6s bms with 6pin balance, instead of 7

Hi, I bought a 6s bms from hobbyking, but it differs from the photos. In the photo, there is a 6 pin and in some a 7 pin balance connector, but irl it is a 6pin connector. Therefore, the b- pin is blank. Should I just connect all the balance leads from battery to the bms and leave the ground out?

The 6s bms and the connector is shown here.


It looks like B0 spot (balance lead which goes to battery main negative) is empty. I have seen it on some bestech bms. First balance wire on your connector should be connected between 1st and 2nd group and your last balance wire should finish on battery main positive (after last group). Just make sure that you connect battery main negative to B- on bms first, before connecting balance connector.

Okay, actually, I have used this bms for awhile, but I left the negative out altogether on the balance connectors, so the b1-b6 corresponds to the cells on the batteries. Because b- on the balance connectors should refer to the b- on the battery main lead on the board? The cells are balanced fine this way. Or should I still connect cell 6 not to b6 but to the main lead?

I am not sure if I understand. B- on your bms goes to xt60(or xt90) negative or directly to battery negative, right? And no other balance wire goes from that spot on battery? Do you have any instructions how to wire this bms?

I have this diagram.

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Just like what I desribed in first post. What do you think you did different?

Maybe I misunderstood you. Should i connect all the positive balance leads to the balance connector and leave the negative balance lead just empty? Or should I connect it to the battery main negative? Think there’s no point?

hm there is no positive or negative balance leads. They go between groups, so they are both positive and negative (if that is correct term?). Your first balance lead goes between 1st and 2nd group, 2nd lead between 2nd and 3rd group, 3rd lead between 3rd and 4th group, 4th lead between 4th and 5th group, 5th lead between 5th and 6th group, 6th lead after 6th group (aka battery main positive)

Forgot to mention i use lipos, that are 6s. How should i connect it then?

Should i wire it like this then?

Your 6s lipo should have 7 pin connector, first lead being probably black and last wire red. Black lead goes nowhere if your B- plate on bms is connected to lipo negative (aka xt90 or xt60). If it’s not, then black lead goes to B- plate on bms.

how did you get + on black wire on this diagram? :sweat_smile:

Nah, its a cross, that i would just leave it blank :slight_smile:

Well the connector itself is 6 pin, altough the pcb has 7 pins on the board.

No, B- on bms has to be connected to battery main negative. It could be through black balance lead from your lipo, or from negative side of xt90 (or xt60) from your lipo.

But your connector on lipo is 7 pin, correct? Take some photos of your lipo so I could see connectors too

Yes, the Lipo has a 7 pin connector.


The bms however has a 6 pin connector.

On lipo on balance connector, you see first, black balance lead? That goes nowhere if thick black wire from lipo goes to B- on bms. If you don’t connect thick black wire from lipo to B- on bms, then you have to connect thin, first, black balance lead from lipo balance connector to B- on bms.

Okay, that’s actually what I had been saying from the start :smiley:

Thanks a lot.

Finally we got each other :smile:

Took some time :smiley:

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