-05-30T14:04:00.007-04:00

Isle of Man - Day 3 - dyno, fairings and wheels

We got the bike on a dyno this morning... it was a chance to get the motors up to speed and make sure there were no issues in our last rebuild.

Dave at Evomoto has a nice clean shop, and got us in and out in about 15 minutes.

Here's what our power curve (HP vs. speed) looks like. This is one of the features inherent in electric motors... constant torque.

Back in Allan's garage, we started working on the upper fairing for the bike. We got it set up while in Boston, but we still had to get it off of the mold and do some tweaking to get it to fit right and look good.

Lennon and Radu experimented with different tools to get the foam mold out of the carbon fiber shell.

Allan's wife Jan kept us supplied with English tea while we worked.

Allan also worked on his bike... he has his first practice session on the mountain course this evening. In order to ride in the TT Zero (our race), Allan has to complete 6 laps of the course. At least one of those laps has to be on our bike, but there are only two practice laps scheduled for the electrics. That means he has to ride a gas bike for at least four laps, which means signing up for one of the gas races.

Radu, working away on that foam. He eventually found a good technique involving a hack saw blade, putty knife and elbow grease.

Checking the fit on the upper fairing. Still a ways to go.

Even with the fairing only half-mounted, our rider Allan wanted to check it out.

It feels great to have our rider and bike together. Now we just have to get them out on the road for some practice!

I'll write more later about where we're staying, but this is the view.

Lennon taking a quick snooze over lunch.

To take the bike out for testing on public roads, we have to cover up our race number.

We also have to swap out tires (tyres), so I got to put our new front stand to use.

Allan polishing up his bike for the practice this evening.

We have to extend the top fairing on one side, so Radu improvised on the mold release...

...with cooking spray.

We've been talking about gear ratios since our track day earlier in May (more on that later), and finally decided to give up a bit of top speed in favor of better acceleration. We'll see how Allan likes the slightly larger sprocket we put on.

Right now Radu is still working on the upper fairing and Lennon and I have come down to the start/finish to help Allan with his practice session, meet some folks here and hopefully see some of the other electric teams. It's getting exciting!

-Mark

Isle of Man - Day 2 - assembly

2011-05-29T05:11:00.000-04:00

Today was a boring day for spectators (and I imagine for blog readers). We didn't make it out to the test track since the timing didn't work out and we wanted to recondition the motors.

Allan had a racers meeting and sign-on session at the start/finish early this afternoon, so we're all signed up with three team pit passes. We'll get some more team passes just for the paddock area, but are limited to three people in the pits with the bike (and fire-retardant overalls).

The morning started with mounting battery modules numbers 3 and 4. We had to undo some of our work a couple of times to re-route cables, but it all came together in the end.

This is the mess of cables that we have to fit to, around and through our various electronics, batteries and frame.

Lennon and Radu mounting electronics.

Radu is really getting into the whole English tea-drinking thing.

We sent our tools and lots of spare parts along with the bike so that we have everything here. But, of course, there's always something we still need (luckily we have two more team members traveling from the US next week).

Checking the battery voltage (and making sure we don't have any potential going to other electronics or to the frame) before plugging in the batteries for the first time.

Radu spent a lot of time getting the motors reconditioned, from blowing out dust to sanding down the commutators. Here are the brushes, just about ready to go back into the motors and get seated.

I spent a bit of time building a flashing LED assembly for the rear of the bike.

Lennon working on some programming.

Comparing the current draw of each motor to make sure they're not fighting each other.

A small piece of excitement happened during the day... Lennon blew up an American power strip when he plugged it into a wall here. The switch on it apparently can't take 220V. :-)

-Mark

On the Isle of Man - Day 1

2011-05-28T04:40:00.011-04:00

And now for a report on what's happening on the Isle of Man. Our bike was scheduled to arrive on Friday, 27 May, so Lennon arrived on Wednesday afternoon, just in case the bike showed up early. I came in Friday afternoon, and Radu arrived early this afternoon (Saturday).

----
CLASSIC ISLE OF MAN

Friday evening our rider, Allan, had a practice session for the Pre TT Classic road race on a course on the southern side of the Isle of Man. After picking up my luggage (delayed due to weather in Toronto), Lennon and I went to check it out.
Lennon and Allan, waiting in line for tech inspection...

Allan rides in a class of 500cc bikes built in 1972 or before.

Ever wonder how you get a race bike started?

Waiting to start practice.

Heading out for a few practice laps.

The paddocks... lots of eye candy.

----
BIKE COLLECTION

On Thursday and Friday, the word from our shipper was that the bike would arrive Saturday morning at 8:00am. My first thought was "oh boy... here we go again." I've had to deal with motorcycle shipping (and international shipping in general) enough to know that the first delay is often rarely the last. Lennon and I arrived at the designated drop-off point (a warehouse in Douglas, the capital city of the Isle of Man) at 8:30. No bike. So we started making phone calls. Our main shipping contact didn't have a reference number, and only knew the name of the shipper on the UK side of the ferry, not on the Isle of man side. So we got a list of the freight companies in town and called around. Long story short: after two hours of stressing out, running around town and thinking about what we were going to do if we couldn't get our bike until Tuesday (Monday is a bank holiday here), we got a call that the crates had arrived at our original meeting point. Phew!

So Lennon and I got to go unpack the crates,

load our mini-van with the little stuff,

and some of the bigger stuff (these are three of our four battery modules - more on the headache of shipping Lithium-ion batteries later).

And we waited for Allan to drive his van down to take the bike itself back to his house.

------
BIKE (RE)BUILD

When the organizers of the TT set us up with a rider, they specifically chose Allan because they knew he would help us out with all of the nigly little details that come up. He and his wife Jan have been a huge help so far in arranging accommodation, transport and Manx hospitality, but the biggest thing so far has really been the use of his garage. While many teams have paddock space at the grandstand where they can work on their bike, complete with semi truck, enclosed tent and electrical power, arranging that equipment from the US or renting it here would have been prohibitively expensive. Instead, we get to work on our bike in Allan's two-car garage with plenty of space and light, and (perhaps most importantly) away from any distractions like other racers or mechanics stopping by to chat and see our bike before it's ready. We have a lot of work to do, and Allan's garage has proven to be a great place to focus on it.

Lennon and Radu, just getting started.

Allan is working on his own bike as well. This is a Kawasaki he plans to ride in one of the gas bike races.

Before we could actually assemble the bike, there were a couple of tasks which required _further disassembly_. This is as far as we had to go in the "disassembled" direction.

We're concerned about the effect of water on the bike. We are on an island in the middle of the Irish Sea after all, and there is occasionally moisture in the air and on the ground. (If you've ever been to the UK, you know how tongue-in-cheek that statement is). Anyway, we decided to wrap our batteries in plastic and 'heat-shrink' it to make the plastic tight.

Always best to prototype before you use up tons of plastic.

Lennon shrinking one of the battery modules.

One of the wrapped modules. Think it will keep out the rain?

We had to cut holes in the plastic to make electrical connections, but then sealed up the holes with tape afterwards.

Radu, fitting a brand new, heavy-duty drive shaft that he made just before leaving Boston.

And, finally, we got to start putting the bike back together, rather than taking it apart...

Me, playing with tinker toys... I mean assembling rearsets for the bike (they're footpeg assemblies that allow a better racing position for the rider than standard fixtures).

Lifting the lower two battery modules into place.

We called it a day with three of four battery modules in place. The hope is to finish assembling the bike tomorrow (Sunday) morning in time for a test run on a local racetrack that afternoon. Can't wait!

-Mark

Landed

2011-05-28T02:59:00.004-04:00

It's happening! Lennon, Radu and I made it to the Isle of Man, and we're assembling the eSuperbike tonight. We have a lot of catching up to do in the story though, so I'm going to try to give some background through the next few posts while also updating on our current progress.

HISTORY...
I only arrived at MIT in January, so I'll start from there. At that point we had the frame of a BMW S1000RR, custom-designed battery pack from A123 Systems, two motors and almost all of the electric components to make them run, and an assembled-but-not-welded aluminum plate frame to hold everything together:

We also had a full CAD model of what our bike would look like
and a drive shaft custom-designed, analyzed and built by Radu (this is the finite element analysis of his design).
We could spin the motors with the motorcycle up on a stand, and even had our maiden crawl down the hallway outside our lab/workshop.
Maiden Crawl Video

But the plate frame wasn't welded, so we took the bike apart (note: taking the bike apart will be a recurring theme in this story).

and had it welded up.

With the bike back together, we ran it on the dyno...
Dyno Test Video

...and blew up a motor.

But more on that later. =-)

-Mark

eSuperbike

2011-01-24T17:40:00.004-05:00

For those who have been out of the loop - our apologies, we need a PR department on the team. As guys (and girls) who like to build things, blogging about it isn't that high on the priority list, as the urge for fabrication is quickly satisfied once things get built and then school takes priority over blogging . . . which is constantly on the back-burner.

We've been making advances on the eSuperbike since the summer - in one giant leap the aluminum subframe which holds the motors, controller and batteries is built and the major components are mounted - we are now down to the wiring detail, aerodynamic modifications and finishing touches (though this stuff always takes longer to complete than expected . . .).

Anyways, we have a photo of the initial bench-test setup:

as well as a video of the first motor spin-up at: http://www.youtube.com/watch?v=npeLbfHhAD0

Of course, we also have the details of the race, our team and progress all prettied up in our latest sponsor pack here: http://web.mit.edu/evt/MIT_eSuperBike_Isle_Of_Man.pdf

Stay tuned as we post progress updates and the first test-drives.

Burnout Mode Engaged

2010-08-23T10:07:00.015-04:00

After realizing that we had spare tires, all I could think about was doing donuts in the elEVen. Having never done a donut in the car, I decided to practice before hand. It looked more or less like this:

One difference is that I wore a helmet. As always, safety first.

In that same vein, we double checked all of the wiring and structural members to make sure that no short could occur, that all wheels would stay on the car, and that no oil would leak.

In our inspection, we found something wrong with the SCU. After 3 hours of debugging, we diagnosed the condition as dirty connectors between the motherboard and one of the cards. After cleaning the connectors, we fired up the SCU and sure enough the problem had been resolved.

We closed the SCU back up and soon we began the tedious process of remounting it back in the car.

The SCU was designed to fit into an electric school bus which has tons of space to mount components. Our Mercury Milan is a little more cramped making the mounting and unmounting process a more difficult. It is a three person job, with one person manning the hoist, another person making sure that nothing is in the way and the third under the car that aligns the SCU into its mounts.

Once every thing was back in, we went for a little drive up and down the street that our shop is on.

What follows are some pictures that we took before, during and after the first drive of this summer of the MIT EVT elEVen.

elEVen Status Update

2010-08-12T14:28:00.004-04:00

The heat is rising in MIT's Electric Vehicle Team shop. After late nights of soldering, countless breaks for Monster, and hours of tedious coding, our Mercury Milan conversion - the elEVen - is nearly street ready. The elEVen conversion and rapid recharging were delayed due to a problem with the motor controller, as was discussed in Stephen’s earlier blog post. While that problem was being resolved, the team wasted no time in starting other projects to increase the safety, comfort, and robustness of the car. These projects - including the battery cooling system, the mount for the charger, the charging adapter, the motor controller wiring box, and all of the internal communications - have either been finished or are nearing their respective ends to where the whole car can be assembled. Once the car is put together we can begin working on rapid recharging, but until then, the engineers in us are eager to get the elEVen running and on the road.

Here is our status on each of the elEVen projects:

A New Cell Cycler

2010-07-29T11:58:00.040-04:00

Recharge your electric car in less than 10 minutes! This has been the dream of many current and future electric vehicle owners. But imagine the batteries in your car could only handle this rapid recharging maybe 400 times - about the lifetime of a laptop battery, charging at a normal pace. Let's do some math: 100 miles (the range of the Porsche 914 BEV) x 400 cycles = 40,000 miles per car. Who would want a car with a battery pack that only lasted three years? [1] Not EVT! We wanted top of the line batteries that could handle our abusive rapid recharging and put up a fight for an acceptable number of cycles. Just in time, we came across A123, one of the industry's leaders in battery technology.

A hundred battery boxes later, we were ready to put our A123 cells to the rapid recharge challenge. In order to test our new batteries, Lennon Rodgers set up a station to rapidly cycle - charge and discharge - an A123 cylindrical 26650 battery, pictured here. After cycling the cell repeatedly, he hoped that even with the deteriorating effect of rapid charging on any type of batteries, the cell wouldn't lose much of its original capacity. His results are shown in the graph below.

Excitingly, after almost 1500 cycles, the cell barely degraded. So, 1500 cycles corresponds to 150,000 miles which is nearly the average lifetime of a car. [2] This is much more reasonable for a commercially marketable battery pack. Though this result is exciting for the possibility of rapid recharge technology, only one cell was tested which does not constitute a statistically significant sample size. Therefore I have spent the last few weeks setting up a new cell cycler. This cycler will rapidly cycle the same type of battery, a cylindrical 26650 battery and hopefully support the results from the first test.

Here are some technical details of the circuit. The cycler has two parts connected

to the battery through a set of relay switches: 1) a power source used for constant current charging at 10Amps and 2) a .25Ω resistor through which the battery can discharge. During the entire cycle, the battery temperature, voltage and current as well as the temperature of the resistor are monitored and constantly checked for dangerously high or low values. The data is sent through an Arduino-controlled circuit to a wireless ioBridge module which allows us to remotely upload data to monitor the status of the battery and keep a running chart of its capacity.

After a brief setback in which I killed a cell (thank you to Shane Colton for his assistance in soldering a new replacement cell), the cycler is up and running. In the time since it was turned on last Friday, July 30th, it has undergone over 300 cycles. It will take about a month to complete the goal of 1500 cycles, but the cycler is well underway and showing promising results. Stay tuned for the results on the second cycler test as a step on our way to rapid recharge technology.

[1] http://www.epa.gov/oms/consumer/f00013.htm

[2] http://www.arb.ca.gov/regact/grnhsgas/vmt.pdf

Manzanita Mounting Frame

2010-07-28T12:45:00.016-04:00

The project I have been working on for the past week or two has been fabricating a mounting frame for our charger. Though it may appear so from the outside, charging a battery pack like ours is not as simple as plugging it into the wall. The power first has to go through an intermediate stage before it can charge the batteries. For this intermediate, we have the Manzanita Micro PFC-50 (seen below). It is a charger that can handle anything from regular charging all the way up to very rapid recharging.Since the elEVen's current battery pack is in the trunk, it would be ideal if the charger could be in there with it. However, there was very little room left in the trunk with the massive battery pack and new cooling shroud, so I had to work within the remaining space. The only place the Manzanita would fit was above the cooling unit. Keeping the dimensions of the trunk in mind, I came up with a design in Solidworks. The whole frame would be welded together, and the Manzanita would be easily bolted on. Here is a preliminary design I made.
After double checking everything to make sure it would fit, I began cutting lengths from a bar of hollow, square cross section steel using our cold saw. I then drilled the mounting holes in them, and handed them over to Pete, our designated daytime welder, to weld together. While he was doing that I cut four small triangles out of steel plate and put a hole in each of them. The idea was to weld the small triangles to the bottom of the trunk, and then bolt the mounting frame onto them. This would allow easy removal of the whole frame while having a small permanent footprint in the car and allowing for the cooling shroud to be easily removed if necessary. Once Pete finished the welding, he hit it with a shiny black paint job, and it was done. It fits perfectly too, have a look.

Wiring Party

2010-07-23T13:35:00.010-04:00

These past few weeks I've been assigned to rewire the breakout box. Before it was a colossal mess but it did what it was supposed to, it got the car rolling.

This time I designed a much more compact wiring box that also incorporates the relay box and other small circuitry. It has one 0.5" cable that goes from the System Control Unit to the breakout box and it does everything else from there. It uses a d-subminiature as an input with two db-25 and two db-9 outputs. It is completely customizable to allow additional ouputs. It has a large 60 signal breakout board that centralizes all the signals that are going to the drivetrain. All of this is done in an enclosure about the size of just the original relay box.

Street Racing

2010-07-17T03:56:00.006-04:00

So I was driving down the road the other day in my all electric Mercury Milan when a Tesla Roadster pulled up next to me. Feeling a little confident about my car, I challenged the Roadster to a race. Within 4 seconds, I was already at 180 kph! I blew that sorry Tesla out of the water!

Here's proof:

That's right, I did it with no fuel. Or battery charge. And I left the parking brake on. And my car was telling me to pull over. It's because I was being too awesome.

What? You think I'm lying? Okay! Okay! You caught me.

The slightly more interesting story is that I have started to integrate the CompactRIO, which I mentioned in my last post, into the car. As a test to see if it was working, I decided to control the car's speedometer and satisfy my need for speed at the same time. The next step is to try to convince the car that everything is okay. I hope to get this done by the end of next week so that the car will be ready for inspection and license plates following soon after.

Things are really starting to come together and I hope that you check back regularly for new posts about our work on electric vehicles.

A Luxury Vehicle - The Little Things

2010-07-15T13:33:00.000-04:00

The little nuances are important when working with a luxury car (something you don’t think about until you are trying to maintain a luxury vehicle). The Porsche is a completed project that team has worked on in the past. Not only is it a beautiful car, it exhibits electric cars as a viable option. However, it is important that this luxury car look and run like a luxury vehicle. At the beginning of the summer, Pete one of the guys on the team noticed this creaking sound and decided it was creaking due to the suspension (the linkages, shock absorbers, and springs which connect the wheels to the vehicle). The decision was to look at the bushings on the suspension and make sure that they were well oiled.

This doesn’t seem like a big deal, but it can take up a lot of time. It requires moving the car and putting it on the lift. Then, we needed to start taking apart the suspension. This proved to be quite the task, in fact we ended up pulling out penetrating oil in order to disentangle rusted parts. We finally were able to pull the bushings out. We cleaned them thoroughly and spread oil on them. We than began putting all the suspension pieces back into the Porsche.

Good news – We got rid of that creaking sound, and I finally became a grease monkey (or at least I now consider myself in the club).

Thermal management of the battery pack

2010-07-15T13:14:00.000-04:00

One of the projects I'm working on this summer is the thermal management of our battery pack during rapid charging. Charging the battery pack in less then 11 minutes generates a lot of heat within the pack. To remove that heat and cool down the cells during rapid charging I've designed a cooling shroud to force air through the closely spaced battery cells inside the pack. To overcome the pressure drop inside the pack we're using three centrifugal blowers.

Breanna's Blog #1

2010-07-07T13:05:00.000-04:00

After much resistance, I have decided to finally begin my blogging for the summer. My blog posts might not seem quite as relevant as other team bloggers, but hopefully they will give a bit of insight into how our team works and functions as both a research group and student group.

Despite majoring in Course 2, before this summer began I lacked the hands on experience that is associated with such a degree – basic shop training. The first thing I want to post about is how I learned to use this equipment.

In the beginning of the summer, Steven Lam a fellow EVTer was designing and constructing an oil sump. In order to build specific sides of this oil sump he needed to use a milling machine. When Steven was working on it, he took me under his tutelage and taught me how to use the milling machine. By the end of this instruction, I knew how to change the mill bits for the various sizes and types of holes needed to cut into this aluminum and understood how the various planes of the mill worked and how they could be used to finish creating a design.

However, this lesson didn’t even begin to cover everything you need to know to use the milling machine. I needed to gain a lot more knowledge and experience before I could use the machine by myself, without being under some supervision. The options were reading a manual, helping my fellow EVTers machine stuff, and/or attending a machining class. Luckily, our team had a shop training class that weekend. After a 3 hour training on the mill machine, I felt comfortable to use a machine basically by myself (of course, I would still need to appeal to one of the senior members on my team to double check my set-up before I began to mill). In addition to this newfound skill, I also had joint ownership on “EVT bling” with Dianna.

SAE J1772

2010-07-07T13:04:00.006-04:00

Normally, when your car runs out of fuel, you pull into a gas station and fill up. Most cars run on regular, though some cars run on premium, diesel, etc. If you have an electric car, you probably have to drive home to charge up you vehicle, and likely use a custom made charging port for your car that you plug in to a normal wall outlet. Well, all of that is changing. Enter the SAE J1772 standard outlet.

This plug will be the new “regular unleaded” for EV’s. It is being used on the new Nissan Leaf, the Chevy Volt, and even Tesla is likely to take advantage of it. On top of that, charging stations are being built around the country by several companies, most of which will use the J1772. Having a uniform standard is important for large scale production, and is a necessary step if EV’s are to become mainstream.

This may sound great, but here’s the most exciting part: we’re getting our own J1772 port. I have been in contact with Tim Rose, the managing director of REMA EV, a company which makes electric power connections. They have been kind enough to donate the port along with the appropriate connectors, and if all goes well we’ll be getting one for the elEVen very soon and one for the Porsche in a few weeks. When it arrives I will be figuring out a way to install the port where the fuel filler cap used to go, and soon after we will hopefully have a way to charge the elEVen’s batteries.

Talking to Batteries

2010-07-01T12:03:00.005-04:00

EVT has worked a lot with the A123 26650 cells: we've cycled them, rapid-charged them, drilled into them, built packs out of them, all in a few semesters. At the beginning of this summer, we even charged the whole eMoto pack in 11 minutes and 30 seconds! This spring we got a shiny NEW toy: an A123 Prismatic Module.

The A123 prismatics have a much higher energy density than the 26650's and they come in a sweet pack arrangement. We have some single cells that we've been testing, and Lennon and Shane have built a rig to cycle one prismatic 1,500 times at a 6C charge/discharge rate. More updates on that later.
For the past few weeks I've been working on using an Arduino and an MCP2515 chip to talk to the BMS built into the Prismatic Pack. It talks over a CAN network, much like the systems in the Porsche or the elEVen. I've found that using the Arduino allowed me to start communicating in CAN easily in only a day or two, and now I can intelligently talk to the module, polling it for voltage and SOC information and telling it to actively balance itself. In the picture you can see the Arduino board sitting on top of the module, and the cable running over the top that connects the two together. The next step will be to output the battery data to a screen and create a system for talking to multiple packs, like we'll have on the next EVT motorcycle.

Say hello to the newest member of the EVT fleet, a blue Lifan motorcycle. This is the same frame that eMoto was originally converted from, and soon it will hold the above prismatic module and a shiny new motor. Last week Lennon, Randal, and I traveled down to Providence and bought the 2-year-old gas motorcycle from a guy who had never ridden it. When we returned, Randal and I ripped the combustion components and twelve volt system out (the lights and fairings had already been removed) and Will has begun designing a new frame to mount all the electric components. Look out for updates on the new frame and another new addition to our team.

-Manyu

Trip to Maryland

2010-06-28T15:26:00.002-04:00

This past weekend Adrian, Erick, and I took a trip to Maryland to pay Satcon a visit.

At the beginning of the summer we blew out a fuse and damaged a few components on our motor controller. We were powering it with a 12v charger instead of a regulated 12v power supply and had inadvertently given it 20 v.

We gave the guys at Satcon a call and they told us to bring it down. After an hour of probing they were able to narrow the problem down to the relay card. Apparently a diode blew and started shorting everything out. Satcon guys found another relay card in storage, robbed a few components, and then put everything back together for us. We crossed our fingers and turned it on. Luckily for us the laptop was finally able to communicate with the controller.

Let's hope it still works.

The Summer Team

2010-06-28T10:44:00.002-04:00

Now that summer projects are well underway, the team is on-site Monday through Friday, and often on the weekends. Check out the team profiles at http://web.mit.edu/evt/evteam.html to meet the engineers that are working hard to finish converting the elEVen this summer.

Work on the CAN network

2010-06-25T18:17:00.004-04:00

Hey Everyone,
My name is Erick, I'm a rising Senior in the Aero/Astro department and I'm pretty awesome. But enough about me, let's talk about what I've done.

I am working on the CAN network for the elEVen. In a few sentences, the CAN network is composed of nodes and communicates between nodes using 3 wires. Those wires are named CAN-High, CAN-Low and ground. When the voltage difference is zero, that is understood as a bit with a value of one and conversely, when the voltage difference is not zero, that is understood as a bit with value of zero. Do this thousands of times a second and you start to get a serious amount of traffic going through these three wires.

As a learning exercise, I am practicing with the Porsche 914 that we have already converted and am putting a few finishing touches on the interfaces. In order to tap in to this network, National Instruments has hooked us up with a CompactRIO with a CAN Module. I installed LabVIEW and have been messing around with it for a few days. After finally figuring out why I couldn't connect to the cRIO and the touch panel, here is the result of a few hours of work:

Once I become more familiar with LabVIEW, I will be able to receive, parse and send CAN messages. This will allows us to communicate vital messages, like the state of charge of the battery pack, vehicle speed, as well as slightly less vital messages, like what radio station you are listening to.

I'm excited to be working with the Electric Vehicle Team this summer and looking forward to all of the projects, which you will hear about through this blog, come to fruition.

Oh yeah, make sure to follow us on twitter!

elEVen- Summer 2010

2010-06-24T14:39:00.003-04:00

Hey everyone, EVT is back at it again this summer working on our 2010 Mercury Milan all-electric conversion.

Last summer the team was able to successfully remove the vehicle's original hybrid drive system and install a 250hp oil cooled 3 phase AC induction electric bus motor (courtesy of Satcon) along with a 20kWh A123 prototype battery pack consisting of 2,700 A123 26650 cells (many many thanks to A123). The elEVen first moved under its own power last August, but the conversion was far from complete.

This summer we have a new crew ready to pick up where last summer's crew left off on the elEVen. The two main goals for this summer are getting the battery pack ready for rapid recharging and making the elEVen street legal. To do this we will need to install an air cooling system for the battery pack, design a charging port capable of handling the huge power flux that rapid recharging will require and interface with the BMS (battery management system) motor controller and the car's own CAN networks through a Texas Instruments cRio programmable automation controller. There are also a whole bunch of other small projects that also need to get done so that the elEVen is the safe and reliable glimpse into what might be the future of automobiles.

Look for more blog posts about what everyone is doing soon.

Troubleshooting the elEVen Motor Controller

2010-06-21T17:32:00.007-04:00

About two weeks ago we tried to communicate with the elEVen motor controller but couldn't get a response forcing us to remove the motor controller from the car to figure out what was wrong.

We laid out the motor controller and all the components it interfaced with on a table in our workspace, first troubleshooting the electronics external to the motor controller. After not finding any problems in electronics outside the motor controller we suspected something was wrong inside.

We went through several troubleshooting procedures outlined in the motor controller manual but still couldn't get it to work. Fortunately for us, the engineers who designed the motor controller were helping us along the way. We thought we had narrowed down the problem to a electronics card inside in the controller that provided the controller with power. After inspecting the card and not finding anything wrong with it we've decided to drive to Maryland to get help from the engineers who designed the controller. Updates on our trip to Maryland coming soon.

A rapid charging electric motorcycle

2010-03-09T07:23:00.004-05:00

Over the last few months we've been working on a rapid charging electric motorcycle. Here's a picture of the full setup:

We made our own custom battery packs, charger, etc. It's using a battery-to-battery charging scheme.

We wrote up our full design, cell cycling results, etc. and have submitted it for journal publication. Hopefully we can release all of this information soon - very exciting!

Batteries in Transportation and upcoming events

2009-10-01T22:28:00.004-04:00

Today, MIT Energy Club hosted discussion series on Batteries in Transportation. It was very well attended by professionals in the industry, MIT students, from engineering and business school, Harvard Kennedy School of Government, Boston University, Northeastern University and Tufts . The main topics were the history of batteries, the advantages of Lithium-Ion batteries over other battery chemistries, and the limitations of the current generation of Li-Ion batteries, such as energy density and cost. Several potential solutions were proposed.

This discussion will be followed up by a related discussion on the stationary grid storage devices later this year.

We will have a busy weekend attending Lexington Energy Fair on Sunday and Altwheels 2009 on Monday. 56 vehicles of different sizes and applications, including MIT Porsche 914-EV,are expected at Altwheels.

2009 MIT Community Fall Break

2009-09-15T10:44:00.006-04:00

Yesterday, we attended the MIT Community Fall Break 2009. The event was designed to familiarize MIT community with GreeningMIT, an institute-wide initiative to encourage sustainable practices. It was a wonderful zero waste event with delicious food and compostable cups made from corn.

In early fall, we always try to engage MIT community in our outreach efforts. We had a superb turnout of incoming undergraduate and graduate students. If you are interested in joining the team, please see this page.

If you are looking to make immediate impact, check out the MIT Facilities Transportation page. It lists multiple options available to MIT students and employees. Students can take advantage of Zipcar heavily discounted membership and of subsidized T passes. Employees also qualify for Alternative Transit Subsidy and Bicycle Commuter Benefit Program.

Greenhouse Gas Emissions from One Gallon Challenge

2009-08-26T11:08:00.009-04:00

Just to complete the previous post, here a map of the United States describing the fuel mix used for electricity generation. Source: EPA eGrid page.

Emissions from tailpipe.

Gasoline and hybrid-electric cars emit through their tailpipes. They produce emissions and reduce air quality in the urban centers where population density is high. An electric car does not have a tailpipe. Here is a chart of CO₂ directly emitted by the cars during the One Gallon Challenge. [Based on DOE data, more info at Carbon Dioxide FAQ]

Emissions from well to wheels.

Even though an electric car does not have a tailpipe, an electric car produces greenhouse gas emissions where electricity is generated. These emissions are usually counted as "well to wheel" emissions, that is, a full life cycle of fossil fuels from their extraction to actual process of burning. They are differentiated from "tank to wheel" (or "plug to wheel" for electricity) emissions from the tailpipe.

Gasoline-powered cars, both conventional and hybrids, also produce upstream emissions. Most significant ones are emissions from the oil refineries that convert barrels of oil in gallons of gasoline. [Based on Argonne National Lab GREET]

A few comments:

Since we kept track of when we charged the car, we know that natural gas was used as a fuel to produce electricity for our drive. In general, you do not know which fuel was used to produce electricity for your air conditioner or flat screen TV. A common approach is to take US average grid fuel mix with 50% coal, which is almost twice as polluting as New England grid.
The 75 MPGe well-to-wheel number quoted in the AutoBlog was based on the US average grid. Had we taken New England numbers, we'd get above 100 MPGe. Had we charged our car with wind or solar power -- no fossil fuels used -- we would have infinite MPGe!!!

As you can see, an electric car is two and a half times cleaner than a gasoline-powered Prius with its strong 52.9 MPG. The main difference is the fuel. Our Porsche effectively used natural gas while Prius used gasoline. Had Prius used compressed natural gas (CNG), its greenhouse gas emissions would be probably about the same or even slightly lower than those from an electric car.

A conventional engine CNG vehicle, for example, the only mass-produced available in the states Honda Civic GX would not be able to rival an electric car because it lacks a hybrid option. There have been prototypes of CNG Hybrids, for example, Toyota Camry CNG Hybrid and Opel/(Saturn) Astra Caravan CNG Hybrid, demonstrated in the past year.

CNG Hybrids or Electric Cars?
As a society, should we focus on electric cars or CNG Hybrids?

Advantages of CNG Hybrids.

Price. Electric cars are quite expensive due to the cost of batteries. When our Porsche was built a few years ago, the battery cost for ~100 miles range was $36,000. If the car were mass produced today by a major automotive manufacturer, the battery cost would be closer to $15,000. It is still much more expensive than a hybrid powertrain.

Disadvantages of CNG Hybrids.

Leakage. Natural gas leaked from the refueling stations and from the car itself due to leaky hoses is a potent greenhouse gas, four times as damaging as CO₂. Because of that, developing a complex infrastructure for natural gas refueling may end up producing just as much harm to the climate as today's gasoline cars.
Renewable energy. Electric grid in the US will become greener with time. Emissions from the grid are already tightly controlled and budgeted (see RGGI, an initiative by ten Northeast and mid-Atlantic states). Addition of renewable sources, such as wind energy or solar power, to the fossil fuel powered grid will inevitably reduce well-to-wheel emissions from electric cars.
An average car in the US lives for about 15-17 years. An electric car sold TODAY emits as much greenhouse gases as TODAY's CNG Hybrid car. In ten years, an aging CNG Hybrid car will emit the same amount of CO₂ per mile or even more, due to leaky hoses. In ten years, the same electric car will emit less CO₂ per mile because its electricity will be cleaner. Electric cars are future-proof. That is one of the reasons our team is the Electric Vehicle team.

Gallons in an electric car?

2009-08-25T16:56:00.008-04:00

MPGe and gallons equivalent is a convenient metric to compare electric and conventional cars, but it's pretty evident that an electric vehicle does not burn gasoline. What does an electric car really use?

We monitored the charging behavior of the car closely and matched this information with the hourly data from ISO New England (wikipedia: about).
Here is a plot of electricity demand in New England with the profile of car charging overlayed. Both axes are in the units of power, MW stands for a megawatt (1 million Watts), and kW is 1000 Watts. An average incandescent light bulb is 60 Watts, an average compact fluorescent bulb is 20 Watts, and an average car has about 160 horsepower, equal to 120 kW. That makes 6,000 CFL bulbs in an average car.

The electricity demand follows a fairly typical summer profile. We use much more electricity in the afternoon (peak demand) than at night. The main use during the day is air conditioning.

The car charges whenever it is plugged in. Most electric cars will be charged at night in garages, on driveways, or on public charging spots. Just like we charged at our friendly hosts, Ford of Greenfield. We also charged during the day, in fact, during peak demand. Did it matter for the utility company? We'll see shortly.

United States fuel mix for electricity generation

United States electricity grid consumes about 50% of coal. Electricity produced with coal is particularly "dirty". Yet all states are quite different. Here is a fuel mix used in the New England: coal is only 11%, and renewables (including hydro) is greater than that. As you can see, the electricity demand on August 19th and August 20th were less than maximum capacity, so we did not run the dirty diesel generators.

The car charges "on top" of the demand bar, so we used capacity from a combined cycle natural gas plant. For this race, our Porsche was actually powered by the natural gas. It is a fossil fuel, yet its source is all domestic.

We were concerned whether our electric car mattered for the utility since it was being charged at peak. For the comparison, we looked at the difference between two consecutive days, Wednesday and Thursday. Wednesday was slightly hotter, so consumers used a bit more electricity. A difference between Wednesday peak and Thursday peak is 871 MW sufficient to recharge 414,762 electric cars like our Porsche

We will continue with the summary of CO₂ emissions from the race.

One Gallon Challenge: 164 MPGe

2009-08-25T13:01:00.017-04:00

Last week, the Porsche participated in the One Gallon Challenge, part of Boston Greenfest 2009. We traveled from Greenfield, MA to Boston City Plaza using 23 kWh of battery power, equivalent energy to 0.65 gallons of regular ethanol-containing gasoline. That translated to 164 miles per gallon equivalent (MPGe). Here is a link to our path. We also got lost on the way which added a detour, so the total length of the trip was 118 miles.

View Larger Map

Both in Greenfield and in Boston, we had a tent for the car and a lot of visitors. Outreach and public education is an important part of our effort. For everyone who stopped by to see our car last week, thank you.

A day before the race, we drove from Cambridge, MA to Greenfield, MA. We completed this drive on a single charge during the prior night. In Greenfield, MA we charged using 240V AC at Ford of Greenfield which generously let us park there at night.

However, we were not able to fully charge during night due to logistical difficulties, so we started the race with 80% full batteries. We had to recharge on the way. Luckily, Colonial Dodge of Hudson, MA let us park next to their service bays during the day and fill up our battery.

Charging at Colonial Dodge

We also had two cars, a hybrid-electric Toyota Prius and conventional Pontiac Grand Prix which drove with the Porsche. We took the chance to compare the vehicles against each other considering all three cars drove together along the same route.

Toyota Prius ran the race at very respectable 52.9 mpg, while the Pontiac Grand Prix did 22.8 mpg, fairly typical for a midsize sedan. We observed that fuel economy measured in mpg is not as telling as fuel consumption, usually measured in gallons per 100 miles or in liters per 100 kilometers, a European metric. You can readily see a difference between equivalent fuel consumption of an electric, a hybrid and a conventional car on this plot.

More updates are coming about our recharging experience and about our greenhouse gas footprint.

Update: There was quite a bit of press coverage for this event.
One Gallon Challenge: alt-fuel "race" cars get up to 164 MPGe

The feasibility of rapidly charging EV's

2009-08-21T09:38:00.008-04:00

Below is a poster I put together describing the feasibility of rapidly charging EVs.

There are three main things to consider: (1) Cell chemistry (2) Power source (3) Chargers and (4) Battery pack design.

The good news is that it's all totally feasible - though research & development is obviously required! A123 has already developed the cells necessary.

Remember that drivers would not rapid recharge all of the time. Most of the time they would charge EVs for the lowest cost - slowly - over night in their garage. But in the event they need the extra range, rapid charging should be an option.

Included is a chart Shane and I (with help from professional electrical engineer Dave Rodgers) put together. It shows how you could rapid recharge a motorcycle at home, while a sedan would require higher power - which is already available in most industrial buildings (think Home Depot, Best Buy, etc.).

Thus our vision is that the rapid recharge stations would not be at home - but rather at fueling stations like Hope Depot, Shell Gas Stations, etc. This is totally feasible - and the power already exists in many of these buildings.

(click to enlarge)

Electric motorcycle update

2009-08-21T09:10:00.008-04:00

A couple years ago I built this all-new electric motorcycle - for $3,000 - using parts available on the internet: www.electricmotion.org.
Here she is parked outside the Caltech student machine shop - it's place of birth:

Now I'm back at MIT - and found some like minded enginerds that are interested in some e-motorcycle research.

Paul, Mike, Shane and I have been working on a rapid recharge pack for the above motorcycle (aka eMoto). We're designing/building a charger that will charge the pack in 10 minutes. The same design can be scaled up for any pack size - including a car.

Here are some pics of our very recent work:

Charger thoughts:

Battery welding (thanks to our sponsor Miyachi):

We're very constrained with space, etc. Here's a finished module (BMS boards sitting nearby - provided kindly by Texas Instruments - thank you!!):

One of the lithium modules on the motorcycle - datalogger on tank:

One module (as shown) - lead vs. lithium - you should feel the difference!
Lead acid: 333 Watt-hrs / 44 lbs of battery (actual)
A123 Lithium: 380 Watt-hrs / 10 lbs of battery (predicted - includes weight of enclosure, etc.)

Working on the charger (gray box w/ lid removed):

We're also using a commercial charger (which can't charge quite as quickly - roughly 20 mins) - with help from Manzanita Micro - (thanks Rich!).

Quick Fabrication Update

2009-08-20T10:00:00.011-04:00

We've got the new high voltage wiring routed in the car, the battery mounting enclosure is almost completed and Mike is tweaking the chain drive unit. There's no design work left at this point: the path to the finish line is clear, with a rush to finish the final assembly.

Sprockets and chain guard are in place, with Mike grinding a small channel to make room for the motor encoder wire.

Kevin, finishing the enclosure for the trunk-mounted battery pack.

The orange high-voltage (356 Volts) shielded battery cable runs from the rear to the front of the car, from the battery pack to the motor controller.

Arya has been working on getting the hood latch assembly back in place - it had to get cut off to make room for the motor controller enclosure (the clear plastic box to the right of the engine bay with the orange cables running into it).

Porsche: 90.28 Miles

2009-08-15T21:31:00.006-04:00

The Porsche has set its first calibrated range record: 90.28 miles!

The Porsche crew has been hard at work over the last month preparing to climb Mt. Washington and compete in the 1 Gallon Challenge.

Tyler, Mike, and I decided that Thursday was not the best day to do the hill climb, many of the concerns regarding braking and regen performance had not been adequately answered, and with only 3 people going, it didn't make sense to spend so much time driving there and back.

With a trailer and tow vehicle already secured, we decided to seize the opportunity to take the Porsche out on the 1 Gallon Challenge route and see how far we could safely go. We followed the route backwards starting from Cambridge and driving out there. We got stuck in traffic and took a long detour on the wrong Beacon St., stopped in a gas station to dodge a summer sprinkle (without a rain cloud in sight), the trailer got rear-ended and we spent a few hours eating ice cream while the police sorted out the paperwork. It was getting dark and cold, so we trailered the Porsche back to city lights and finished driving around town.

Heating only becomes an issue when driving in 3rd (i.e. high torque, low revs). We have motor temperature logs & need to analyze exactly the parameters when the motor overheats. It drives very well in 2nd, which is perfect for the country roads that are along the route. At the end of the drive, some capacity mismatch seemed to exist between the cell groups in the pack, but they all charged up perfectly balanced (so there isn't too much cell efficiency mismatch). Since this is the first time the pack has actually been balanced and fully cycled, we're hoping that some of the mismatch will work itself out as we cycle the pack more.

A lot of work has been going on in preparation for these drives, I'll detail more of what we've done in a coming post.

Porsche Center Console Construction

2009-08-08T02:33:00.009-04:00

Not to be outdone by the factory-built touchscreen console in the Milan, the Porsche crew built and installed a new center console for its touchscreen connected to the NI cRIO. The console was built by EVT's newest member, Amanda Turk, and team advisor Dan Lauber over a very productive weekend filled with tools and materials uncommon to the EVT.

We built the center console completely out of wood and woodworking bits, except for a few custom sheetmetal brackets. These are the same materials which the stock Porsche center console, on which our design was based, was made from. The center console is a highly visible and functional fixture in the car, so there was a laundry list of requirements in designing and building it. It had to look stock, not interfere with the operation of the accelerator, shifter, or adjustable seats, fit the National Instruments touch screen and cRIO controller, be sturdy enough for abuse, provide room inside for wiring and outside for the eventual addition of switches and indicators, and provide easy tool-less access to all the wiring and electronics inside it.

We mocked up the entire console in cardboard before making a run to Home Depot for lumber. The cRIO was mounted against the front wall, above the passenger's toes, we added a floor board under the passenger's feet to protect the wiring (it was originally just a big chunk of foam), and we re-routed a good number of the wires and cables.

One of the more interesting bits of construction, the touch panel was meant to mount to a much thinner panel, requiring the routing of the back side of the plywood panel with a 1/4" end mill. A couple layers of paint, and the center console was ready to show off at the open house and looks fantastic. Still to do is organizing all the wiring inside, and thanks to Amanda's mad sewing skills, a genuine viynl cover instead of paint. Also part of driver information/fit'n'finish is getting all the gauges working and looking stock.

Fabrication Progress

2009-08-07T20:02:00.009-04:00

The motor/differential/speed reducer assembly and the motor controller (the two largest components in the engine bay) are mounted in their final locations. It barely fits - had the controller been 1 inch larger on any side and it wouldn't have fit in the engine bay unless the motor and transaxle were a parallel unit (motor laying flat, transversely in the car), with the controller laying flat on top of it. An advantage of the current configuration is that the motor, controller, gear drive and differential are all visible from the top, useful for outreach/demonstration.

Motor/speed reducer/differential assembly Version 2.0 is hanging from the lift; on the right you can see the motor controller (the black box) mounted in a polycarbonate enclosure (we went a little overkill on the waterproofing).

This photo is taken from inside of the engine compartment; you can see the clearance between the motor controller box and the top of the hood (the underside of the sheet metal) is about half of an inch.

The new motor frame, as seen above, clamped to the welding table - this is necessary to prevent the welding heat form warping the frame. This is version 2.0, which is slimmer and allows for the clearance to mount the motor controller next to it in parallel.

The components for the chain-drive speed reducer. From the left: flexplate adapter (connects the lower chain sprocket shaft to the differential); spline shaft and sprocket spacers (connects to the motor at the top); lower chain sprocket shaft with the lower bearing mounted and the other side of the triangular flex plate adapter.

Nonstop Fabrication

2009-08-01T12:21:00.028-04:00

We've been working around the clock (well, almost - a typical day starts at 10am and goes until 2am, including weekends) to get the fabrication done. We finally have the components we need and our CAD models are worked out, with the final assembly and mounting left. The pictures below may explain the lack of blog posts in the past few days.

The choice between spending more time in front of a computer vs. spending time in the shop with a TIG welder usually favors the latter: we can't wait to get this car on the road.

Mike, welding the coolant pump mount to the frame rail.

Matt, machining the 1/2 inch thick aluminum walls for the chain drive enclosure. The bearing plates for this cannot be allowed to flex at all, otherwise the chains (we're using 4 in parallel) will become unevenly loaded, leading to a cascading failure after the first chain snaps.

Arya, about to mount the wiring harness/interconnect box.

The motor / diff frame assembled and mounted in the car. A 1.7:1 ratio chain drive connects the two. This is our first iteration of this frame; currently we're working on the second one, that will be slimmer at the bottom and slightly offset to the left, to make room for the motor controller box.

A (very rough) mounting of the motor controller box. This will house the 640A, 400V controller electronics, and needs to be watertight. It's constructed from 1/4" polycarbonate, with a 3/8" sheet on the mounting surface of the controller. 1/2" thick polycarb is bulletproof.. It's waterjetted and dovetailed at the ends, which will be bonded and sealed with silicone.

Jigging up the motor/controller frame, version 2.0. This time we'll get it right . . . no warped joints, no flex, slimmer by 4.5" at the bottom, leaving more room in the engine bay for mounting other components and (future) battery modules.

The sponsor logos on the car, prepped for the open house (the shop was much cleaner for that event). We had the president, provost, supporting faculty and corporate sponsors stop by and attendance remained strong throughout the evening.

The custom 17-spline shaft for the motor is finally here. It was much cheaper to send the shaft out to be made via EDM (electrical discharge machining) rather than a conventional broaching method.

. . . more to come in the next few days

News Update

2009-07-22T16:07:00.004-04:00

Nick Barber from IDG News Service stopped by last week; below is the video.

The article is here: http://www.pcworld.com/article/168834/mit_electric_car_may_rival_gas_models_on_performance.html

Week 5 Update

2009-07-17T14:48:00.001-04:00

Saturday July 11th:
Car Dismantling:

Today, we started dismantling the car at 9am. We finished removing the engine at 3am and were out of the shop at 3:30am. We completed all of the major dismantling in only one day. We took out the gas tank, the battery pack, the engine, and parts of the interior. Take a look at our blog to see a time lapse of the whole day! It is an awesome video!
http://mit-evt.blogspot.com/

Sunday July 12th: Final dismantling:
In the morning, I finished removing the rest of the things from the engine compartment and I rebolted the suspension in place so the car can roll. The car is pretty much entirely ready to have new parts installed in it.
Drive Train Revision:
Radu and I had a long talk in the morning about the drive train. The original plan was to put the motor in the exhaust channel under the car and then run a shaft up to the differential. This plan had a couple of serious drawbacks: first, we would have to invert the rear differential which could lead to lubrication problems; second, we would have to cut into the exhaust channel and do body work which is in general a pretty bad idea; third, we would be spinning the differential at 12,000 rpm when the car is going 100mph. After thinking about all these challenges, I thought up another way that we could do the drive train which will probably be a lot easier. My idea is to mount the motor above the differential and have a chain drive linking the two. The chain drive will give us a lot of flexibility with the gearing and the whole assembly will just sit where the old engine was. This plan solves all of the major drawbacks of the old plan but introduces a few new challenges. Mainly, the chain drive and all the mounting. Radu and I both really like the idea and we talked to the rest of the team about it and they also think it is a good idea. I made a CAD model of the whole motor/differential assembly in the evening and I plan to talk it over with the other guys tomorrow.
Monday July 13th:
Mike, Radu, Matt, and I had a long design powwow in the morning about the motor/differential mount. We decided that the best way to do the drive train is to rigidly mount the differential to the motor and then mount both of those to the car through the existing motor mounts and several anti-roll bars. Here is a picture of the CAD model that we finally settled on.
Tuesday July 14th: Motor Frame:
Today I assembled all the basic components of the frame and tack-welded them together. Cutting the compound angles on the cold-cut saw was a little bit of a challenge but Mike had a good suggestion to make angle blocks and it worked very well.
Differential:
I spent several hours calling junk-yards and BMW shops in the area to find a differential that we can use. The Ford 9 inch differential that we have and were planning to use before is too big to fit in the car so we decided to look for another, smaller differential. Because our motor will be outputting so much power, we want a very strong differential so we decided on a BMW rear differential. We would like to get a Limited Slip Differential to improve our handling but it is not critical. I ended up finding a good used transmission at Nissenbaum’s auto salvage very close to the shop. I went over there and picked it up in the afternoon. The guys at Nissenbaum’s were very helpful and were very interested in our project.

Wednesday July 15th: Motor Frame:
Mike and I went in the morning and water-jet cut the front face of the motor mount. It took about 25 minutes worth of cutting time because the steel was 1/2” thick. I welded the entire frame together and fitted the motor and differential into it. The frame itself weighs about 50-60 lbs. With the motor and differential, the frame weighs about 400 pounds.

Thursday July 16th: Differential:
I degreased and repainted the Differential so it is protected and looks good. I sized, lined up, and drilled the hole to mount the differential to the front plate of the motor frame as well as the hole where the shaft goes through the front plate of the frame.
Motor & Differential Frame:
I finished welding the pieces that Matt made for the engine mount cross bar. The steel frame is mostly done. All that is left is to make the cover for the sprockets. Here are a few pictures of the frame. The differential is the black thing on the bottom and the motor is the aluminum cylinder on top. The third picture shows the frame placed in the car. This is how it will look when everything is mounted correctly. The box on the end of the motor is the oil sump. It holds the extra cooling oil from the motor and fits very nicely in the old exhaust channel.

2009-07-17T14:46:00.001-04:00

Wednesday July 8^th:

Motorcycle Battery Pack:

I spent most of the day revising and finalizing the motorcycle battery module design. Lennon, Mike, and I talked a lot about the design. We could not decide between on how to cool the pack. The two designs that we were playing with were to have barb fittings on each module and have a central air blower to send air through the modules or to have fans on each module. The advantage of having individual fans on each module is the simplicity but the modules would not be water tight. The advantage of the central blower idea is that it is more scalable to the car battery pack in the long term and it allows us to seal the individual modules better.

Thursday July 9^th:

Motorcycle Battery Pack:

I made a cardboard mockup of the battery module. Mike and I decided that we are going to use a central blower to push air through the modules.

Friday July 10^th:

Motorcycle Battery Boxes:

In the morning, Mike bought more polycarbonate plastic and water jet cut the enclosure for one of the motorcycle battery packs. The modules will be cooled by blowing air through them. Each module has two barb hose fitting, one to blow air in and one to let air out the other side. Here is a picture of the final battery enclosure. The tape along the seams is to make the enclosure water tight. Now that the enclosure is complete, all we have to do is wait for the battery welder to get here and then we will be able to assemble one of the packs and try to fast-charge it.

Mercury Milan Test-Drive:

In the afternoon, the whole team drove over to the Costco parking lot to test drive the Milan. The car was really fun to drive! It drives like a normal car but if you pay close attention, you can notice when the electrical systems kick in. The GPS system and the digital dash are really neat too and they work well.

elEVen: Work Day 1

2009-07-12T04:07:00.009-04:00

Engine, transmission, exhaust, fuel tank, hybrid battery, center console, 2 front seats removed.

15 hours, 16 cans of Monster.

Team Update

2009-07-10T12:30:00.007-04:00

The team has been preparing for this moment: a 2010 Mercury Milan Hybrid is sitting on our lift, about to be assaulted by all of the tools in our shop. Within three days the most patented car in automotive history will have its hybrid drive system sitting on the floor of our shop in a corner, to be replaced by our 250 horsepower electric bus motor and lithium-iron phosphate battery pack.

With these delays, we have exactly four weeks to finish the mechanical conversion of the car. The new motor cooling system is set up, the 650A controller is tested, the limited slip differential with 7.33:1 gears is ready, the A123 battery pack communications have been resolved and the raw material stock has been ordered. As students, all we have is man-hours to throw at the problem; given the timeline, we’re grateful to our friends at Monster. The details of this intense grind will, of course, be posted for your viewing pleasure.

Driving the elEVen base vehicle to Cambridge

2009-07-10T11:30:00.027-04:00

Dan and I picked-up the team's Mercury Milan Hybrid at Ford Motor Company in Dearborn yesterday morning and drove it back to Cambridge. (But not before first enjoying a nice sunny sky in Michigan. It has been unusually cloudy and raining in Boston ever since early June.)We left Dearborn around 5:00 pm yesterday evening and arrived at the EVT shop at around 9:00am this morning. We opted for the longer route, passing through Toledo, Cleveland, Buffalo, Syracuse, Albany, and Springfield instead of through Canada. Plus we got to see all sorts of cool and interesting rest stops along the way!* (See example parking lots on the right.)

Driving for 16 hours straight (our only long stop was for dinner), wasn't nearly as painful as I think either of us expected. Due in part to the vehicle we got to test drive the entire way. Ford's improved hybrid system uses a e-CVT and larger, more powerful electric motors. The Milan Hybrid gets an EPA fuel economy rating of 41 mpg in the city and 36 mpg on the highway and can run in EV-mode up to 47 mph. More information:
http://www.mercuryvehicles.com/milan/

Not only is the Milan Hybrid an efficient hybrid system, it has the new Synch system, a great navigation system, and (most importantly for nerd engineers like us), an interactive and highly configurable instrument panel geared toward increasing fuel economy. You can even configure the vehicle to display fuel consumption (in L/100km) instead of fuel economy (in mpg). For information about why this is so useful see: http://www.mpgillusion.com/

Here's an image of the instrument panel from http://articles-ford.blogspot.com:

And here I am filling our car up, for possibly the last time, in Springfield, MA:

* Indicates sarcasm

Bryan and Scott's Porsche Work

2009-07-09T15:11:00.007-04:00

Over the past few days Bryan and I have been working on the wiring project for the Porsche. The wiring under the car and in the mid-car section was a complete mess, and we worked on cleaning it up to make it look better and make it easier to work with in the future.

Bryan holding a bundle of wires from the middle of the car

To start out, we wired up a terminal box in the front and back of the car that we'll be using to rewire the mess underneath and inside the car.

After we finished wiring up the terminal boxes, we started redoing the wiring inside and under the car. First we pulled out the DC/DC converter and decided to mount it underneath the terminal box in the back of the car. I designed and built a mount for it using sheet metal. I also made room on the mount to attach a relay so that when the car is plugged into an AC outlet, the DC loop is disconnected. The mounting device was also designed so that one cannot easily stick their fingers in any electrical components and get electrocuted.

This is a picture of the wiring on the DC/DC converter.

While I was working on this, Bryan and Dan first had to analyze where each of the wires in the bundle from the DMOC were actually going. After this was documented, they removed the unnecessary bundle and started rewiring.

They are currently working on wiring everything through the terminal box, including regenerative braking and accelerator wires. This will not only make everything look a lot cleaner and more streamlined, but make access easier for future work.

More pictures to come soon!

2009-07-09T12:54:00.012-04:00

Over the past few weeks I have been in the process of designing the drive train for the elEVen vehicle. During the process I explored several different options including using a transaxle or a speed reducer in conjunction with a differential. I eventually settled on a direct drive system using a Ford 9” differential with 7.3:1 gears. This reduction ratio was chosen to give the car a top speed of 100 mph while minimizing the 0-60 time. By using a direct drive system we will be able to minimize the complexity and weight of the drive train.

The Ford 9” was chosen due to it’s the large aftermarket community and wide range of reduction ratios. Because the Ford 9” is a solid rear axle differential several modifications will have to be made to install it in the front independent suspension. These include mounting the differential upside down and using a independent rear suspension carrier.

Since deciding on the Ford 9” we went ahead and ordered a rebuilt 9” Trac-Loc limited-slip differential assembly with 7.3:1 gears. We also ordered an independent rear suspension carrier made by Dutchman Motorsports. Since the IRS carrier came with Porsche 930 CV stub axles we went ahead and ordered matching CV joints for our half shafts. Below you can see the assembly, carrier and stub axles assembled.

As I mentioned before, the elEVen is going to have direct-drive system with no gearing between the motor and differential. The coupling will be done using a u-joint and a rubber flex-plate. The u-joint will allow us more freedom when mounting the motor, while the flex-plate will dampen out oscillations caused by any misalignments in the drive train.

The u-joint will be assembled out of a u-joint style slip yoke that will slide over our motor spline shaft and a custom adapter yoke, which I will be machining next week. The adapter yoke will have a 1310 size u-joint yoke on one side and a flat flange that connects to the flex-plate on opposite side. On the other side of the flex-plate will be another custom coupler with two flanges, one to connect to the flex-plate and one to bolt to the differential pinion. This coupler will also have to be machined by hand next week. Today we placed the order for the 4140 steel round stock for the pars so hopefully I will be able to get into the machine shop Tuesday or Wednesday to start making them. So far I have made some rought solid models of both couplers, which I will be refining as I discuss my plans with shop guys. Below on the left you can see the model of the adapter yoke and on the right the differential coupler.

Here are both parts attached to a model of the flex-plate.

2009-07-08T09:31:00.006-04:00

Monday July 6, 2009:
Charger:
In the afternoon, I also looked into what charger we want to get for the elEVen car. Chargers cost between 2000 and 5000 dollars for a high powered good one so this will be a pretty significant purchase for the team. There are about a half dozen companies that make electric vehicle chargers. Right now, we are looking at getting a Manzinita micro charger. They are very robust and versatile and give the user a lot of flexibility.
In the evening, we had our weekly meeting and then Dan presented the results of his modeling work. According to the drive cycle and the modeling code he used, the Mercury Milan will have a 0-60 time of about 8 seconds and will average about 460 watts/mile. This mileage estimate seemed high to us so we are going to look into it more and make sure all the parameters in the model are correct.

Tuesday July 8, 2009:
Motorcycle Battery Pack:

Today I worked on the CAD model for the motorcycle battery pack. I am going to try to push to have another prototype of the enclosure done by the end of this week. I finished most of the CADing and just have to put on the finishing touches. Here are a few pictures. The black strips are rubber tap for vibration isolation, there are two barbed hose fittings to attach cooling air hoses to.

2009-07-03T09:55:00.003-04:00

Wednesday July 1, 2009:
Battery Testing:
I finished testing another 1500 cells or so. That brings our total number of good cells to 2700. At this rate, it will take another 4 days or so to finish testing all of the batteries.

Motorcycle Pack Design:
Mike and I worked on the design of the motorcycle pack some more today. We plan to seal the four modules to keep water and other harmful elements out. In order to cool and vent the cells, we plan to have two barb fittings, one on each side of the enclosure that we will attach hoses to. These hoses will in turn be attached to a central manifold assembly with a high powered blower that will pull air through the pack. We think that by centralizing the point where air is exchanged with the outside, we can better control the airflow and prevent condensation or excess water or particles from passing through the pack and causing a short. We are going to revise our CAD model in the next couple of days and post a picture of the new design when we finish it.

2009-06-30T22:35:00.007-04:00

Tuesday 4-30-09: Battery Testing:
The long tedious testing of the individual batteries has begun. After talking to our contacts at A123 and other EV teams, we decided that the two most important indicators of a battery's health are voltage and impedance. We plan to first measure the voltage of all the cells that A123 donated to the team and throw out any cell that are not between 3.296 and 3.340 volts. The cells have been sitting for 3 years so if the voltage is within this range, it is a good indicator that the cell is sealed well and that there is very little current leakage through the cell. This range was given to us in the A123 battery pack design manual that is available to the public. This design manual has a lot of very useful information about building a pack and particularly about building a pack with lithium iron phosphate batteries. Today I checked over a 1000 cells. My goal is to get all the cells checked before the car arrives next week. Today, Mike and I also went to the electrical engineering lab and used their impedance tester to check a box full of good cells (cells that passed the voltage test). The average impedance of the cells was 7 milliohms with a very small standard deviation. It seems to me, and the other team members agree, that we only need to measure the voltage of the cells in order to tell if they are good or not. In other words, if a cell passes the voltage test, it should pass the impedance test as well. If we decide that this is a reasonable assumption to make, we will be able to save a lot of time by just testing the voltages of all the cells.

Cell Level Battery Pack Fuses:
Today I ran a couple of tests to determine if the individual cell fuses are sized correctly. Our nickel sheet is .010" thick and the tab fuses are 5.5mm wide. A123 sizes their fuses to be 3.6 mm wide and .007" thick nickel sheet. They rate there fuses to blow at 2100amps in .1 seconds. Our fuses are currently about twice the cross sectional area of A123's. We wanted to investigate this further so we ran a few tests using an A123 26650 cell. We estimated that an A123 cell can output 300 amps in a short. We cut two test strips of nickel. One that was the size of the fuses that we are currently using on the motorcycle packs and one that was the size of the A123 fuses. Both blew when we shorted the battery across them. This was a good sign because the purpose of the fuses is to protect against a short. After talking it over, we decided to stick with the 5.5mm width rather than reducing it to 3.6mm because we do not want to risk the nickel heating up when we rapid recharge these packs. I went ahead and ordered enough nickel to finish the motorcycle packs and also build one of the car modules. We bought our nickel from National Electronic Alloys Inc. They have a very good selection and they also have good prices.

BMS Updates

2009-06-29T13:58:00.005-04:00

After several meetings over the past week, we have decided to use a LTC6802 BMS IC as the main BMS circuitry for the slave boards. We will interface them to a main controller via an optically coupled interface. The main controller will be designed around an MSP430. The data sheet for the LTC6802 can be found here:

http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1037,C1134,P86662

More info to come soon...

-Eric

The Battery Pack

2009-06-29T11:23:00.012-04:00

The past week or so has been spent designing a prototype battery pack for Lennon's electric motorcycle, eMoto (http://www.electricmotion.org). We'll be replacing his 240 pounds of old-school lead acid batteries with a 30 pound pack of A123 LiFe cells. Of course, this pack will only have about 75% the capacity of the lead acid stack, but the power and weight improvements will be significant.

This pack isn't a favor for Lennon though. It'll serve as a test platform for future pack design for the elEVen, as well as demonstrate rapid-recharge capabilities on a smaller scale. Consequently, the pack has a very similar architecture to that of the proposed elEVen pack. We've run into a lot of problems during the design process which we never anticipated. It's very likely we'll run into the same problems on the full sized elEVen pack, so hopefully we'll be able to get a lot of bugs out with this small scale version.

Here's an overview of the basic design, both for the elEVen and the eMoto:

Modularity: It is rather difficult to make an electric vehicle without using high voltage, which can be very dangerous to work with if proper precautions are not taken (just like gasoline in ICE cars. It's just a property of high energy systems). The obvious solution for dealing with the dangers of high voltage is to eliminate the high voltage itself. We are accomplishing this by building several independent low voltage modules, which will be wired in series to create the high voltage required only at the very end.
The eMoto pack will consist of two 19.8 volt (6 cells in series) modules and two 16.5 volt (5 cells in series) modules wired in series to reach the nominal voltage of roughly 72 volts (required for the motor controller). Each module will have 10 cells in parallel to achieve a capacity of 1.6 kWh for the entire pack. We originally intended to use three 24 volt modules, since the elEVen will be using 24 volt modules, however, we decided to use the existing battery mounting on the eMoto. This made arranging seven of the ten cell batteries in series very difficult. Thus, we arrived at the much simpler pack design we currently have.
We anticipate that the elEVen pack will consist of 24 volt modules with 72 cells in series. However, the issues we ran into with the geometric constraints of the motorcycle could arise when designing around the existing chassis of the elEVen. Hopefully the experience with the eMoto will help us keep our future designs a little more flexible. Additionally, the eMoto will have the four modules wired directly to each other. We plan to connect the elEVen modules with contactors, allowing the packs to disconnect and drop the maximum voltage to 24 volts. This will provide a safer working environment as well as making the vehicle safer if it is ever involved in an accident. Finally, each module will have a built in Battery Management System (BMS), which will then communicate to a master module to balance all of the modules together.

Inter-cell Connections:The individual cells of the modules have to be connected some how. We took a lot of advise from the likes of Bob Simpson (http://www.evdrive.com) and Bill Dube (http://www.killacycle.com/) and have decided to use nickel plates spot welded to all of the cell terminals as the interconnects. These nickel plates will be bent to help arrange the cells in each module. They also have tabs for individual cells with integrated fuses to protect the pack should a cell internally short.

Cooling:As we rapidly recharge the cells and continuously discharge them, they will heat up. Though warm cells have a lower internal impedance and are therefore more efficient, running the cells too hot will damage the internal structure and reduce the life of the pack. We'll be air-cooling the cells across the electrical contacts, since they are both electrically and thermally coupled to the inside of the cell. We don't anticipate that a lot of cooling will be required (see the section on battery data which will be posted soon), but we want our design to be flexible in case more cooling is required. We accomplished this by spacing the cells vertically to allow airflow. However, we have not finalized the method of spacing (the leading idea can be seen below). We're also looking into various methods of cooling, including passive cooling and using various arrangements of computer cooling fans for active cooling. We'll be testing the effects of various cooling systems once we finish the prototype eMoto pack.

Cell enclosure: This has surprisingly been one of the more difficult aspects of the pack design. The cells need to be restrained somehow, and in the case of the eMoto, the enclosure also needs to be able to take a compressive load. We were originally looking at using FR4 as the primary cell enclosure for its insulating and fire retardant properties, and an aluminum secondary enclosure to provide rigidity. Since then, we've looked at a single FR4 enclosure design, an FR4 primary and polycarbonate secondary, polycarbonate primary and secondary, and a single polycarbonate enclosure. Currently, we've decided on a 1/8” polycarbonate primary which will likely be encased in a polycarbonate secondary with possible rubber shock-mounts in between the two layers. The shock-mounting will reduce the effects of vibration on the cells, hopefully preventing any of the connecting welds from breaking.
After figuring out the enclosure materials, we had to design a good way of creating a box. This sounds trivial, but there is a lot more that goes into it than meets the eye. In our case, we were limited to making the box out of sheets of polycarbonate. This was the only cost effective way of obtaining all of the necessary features, such as cooling slots and cell dividers. Machining a solid piece of polycarbonate into the shape we wanted would take too much time, cost too much money, and waste too much material. Therefore, we had to come up with a good way of joining the polycarbonate sheets together into a box. We looked into drilling and tapping screw holes into the thin face of the polycarbonate, but in order to do so, we would need to use #0-80 machine screws. That method of fastening seemed impractical and labor intensive while possibly being insufficiently strong. We also looked into chemically bonding the polycarbonate together. We've decided to do so on the prototype eMoto pack, with the addition of interlocking tabs for added mechanical reinforcement. We are considering using polycarbonate angle stock to reinforce the corners. As of now, the box seems pretty rigid.

As of now, we've assembled the primary enclosure with dead cells, and we are waiting on the battery welder. We've received the weld samples, so the welder should come in sometime this week. Once we have that, we will begin matching cells and electrically assembling the prototype pack. To prepare for this, Paul and I have been testing boxes of cells to weed out the obvious bad ones. We're looking to manufacture the secondary enclosure this week, as well as experimenting with various cooling designs. Additionally, Shane and Lennon have been working on our first rapid-recharge charger for the motorcycle. If we're lucky, we'll be rapid-recharging our first pack by the end of the week.

Look for test data and more images soon.

-Mike

2009-06-29T11:04:00.002-04:00

Saturday 6-29-09:
Mike and I started mass testing the A123 batteries. We tested the voltage of about 500 batteries. This is enough to do all of the packs for the motorcycle. We are planning to test the impedance of the batteries after testing the voltage because voltage is easier to measure. The good batteries are around 3.3030 +/- .0050 volts.

2009-06-29T10:47:00.006-04:00

Tuesday 6-23-09:
I finished up the CAD drawing for the motorcycle battery pack in the morning and we had a battery review meeting in the afternoon to critique and improve the design. Many great suggestions came out of the meeting such as ways to improve the battery cooling, ways to simplify the design, and a way to reduce vibration when the battery is on the bike. We decided that we are not going to use FR4 initially and instead are just going to make the battery enclosures out of only Polycarb. We also decided that we are going to have a double enclosure design so that we can put foam in between the boxes to dampen vibration and so that we can use the outer box as a manifold to pull air through the pack. I will integrate these suggestions back into the design later this week. Mike and I are planning to water jet the casing tomorrow or Thursday. We are also going to water jet the tabs for one of the modules this week.

Wednesday 6-24-09:
Mike has a friend who offered to help us water jet so we cut the battery tabs today. They look very good. In order to cut the nickel, we sandwiched it between two sheets of Aluminum. We test fit the battery tabs onto the batteries and they fit well. We did not have enough time to water jet the polycarb battery enclosure today.

Thursday 6-25-09:
Today, I helped Matt look for a spline shaft for the electric motor. We have an engineering drawing of the shaft so I thought it would be relatively easy to find. I spent several hours calling up junkyards and transmission rebuild shops and did not have any luck. We do not know what transmission has the spline we are looking for so I tried to look up the spline by the number of teeth and the outer diameter. In the afternoon, I drove out to the junkyard that Matt went to last week and talked to them about the shaft we needed. The junkyard was called Nissenbaum's Auto Parts. They were very helpful and interested in our project. I first looked for the spline shaft in a dumpster they had that was full of busted transmissions. Then I looked for the shaft in their stock of good transmissions. I thought I found the shaft we were looking for so I took down the information for the transmission. The guy in charge at Nissenbaum's had a good suggestion that we look for the shaft at a transmission rebuild shop. He recommended New England Transmissions in Alewife. I called them up and made an appointment to come in around 9am on Friday morning.

Fridays 6-25-09:

I took the T early in the morning to New England Transmissions. The guys were very helpful and told me I was welcome to look through their shelves of used transmission parts and see if I can find the shaft I'm looking for. I looked for about 3 hours and finally found the shaft that fit the engineering drawing. I took it back to the shop and it did not fit. It turns out, I had been looking for the wrong size shaft. The CAD drawing showed a shaft with two ends and we had just assumed that the one on the left side of the shaft was the one we were looking for but it turns out the right end was the correct spline. So I drove back out to the shop and looked for another hour and was unable to find the correct spline. When I got back to the shop, I walked over to the central machine shop and they said they do not have the right tooling to make a spline shaft. While I was out, Mike finished water cutting the battery enclosure and he partially assembled it. The clear polycarb casing looks very nice. It makes it very easy to see the tabs so in case a battery internally shorts, we should be able to see if the cell fuse has blown. I spent a couple more hours in the afternoon trying to find a machine shop to cut the spline for us. Over the weekends, I will continue to look for the spline and also work on getting the battery pack ready to assemble when the battery welder comes.

Sizing up the Ford Fusion Hybrid

2009-06-26T16:46:00.018-04:00

Dropping an electric bus motor and a Ford 9" differential into a modern mid-sized sedan is no easy task. While we're waiting on delivery of our conversion vehicle (locked in, will finally get here in two weeks), we're doing everything possible to prepare the new drivetrain outside of the vehicle.

So while Kevin is bench-testing the motor and controller system, Matt has been gettting the drivetrain components together that will connect from the motor to the wheels, and he's had an amazing find in picking out a differential that has exactly the gearing we need.

Electric motors can spin at high RPM (ours goes to 12,000) and have a very broad torque range; our vehicle will only need one gear ratio to reach 100mph. To match this speed with the top speed of our motor, we need a gear ratio of 7.3:1. The Ford 9" differential has a huge aftermarket following among the rock-crawler crowd and there are a few companies that make very low gearing for it. Luckily, the lowest one we've been able to find is 7.3:1, exactly what we need. This means we can drive the motor directly to the differential, eliminating the need for a high-speed gear reducer (an expensive piece of equipment that would have otherwise needed to have custom made).

To double check that all of the components will fit before we order them, we took a couple of measurements off of a 2010 Ford Fusion Hybrid (Ford is donating us a Mercury Milan Hybrid, but they're the same vehicle mechanically). We have a few options for fitting the motor and differential into the car; they will be in a T-shape, so the motor will be sitting in the car longitudinally. The motor with the differential coupled to it will have a length of 90cm. The distance from the center of the front axle to the radiator is 65cm, too short for the system. We'll need to connect the differential to the front wheels, with the motor sitting behind it.

However, this mounting also leads to a few other problems: we need to get by the steering rack, a few subframe mounts, and make room for the motor in the exhaust tunnel. Fortunately, the tunnel is already relatively large. We also have plenty of interior room in the car's center console location to enlarge the tunnel with no visual modifications to the vehicle interior. This may also mean connecting the motor to the differential with a CV joint at an angle to not disturb the steering rack; we will find out for sure once we remove the drivetrain. Until then, we're looking to order the differential, gearing and an IRS center housing with CV style ends.

Initial schematics for the BMS circuitry

2009-06-19T16:50:00.012-04:00

Over the past few days, initial schematics for the BMS circuitry have been designed and redesigned. To monitor each battery voltage, we have decided to settle on a difference amplifier topology which will then feed into an Analog to digital converter on a TI MSP430 chip (Fig. 1). The MSP430 will then run an algorithm to sort out the minimum battery voltage within the module and start bleeding the other batteries until they are balanced. The bleeding circuit may be created using an optically coupled p-channel device which turns on an n-channel transistor (Fig. 2). Eventually, individual temperature monitoring for the slave boards will be added and a master module will be designed to include inter-module balancing as well. Please keep in mind that this circuitry is still preliminary and not everything has been simulated to ensure that everything works as expected.

- This circuitry was designed by Bin Lu and Eric Winokur

(figure 1)

(figure 2)