Mistake with 10s BMS?

I recently bought a bestech d140 to replace what my old d140 that blew, but they seem to differ a bit.

my older bms had a 8 prong connector, and this one had a 9 prong connector, but that didn’t stop me from connecting it and running it with a loose prong stickin out.

Anyway, this is how I plugged it in, and my fear is now I have an unbalanced P pack because I did something wrong.

Tell me, is this correct, thanks!


@JLabs any help would be appreciated

your balance b- not connected now like this your bms can´t measure the voltage for each serial pack.

how the bms before was working? got the balance b- from the main - on the board? probably, if not I guess you now would already have a short and broken bms.

This new batch of d140 bms has two b-. One on the board like our old ones, and one on the connector. I don’t have the answer but I’m following as I’m having the same problem.

I was planning on using my multimeter to see if the two b- places are electrically common to each other, I.e. 0 ohms when checked across the two. If so, I assume it will be safe to only connect one

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On few of BMS here I see that there is a through-hole for balance B- connector and they sometimes come with full balance count connector (series count + 1) or sometimes they skip that pad because main B- is already connected. Balance and main B- are connected of course (you can see traces on PCB or check with multimeter if you’d like). You’ll be fine.

It’s not the same as other connectors. You will need to attach the B- wire. I would just install the new wires on the battery

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your old D140 probably has the b- internally wired up from the big B- for the battery lead. it’s safest to wire a new b- lead from the battery to the b- balance lead.

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