DIY Solar Panels

i live in an rv and it gets really cold im trying to figure out how to keep the reservoir battery charged without using up the gas can i charge the battery using a homemade pedal generator and if so can you explain in lam-ens terms on how to go about making one

i made a peddle generator. i used an RV motor. Any dc motor is also a generator. I just got a rubber wheel from the hardware store and put it on the shaft. People are always giving away exercise bike. They buy them but never use them. You can peddle up to 80 watts while carrying on a conversation or watching TV. bobmalcomb@aol.com