Booster Battery

GypsyTreker

Well-Known Member
I'm looking to use a 36v 10ah Lipo "block" as a booster battery for my wifes 20" folder bike. Its my understanding ,as long as both batteries are toped off, I can simply run the discharge off the booster to the charge port of the bikes stock battery ( parallel ). Naturally I would have to adapt the input wire to fit a Silverfish 3 prong input. These batteries are available on eBay for under $100 shipped. I have to assume they are sans BMC. Anyway thoughts, advice, etc?
 

harryS

Well-Known Member
Micah Toll put out a video recommending this. I tried it briefly. It depends on the charging circuit, but most charging circuits have different grounds, so the booster can only charge the ebike battery when the motor isn't running. You're not sharing the load like when you really put two packs in parallel. Still it does charge the pack and extends range.

Those $100 packs do have a BMS, otherwise they would go up in flames when they get unbalanced. It might be a good use for them. since they won't have to push much current. Still, I don't trust cheap batteries, mainly vecause of fire safety. It's a given they won't last as long.
 

GypsyTreker

Well-Known Member
Micah Toll put out a video recommending this. I tried it briefly. It depends on the charging circuit, but most charging circuits have different grounds, so the booster can only charge the ebike battery when the motor isn't running. You're not sharing the load like when you really put two packs in parallel. Still it does charge the pack and extends range.

Those $100 packs do have a BMS, otherwise they would go up in flames when they get unbalanced. It might be a good use for them. since they won't have to push much current. Still, I don't trust cheap batteries, mainly vecause of fire safety. It's a given they won't last as long.

Thanks Harry. I had actually saw this on Micahs YouTube. I can't justify $300 for a battery that may never be required to give as much range as the main battery, an extra 10mi would be nice. So I think, if I understand you correctly, this battery ( the booster) will only work when off (like an aux cell phone battery).

I did look @ Micahs plug and play kit and cells to make my own booster. All the sudden the Ecotric Silverfish looks like the more practical way to go. I'm not a DIY type but not afraid to try stuff that makes sense.
 

harryS

Well-Known Member
Guess that's true. The booster is equalized so nothing happens til the main pack drops down a bit,, Maybe I'll hook one up to my silverfish and check it with a wattmeter.
 

GypsyTreker

Well-Known Member
Guess that's true. The booster is equalized so nothing happens til the main pack drops down a bit,, Maybe I'll hook one up to my silverfish and check it with a wattmeter.

It would be great to have a qualified opinion on this. I mean realistically, a 6-8ah 36v booster would work and be compact enough to velcro to her back rack. My 26er came with a spare, the deal clincher no doubt. Fact is, with a modified discharge cable (2) it would suffice if I simply was first to use up more battery as she often tends to go "motor- less" for the sake of a workout and carry this "booster" for both bikes.