Completely solar powered bike?

LOL. By the time I get to the top of a hill, I'm ready to coast. Regen braking would put some of the power expended back into the battery. But, it would have to be a LONG hill for me to be peddling on the way down!
 
Is it possible to create an e-bike with a thin solar array attached to the back that is always charging the battery?

Yes. For thin film arrays you can get about 5 watts per square foot. Crystalline panels can get closer to 10 watts per square foot. Figure you can get 9 square feet on the back of a bike (3' x 3') so you'd be looking at 90 watts max. (Naturally that's when it's 50F out, with sun directly overhead and the panels completely unshaded.)
 
Loquin hit on what others have found on other forums. Over on Endless Sphere, The question of pedal generators comes up often. Its been calculated to be only 50% as efficent as just pedaling the bike at best, and many applications are going to be worse. meaning if you could go 20 miles on your bike by pedaling, by using a generator to charge a battery and run a motor, you have reduced your range to 10 miles.


"But wait! I didn't mean charging the battery exclusivly, I only ment using the generator to extend my range. I'd charge the batteries at home!"

Right. Same principle. If you could normaly go 20 miles on battery alone. and you also have the fitness level to pedal 20 miles, by using the pedals to generate power, you could extend your range to at best 30 miles. HOWEVER, if you skipped the whole generator mess, and just pedaled along with the motor, you would extend your range to 40 miles.


As for the solar charger, Ypedal hits upon the best solution in another thread. it just isn't practicle to carry a pannel big enough to charge the battery during the day. Solar panels just don't have that much output for there size. But a home base pannel, charging up some car batteries all day long, could be used to recharge your bike over night. Such a system could also be used for emergancy power around the house, so it has added benifits.
 
You could also ride the bike to work on the battery, unfold your solar panel array, and have it charge your bike's batteries all day long directly, at the 90 wH rate. 8.5 hours * 90 wH = 765 wH. (minus the charging losses) Then, ride home on the batteries & plug into the wall there.
 
Re, Solar Bike: It's been in the back of my mind to use a solar panel as a top for a cargo box on the back of my trike (Atlas Industrial). Or a trailer top for a two wheeler. A few hours parked in the sun would certainly give you a few miles range.
 
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