Originally Posted by Razmo
Hmmm, it sounds like maybe a generator may be the better choice?
Back in the 1980's I did rewind an automotive generator, and working with a microcontroller circuit, made it into a constant current charger for 38 series Nicad cells. The system was set up with a five ampere charge rate, and when the nicad cell's voltage dipped by about 2%, it killed the engine. The maximum charge rate was limited by the 3 horsepower Briggs engine. Much higher than five amps, or 38 cells, the engine stalled.
Would not take much to make a Lipo charger out of it, but I'd have to rewind another alternator for higher current outputs. A pair of 120 Ampere Hour deep cycle lead acid batteries is a lot simpler, and a lot quieter!