Originally Posted by
trekker pete
While we are talking genies and batteries, I was wondering if any of the hub genies out there can provide enough torque to provide noticeable assistance. I'm not looking for a 30 mph ebike. Just a little extra something to help on short hills. You might also be able to reclaim some of that precious kinetic energy through regen on the down hills. Maybe a really big ass capacitor might serve well in this application as you can charge/discharge at pretty high currents for short periods.
It takes about 2.5 hours to recharge 4 AA Ni-MH batteries with a bicycle dynamo. Your not going to get any help going up a hill with a tiny little motor which could be powered with 4 little AA batteries. A modern bottle dynamo requires about 8-watts of your energy to produce 3-watts of light. A hub dynamo is a little better using about 6-watts. I hear some people complain about even this very small additional drag. I can't imagine the pedal power required when adding a larger generator to provide enough current to recharge batteries large enough to power even a very small 250-watt hub motor for any length of time.