Backfire G2 battery pack troubleshooting


I have an old backfire G2 spare battery (no name chinese cells 10s2p) that was laying on the shelf for a few years (+/- 3.5years), and i decided to try and build something with it.
Miraculously the pack does not seem dead yet (still at 36V and the p groups are well balanced), but for some reason i can’t get it to power my esc (maker-x go foc dual).
When i read the voltage before the bms i get 36V, but i get a really low voltage (+/-0.3V) on the main connector, after the bms.

Does anyone has experience with this kind of chinese bms ? Is there some kind of safety handshake between the bms and the esc to get it to deliver power ? I know boosted used to do this, so maybe it’s the same here or maybe the bms is just dead.

Any idea ?
If nothing works i can still try to bypass the bms, but i’m not sure it’s a good idea with those cheap chinese packs.

" Is there some kind of safety handshake between the bms and the esc to get it to deliver power "

I’d bet on that.

Can you get the serial/model number off the BMS? (kind of looks like “gw43-vd4”, but I get nothing)

Still, though, I don’t understand why it has gone into safety mode. That voltage is fine.

Could not find anything from gw43 either, not sure what it is supposed to be. I managed to get this from the other side of the bms, dunno if it helps

I’m not finding anything, kind of surprising considering how many of these they sold. Can you replace a BMS? There’s lots of info on “waking” sleeping lithium cells, but I couldn’t find much on BMS’s. I think you might need something like an FTDI programmer, but it could be more simple than that. Try the other question threads, perhaps.

Well, i could try, i’d have to resolder every balance wire, but it’s still better than nothing.

Bypass the discharge.


You can just use these solder joint butt connectors:

You want to find the smallest ones of course. You want to label each balance lead you cut with the voltage you measure from it: 1 - 10. Then there will be one, I think, additional wire- ground. How many balance leads can you count? I think sometimes there’s an additional 12th wire on 10s BMS’s, and it would just go to the positive battery terminal.

It will be easy to figure out which voltage is what series because it will be sequential, of course.

I thought about that, not sure how safe it is, but it sure would be easier than replacing the bms.

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That’s what I would do, bypass it. I’ve been running no BMS on my one board for almost 2 years.

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Safety?you throw that out the window right meow. Just the discharge side. Keep charging safe.ish.