Friday, August 21, 2009

Electric motorcycle update

A couple years ago I built this all-new electric motorcycle - for $3,000 - using parts available on the internet:
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!).


  1. Hello,

    I was just wondering the total voltage of the new lithium pack. I see 10 cell in parallele so 23A and 6 of those pack. 6 x 3.3V = 19.8V

    He said one module, so this mean there might be 4.

    4 x 19.8V = 79.2V so 240 cell. ~2400$

    The original pack was 72V.

    Charging the pack is the most complex part to make.

  2. I was able to read this on the blog

    "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."

  3. I recently came accross your blog and have been reading along. I thought I would leave my first comment. I dont know what to say except that I have enjoyed reading. Nice blog. I will keep visiting this blog very often.