Thursday, May 28, 2009

12V Measurements & DMOC Parameters

Shane and I measured the 12V power consumption to determine if the 12V supply (DC/DC converter) is correctly sized (it's rated for 22A).  One thing of note right away is that with the car turned off, we're still drawing 0.3A... probably the cRIO and the SOC display, which right now are on all the time.  That should get fixed, the car should operate reliably using just the ignition key.

Off: 0.3 A
On: 2.5 A
Wipers: 8 A
Turn signal: 5.2 A
Hazard: 0.5 A
Brake: 0.4 A
Running: 1.7 A
Reverse: 3.1 A
Headlight: 9.6 A
High Beam: 11 A
Fog Lights: 4.9 A

You can see the big difference the LED bulbs made: compare the LED brake lights or hazard lights to the incandescent backup lights.  The 5A from the turn signal must be an anomalous reading, or there's something funny going on with the blinker circut, we'll have to investigate further.

The results are we should be fine during daytime driving: we draw about 4A, with the display possibly bumping that to about 8A.  We'll have more issues doing nighttime drives in the rain, where our draw is close to 20A between wipers and headlights.  Worst case would be driving on a rainy night and breaking down on a deserted road (nevermind all the other issues related to this scenario), after trying to backup to the last exit without success you leave it in reverse and rest your foot on the brake, with the high beams and fog lights on, you turn the hazard lights on and crank the radio up to drown out the sound of the the wipers and the pouring rain while you wait for help to arrive.  35A.

We also discussed how the "frankenstein" switch might be replaced by a smaller switch, to open up more room in the back.  The only high current connection through it is the charger (~10A now, hopefully 30A someday), the primary issue is few switches are rated to break 30A DC (since you could get a self-sustaining arc in the switch), though hitting the E-stop would correctly break the circuit using the contactors, and actually, breaking the HV connection to the BMS will cause the contactors to open anyway.

We also looked at the DMOC parameters, trying to figure out what led to the interesting motor torque curve mentioned last week.  We didn't come to any conclusions, but will keep looking into it, there are tons of undocumented params.

Tuesday, May 26, 2009

Electrical Boxes Installed

The first step in the electrical system overhaul got done today, the front and rear junction boxes got installed.  Next step is to get the get the cable branches installed nice, and start putting holes in the boxes for the cables to run into.

Saturday, May 23, 2009

Motor and Controller Arrive for elEVen

Radu dropped off the motor and controller for the elEVen in the lab today.  

Wednesday, May 20, 2009

Display & Motor Data

Kent and I worked on the touch screen display today, the panel powered on and runs windows CE.  The next step is to get LabView software running on the console, and to figure out how to get the cRIO and touch panel talking with each other.

I took a look at the motor data from our 5/3/09 test drive, I superimposed it over the motor spec from Azure.  Interesting thing happens, the torque starts higher than rated, but at about 1000RPM, the torque starts dropping off.  In Azure's specs, the constant torque range extends to 5k RPM.

Saturday, May 16, 2009

Somerville Green Living Fest

Saturday we took the car to the Somerville Green Living Fest.

There were a bunch of other 'green' vehicles there, including a biodiesel car and a school bus/RV converted to run on grease. A guy from Herb Chambers BMW was there with a diesel and Prius, and suggested we talk to Herb about helping the team, since he owns a Porsche dealership.

Right about closing time, it got cold and windy so we packed up in a hurry in case it started to rain. We had some issues with the transmission (and possibly other things) on the drive home. Each time we started out from a stop the car seemed to behave differently, sometimes it would have nice pickup and other times it would be really sluggish, as if it was still in second. At on
e point, we were driving like 35 in "first" gear, which seems totally unlikely given the motor is limited at 3000 RPM right now.  Unfortunately the laptop's battery was dead so we didn't get any data to figure out if it was purely a transmission issue, or if the DMOC was throwing a hissy fit, that shouldn't be a problem in the future, once the data logging is built into the cRIO.

Friday, May 15, 2009

Porsche Passed Inspection

On Friday, Irene and I took the Porsche for its annual state emissions & safety inspection. It passed with flying colors, the mechanics were so amazed by the car they couldn't stop gawking at it.

Thursday night, Tyler, Ben and I got it ready for inspection. They hooked up the windshield washer while I worked on the backup lights.

Sunday, May 3, 2009

Test Drive

Went for a test drive today.  The waterproofing team had removed the engine hatch without replacing it or installing their cover, and there was a chance of rain, so we covered the mid batteries with cardboard and Irene's *orange* duct tape :)  

After a small detour, we ended up purchasing walkie-talkies to keep contact between the Porsche and chase vehicle.