Some help with a battery

Hello, I’m not as confident as I’d like to be about this. I’ve searched about and couldn’t find a definitive answer so I figured I’d ask here. Does anyone know if the red wire is the first positive wire or the ground wire? My instinct is that it’s the first positive but I don’t know for sure.0213191805_HDR

The red wire is the last positive (3rd cell) :wink:


  1. B-
  2. B1+
  3. B2+
  4. B3+ (red wire)

I concur if it makes you feel any better. Not that Im an expert compared to @rich, but I’ve recently burned up a charger so I understand your hesitancy.

Consider getting a multimeter :+1: :zap::zap::zap:

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I concur it is the last. But please try and get your hand on a multimeter any would help specially in this sport or hobby

Thank you guys for the help. I’m making a 12s LiPo with a BMS I picked up. From what I can tell there is 13 wires on the BMS and from what I’ve learned here I am supposed to ignore all the B-'s except for the last one.

Pics or it didn’t happen

I am currently doing similar shenanigans image

What does your BMS look like?



I presume these are the parts still? image

minus the 100a anti spark. I’ve decided to go with a loop key instead

Had to take a hiatus on building cause life gets in the way sometimes but I’m back to trying to get this guy done

Are you hardwiring (soldering and cutting stock leads) this or marking an adaptor?

Making adapters so if a battery dies it will be easier to swap out. That being said I am soldering the stock leads from the BMS(the white wires) to the clips for the adapters instead of crimping and adding more wire in between connections.

I’m also not to sure if the range will work out for me with these only being 6000MaH so I don’t wan’t to hardwire.

if you ever have doubts, use your multimeter and test between the connection. if the result is 0 volts between red and red that means its the same. if it’s 3.7 ish volts then it’s between cell one and 2 for example


Sorry, I am not an engineer. This configuration doesn’t cut up your leads. Your current is controlled by the ESC (80A in this case).

@Namasaki has several great posts that detail these set ups.

Don’t take this as gospel, but I am fairly certain its correct.

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This is pretty much what I was planning. they’re 13 wires coming out of my particular BMS though. That 13th is supposed to be the last B- correct? Or do I have an extra lead for some reason?

It’s the first B- (B0).

Just for understanding, B- (also called B0 on balance wires) is the negative lead of the first cell of your battery. B1+ is the positive of the first cell, B2+ is the positive of second cell and so on.

That’s why it’s important that your first lipo is battery negative and the last and fourth in series the main battery positive.

I changed the nice diagram of @Arzamenable to your needs


On the PCB of your BMS should be printed which cable is which connection.

There are different types of BMS available that’s why many are confused and shouldn’t just copy diagrams which could be wrong for their setup. If you understand how “your” BMS should be connected then you can draw your own diagram and are ready to go.

In any case you must connect the main battery negative to B- before connecting the balance wires to BMS.

And as mentioned, use a multimeter before plugging the main balance connector. Negative on B0 or main negative, then start with the positive tip on B1+, then B2+ and so on, every step should increase the voltage about 3.8V (or whatever your cell voltage is) until you reach your main voltage at B12+.

:joy: Thanks but would an expert cut a 6s balance extension with scissors while it’s still connected to the battery? Damn, that was an instant adrenaline rush from the hissing, popping and sparkling sensation.

This has been wildly helpful. I would have had the battery order backwards. I thought where its marked the number 1 battery would have been in the number 4 spot due to thats where the positive cable goes to the ESC’s

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Meaning i was about the put that ground lead in the wrong order