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electric bicycle motor? Answered

okay, Im thinking of turning my bicycle (a "Quasar Bounty") into an electric bike.  it already weighs about 30-40 lbs. And I want it to go at least 30mph. Can someone please suggest a motor I can use, and what battery I should use?

Michael McPherson (mmcpherson4)


you can go to http://www.hobbyking.com and look at their turnigy motors. i recomend the blue motors they have and the turnigy v-spec motors... i would expect to spend around 23-50 bucks on a motor.

outrunner motors have more tourque

inrunner motors have more rpm and are a bit cheaper.

you probably want an in runner motor. also you need to multiply the volts (V) by the amps (A) to get the wattage. you need at least 500-1000 watts. a size 36 motor or larger should work. then you need a way to control it. you can use an ESC (electronic speed controller) or get a motor-shield with an arduino.

its pretty much building an engine/motor for a large rc car, but sticking it in a bike :D

or an ESC + an Arduino programmed to generate the adequate pwm output to the ESC. :-) I think a motor shield would suffer a little to provide, say, 40Amps to the (I would choose) outrunner. The Arduino libs already have a Servo routine that would wire almost directly a PWM output Arduino pin to the control pin of an ESC to control it properly.


8 years ago

I've been thinking of using a 36volt drill as a boost motor. This is probably a bit underpowered for use on its own but it might be a good, cheap(ish) lightweight system to give you that little extra kick when you're late for work or a hill is feeling a little bit to steep or a destination a little to far. A drill motor might help you turn it up to 11 so to speak.

The thing about DeWalt 36volt drills is they use fancy lithium batteries made by A123 Systems. These batteries are small and light enough to carry in your backpack, they sound like they are somewhat abuse resistant and I think they are mostly non-toxic. And you can get them in any hardware store. You might even be able to use the trigger as a throttle.

Hmm, I really should experiment with this. Has anybody else tried using a drill for a bicycle motor?

The trouble with drill motors is that they have a very high RPM, low torque (too low to power a bicycle anyway), and the battery life is going to be pretty poor, not to mention that running a drill for that long is probably going to be bad for the motor. While I suppose it would be possible to gear a drill motor down to a more usable level (400-500 RPMs), you would need a heck of a transmission for that. Even then you would lose a lot of power in the conversion. I've been doing a lot of research on this subject and seen everything from electric chainsaws to car starter motors used to power bikes, but as far as I can tell the best thing to use is a 12-36V 500-1000W motor. These are commonly found in electric scooters and can be purchased relatively cheaply online from websites like calgarc suggested. As for batteries, make sure whatever you use is made to be almost fully drained and recharged, or you could end up ruining the battery. Normal car batteries are NOT good for this sort of thing, as they are not intended to be completely drained. Keep an eye out for "Deep Cycle" batteries, as these are meant to be fully discharged.

Is there any reason why couldnt use drill batteries to avoid the hassle with lipos or wiring up a123s when using an outrunner motor ?

I ve been contemplating drill motor myself , but the rpms are far too high on most of them , as i only need to go 1- 4 mph maxium to assist with walking on a knee walker I have.

The the best motor to gear ratio see is the Matika 451 18v , it has all metal transmissions too