I have a slightly unusual problem. I live in China, and my US employer says I can't have a gas powered bike. I can however have an e-bike. I did have a 48V 500W bike that was ok, except I really want to explore the mountains around here more and it just didn't have the range after climbing 1,500' in elevation. I recently bought a different one, a 1200W 48V this time (and you can hopefully see a photo of it). It runs up roughly 6% grade mountains at about 19mph which is good. But when I put on the extra 48V 20ah SLA battery pack I bought performance gets quite a bit more sluggish.
What do you think about using a 48V roughly 100A alternator driven by a small 2-stroke engine? I know there's no such thing as a perpetual motion machine, and I know there will be some efficiency loss, blah, blah, blah, but all I want to do is to put a constant charge back into the batteries as close to what I'm taking out as possible. I would hope the entire arrangement would weigh about 30 lbs as opposed to the roughly 60 lbs the extra batteries weigh. Does anyone have any experience with this or have any knowledge that could help?
P.S.: My 1200W 48V scooter,with front disc brakes, cost me $612. A new set of SLA 48V 20ah batteries for an extra battery pack was an additional $105, but they may not be as good as the ones sold in the US. The bike is pretty decent quality though and is one of the better brands here.