Triple checked all of the balance wires and as soon as the battery is connected the bms gets hot and starts to smoke.
It’s a 12s battery and bms .
Help pls

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What diagram did you use and where’s the backplate?

I’ve only ever had that happen when it was wired incorrectly

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I took the back plate off to see where the smoke was coming from . The voltage of the balance wires goes from black B0 (the least) to red B15(the most).
The diagram and instructions are as follows


I reckon you got a dud bms dude

Tried it again with my spare 14s bms soldered together
B3/4 B8/9 to make it a 12s and plugged it in quickly again.
Same thing happens .
Totally confused .
Tried reversing all of the wires on the 1st one and smoked heavily so they’re defo the correct way round

The bms isn’t configured for life-po4 yet but I can’t see that making a difference as they’re lower voltage

That doesn’t matter. If I understand your last post correctly you made 2 separate bms get hot and smoke. This 100% means your wiring is wrong


As I said. The bms balance wires go in order from negative to positive and up in voltage from B0 to B15.
I tried flipping them round on the first (now broken) bms and it started smoking instantly.
How else have I got it wired wrong?
B- to battery negative.
Balance wires in order.

The only thing I’ve not done is connect the charge negative but I can’t see how that would affect anything.
I’ve used LLT bms’s for various builds and never had an issue. I’m totally perplexed

I always connect that one though. But it’s still strange. The chance of getting 2 dud BMS at once is not super low, it’s possible.

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I’m kind of thinking maybe it’s the balance wire loom going into the bms. I’ve asked them for a diagram of the correct pin out .
If it’s not that then I’m stumped

that does seem weird.

this suggests the voltages are in the right positions.

and this suggests the bridging matches the wiring loom.

maybe the 12s is a dud. or bridged wrong. and your self converted 14s is wrongly converted… ??

your 12s looks bridged the same way as my 12s:

Maybe double, tripple check that the voltages are in the right order and the right magnitude.

Thx. Yep I have triple checked my voltages . The cells are mounted to a pcb which makes it even less likely for me to mess it up. I have checked the balance
Wires about 100 times.
I’ve ordered a Daly smart LIFEPO bms so will c what happens when that arrives.
If it blows up. I give up

yeah that’s confusing. i can’t spot anything wrong either.

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I followed the bridging on my 12s for the 14s. The only thing I can think is the loom is wrong even though it matches up. :man_shrugging:t2:

I dont think the new 14s ones follow the same convention

That’s why I bridged the pins so it’s like the 12s.
I assumed higher S count bms’s just unbridge the pins etc

Is it one of the newer 14s ones? They follow a different pinout.