September 9, 2009

DIY Electric Bike

Most electric bikes use batteries with chemistries that have been tweaked for portable electronics (laptops, cellphones, etc). But what if you want something a bit more heavy-duty? Something built for power and durability... How about advanced nano-phosphate power tool batteries from DeWalt? That's exactly what Russ Finley did. Read on for more info and a video.

Homemade E-Bike
His DIY electric bike is based on a $170 mountain bike. As Russ points out in his piece on Grist, his e-bike is very similar to the one that was featured in the New York Times, except that his e-bike cost $1,600 and the NYT one costs $7,000, and his bike probably outperforms the more expensive one...

He writes:

  1. I chose a full-suspension mountain bike frame because the roads and even the bike trails here are so bad. I wanted to isolate the batteries, controller and my butt from the shocks. I also jump off curbs a lot.
  2. I wired pairs of 36-volt Dewalt power tool batteries in series to get 72 volts and then wired each of these pairs in parallel. I can carry two, four, or six battery packs, depending on how long the trip will be.
  3. I replaced my 36-volt, ten-amp controller with a 72-volt, 35-amp version. It also has immediate start, which means the controller does not wait until the wheel is rolling before it puts power to the motor. This lets me get through intersections faster and safer (although I have to be careful or my front wheel lifts off the ground).
  4. I used a rear wheel motor because front wheels here tend to get bent by potholes and fixing one can be expensive if you have a motor mounted in it.

Via TreeHugger
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