How to balance charge a 12s battery pack

ESK8 Electronics
21

My old RC chargers didn’t go above 8S. Here is what I used to do to charge higher packs:

You need to have 2 independent batteries:

Battery 1: Main negative needs 2 wires, one connected to ESC connector ground and second to charging connector 1 ground. On the positive side, you need a single wire to charging connector 1 positive.

Battery 2: Main negative needs 1 wire connected to charging connector 2 ground. On the positive side, you need 2 wires, one to ESC connector positive and one to charging connector 2 positive.

To charge, you connect charging connector one to one charger and charging connector 2 to another charger (or 1 per channel on a dual charger)

To turn on, you need to connect charging connector one positive to charging connector 2 negative. Yes, it doubles as a loopkey.

You also need one balance connector per battery.

I’ll draw a diagram in a few minutes.

E: Here it is,

image
image3264×2448 2.08 MB

So battery 1 is the top row of cells and battery 2 is the bottom. I bought one black and one yellow set of XT60s so I would not confuse them when plugging in the loop key, but it would not matter if you did. The board would simply not turn on.

You also do not need a connector between the ESC and the battery but I had one since it was just a temporary solution

3 Likes
22

Nice artwork :slight_smile: If you look at the photos I posted above, that block is the loop key, and it blocks the balance ports. It serves as a mechanical lockout so you can’t connect both.

23

That’s a perfect solution! I’m gonna do that, thanks!

24

So if I leave the loop key in, it’s one pack and I charge from one port, and if I remove it it’s two packs and I could just a balance charger on both charge ports. Right?

At least, that’s what it looks like to me… Could I use one 12s BMS or would I need two 6s BMS?

25

I did this on my build. I made 2 6s4p and have all connections on the outside. Loop key connects the packs together in series.

26

Ish…

Yes, you could charge from the ESC port but you would not be able to balance unless you made a harness that joined the two balance plugs.

Yes. But if you have a harness joining the balance plugs together and try to charge, you would blow up something.

As long as you disconnect the BMS harness from the battery to charge the 2 packs individually, you can use a 12S. Having 2 6S BMS would overly complicate things

1 Like
27

If you do 12s BMS don’t bother with all the rest of this – it takes a surprising amount of room to make all these splices and connections. Just check cell voltages somewhat frequently with a volt meter until you develop some trust. IMO.

1 Like