10s BMS for 9 cell LiPo battery setup - wiring diagram

Hello everyone,

I purchased myself the BMS below from eskating.eu. Just wondering how I go about wiring everything up! https://eskating.eu/product/10s-bestech-bms-80a-10s4p/

I’m using this BMS with a 9 cell LiPo battery setup (see diagram below). Which wire should go where?

If someone could be kind enough to alter my image so that I know where the switch (Sw?), fuse, and balance leads should go then I’d be really grateful. There’s also B-, P- and C-. What are these for? @b264 can you help?


Also, on a side note - considering my image the balance lead port goes up to 24. Does that mean I could solder additional ports on in the future and connect a larger battery to it? Not that I would because my enclosure will only fit a 10s4p pack (future upgrade), but interesting to know!

Thanks, Daniel

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@fottaz you have a customer in need


Hi Daniel! Thanks for your purchase.

The 10s bms should be used with a 10s battery to be safe with all kind of automatic detections. Anyway it’s usable with a 9s too.

The balance leads are for a 10s and programmed for 10s max. I would suggest to avoid any modification.

The B- is the negative of your battery, the C- is for negative charge port and the P- goes to the negative LCD and XT60/90 or any connector you will use.

About the two white wires coming out, those are for the on off switch



@b264 @fottaz

Is it safe to say that the below is a suitable wiring diagram? For each cell in the battery pack I understand it needs to go in sync. That means finding out which cell comes first and which comes last, right? I presume I can do that with a voltage meter and the voltage will differ for each one. The smallest number is cell 1, the largest number is cell 3, and the remaining is cell 2. I would test this by placing a wire on the black balance lead and then going between each wire. Correct? Also, does it matter which way round the Sw/Fuse wire attaches to the on/off switch? And why is one called Sw and the other Fuse?


Thanks, Daniel

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@mmaner @Namasaki - could one of you potentially help me please? I saw you both commenting on other threads so hopefully you can help.

With a 9s setup is it correct I need to use a 37.8v charger?

I’m really nervous about getting this wrong :frowning_face::

The max voltage for a li-ion cell is 4.2v, multiplied by 9 you have a max voltage of 37.8v.


Yes you are correct


@mmaner @Namasaki - okay perfect. Is my wiring diagram that I posted above (not original post) correct?

Cheers, Daniel

That bms will not work with a 9s battery. It will not turn on because of zero voltage at B10 Pin.

You’re kidding? There’s so many conflicting answers around here. Honestly I’m so frustrated if that’s the case.

Some people say it’ll work fine, others not. Is there a way to bypass it? People say to leave the last balance lead unplugged?

Some bms are designed for multiple configurations. This bms is designed specifically for 10s. It will detect a fault with only 9 cells. And it’s total values will be wrong as well.


Any ideas what BMS I could use which will allow me to use 9s, 10s, 12s, etc. Multi configurations as you say?

All I want is to charge my batteries easily and have an on/off switch. I can’t afford to pay out for Li-ion batteries at the moment so need to stick with my LiPos.

What about this one?

Apparently all ‘Dumb’ bms modules will work with cells missing as long as it is the last one on the line. Well that’s what I’ve heard from @Deckoz and can confirm this myself with running a 12s battery on 13s bms.

Although maybe this is a ‘smart’ bms? I don’t know, although the seller did say it will work so I would probably go with what he has said

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This is one thing that I’m on the fence about. The seller (@fottaz) says it will work fine with 9s and in another thread @b264 agreed, however now there’s conflicting opinions.

The last thing I want to do is plug it all together and something dangerous happens or the BMS explodes or something.

Theoretically it should not work but you can try it and the worst that will happen is the bms will shut down as soon as you turn it on. It is supposed to read 10 individual voltages and shut down if any of them fall below the low voltage detection value.

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I’ll give it a shot then I think. It won’t cause the BMS to fail and be useless though, right? If it doesn’t work I’ll just upgrade my battery pack sooner rather than later. I wouldn’t want to buy another BMS by running the risk of plugging my current setup in!

Not connecting the 10th cell will not damage the bms. It just won’t turn on theoretically.


Okay. I’ll test it and see what happens!

Just make sure the cell (or cells) that’s disconnected is on the positive end


They’re labelled B-, B1, B2 all the way to B10. I’ll leave B10 alone?