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.
Thanks,
Mark
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It can work, but only if the generator is very lightweight. When I tried it, the gas generator I have, 800 watts, was too heavy. It weighed almost 40 kilos. The weight of it cost so much perfomance that for me, it did not work. Though it costs a lot of money, some lighter lifepo4 batteries to add to the range would work better, and not weigh so much. If you can build a generator light enough, it will work. It's worth a try if the parts for it can be found cheap enough.
Be the pack leader.
36 volt sla schwinn beach cruiser
36 volt lifepo4 mongoose mtb
24 volt sla + nicad EV Global
Dogman,
What kind of generator were you using? AC or DC? Was it home made? I am wanting to try about a 35cc weed eater engine turning a 48V alternator through a belt drive system. I'll need to build a custom rack too, but I don't think it'll be too heavy since trimmer engines are light and alternators aren't that heavy either. I think I just need an engine big enough to handle a 10-15A continuous load on the 48V alternator.
Formerly the proud owner of a Wanbaoulu (Marlboro) "Exquisite Article" model 500W scooter, currently the owner of a Lima 1200W 48V scooter
Look up "Series hybrid", thats what you are trying to build.
You will probably be better off using a smaller battery and a smaller generator.
If you try to produce all the electricity on the spot, then you need a generator capable of producing the power needed for acceleration and hill climbing. It will then be running at inefficiently low load most of the time.
Use the smallest battery pack that allows you to do your regular commute without generator, and add a generator that produces the AVERAGE power requirements when you go on an adventure out of town. The generator can either run to charge the batteries when you have stopped, which would allow charging segments of your battery at 12V or 24V; or if you want to run it also during riding, then it needs to produce the full 48V of your pack.
This information may be used entirely at your own risk.
There is always a way if there is no other way!