View Full Version : Electric bike optional upgrade

02-08-2008, 11:54 PM
Hello, This being my first post, I just want to dive in with this suggestion for a different approach to an electric bike. BTW I have seen an advert for a Chinese electric on the market in one Harbor Freight catalog. It was listed for around $300 shipped with battery and charger, claiming a range of 8 to 12 miles. (Not too impressive). Yet on seeing that advert, I started thinking about alternatives. This seemed possible; a dynamic bike with a combination motor-charger and a battery that would charge on downhill and flats, and motor on flats and uphills. Early garden tractors, Cub Cadet, had a combination starter-generator on board instead of two separate units. I priced one for curiosity, a bit expensive, but possibly could have been adapted. The dealer did not recommend this mod. Yet the idea of using the older DC wound started-generators and a high amp battery (maybe even a solar panel), seems tempting for working out a dynamic design which requires no charger and waiting time for power replenishing. That simply riding with the terrain and gravity on a sunny day could get one down the road a lot further and easier. Food for thought.

02-14-2008, 11:50 AM
That is a feasible idea, but I dont think the lawn tractor stater-generator is the way to go. It is very heavy. There has to be a smaller variety out there somewhere.

02-14-2008, 08:47 PM
Regenerative braking is not included on many small EVs as the gain is almost zero.

Maybe as battery technology advances, the 30 seconds of downhill terrain might make a difference. Right now, that is hardly enough to even start the charging process.

Those super capacitor pulse charge batteries look interesting.



03-08-2008, 03:59 PM
This is also my first post. I actually came your idea independently awhile back and wondered aloud in an independent bike forum why the idea might not be viable. There was a distinct lack of interest in following up my idea. Doing my own pro/con I can see these right off: first the pro's: motor output needs no clutch or other gearing or transmission to get the power to the ground. Next, motor output if sufficient can charge the battery at anytime, not just when going downhill or on level ground. The con I can readily see is weight. The generator unit will be heavier than just a motor and the penalty is a little harder to justify because the drive motor(s) could also be generators so in effect you are carrying around one more electric motor than strictly necessary. Another problem is voltage. Most generators in the U.S. are 12V devices. Most bicycle drive systems are 24V at minimum. Still, I have a design goal of using a trailer mounted generator to power a number of different all electric or pedal/electric bicycle designs whenever the additional range of the gasoline generator is needed but able to disconnect the generator when local outings are considered.


09-29-2008, 08:21 PM
The idea might work if you put the generator on a trailer. I know my Gas welding machine will put out 10,000 watts and will run for about 12 hours on 8 gallon of gas.. Just think of all the electric motors you could use, Now convert the welding machine to burn HHO and you could go forever only stopping to fill up with water to turn into gas... I already have a HHO generator for my Torch, but am a bit scared of trying to connect it to my weldine machine as the HHO gas burns real hot and I don't need my Lincoln turning into a pile of molten metal, so that I can save a few dollars on gas....