Yes those are bestech, best brand for bms? I can’t say, but I know a lot of people use them and I haven’t seen any issues. That specific model has an e-switch so there’s no need for an anti-spark switch or loop key.
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Oh well I really love that, I was reading that thread where all the anti spark units were all failing…
There’s a few approaches, but BMS will be more convenient.
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12s balance charger. there are a small handful.
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break connection at middle, charge as 6s
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put 12s bms on charger side
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find a separate battery balancer
For #1, you can do tricks, like breaking the series connection with a loop key that’s panel mounted.
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Stand alone E-switches are notorious for failure but the Bestech built in E-switch is dependable
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Yep, BesTech BMS’s. The best BMS’s in my opinion.
So you can make 12s battery and outputs 48v and if you hi jek between the 6s cell make additional line of balancing cable and charging port, now u have 1+4= 5 power port
it is a bit complex system hard to describe in words. I think I can build a switch btween 12s and 2*6s for additional safety
but u can charge quick safe and cheap. and you dont have to open the box ever.
drawback is now you have 4 ports outside instead of 1. and if you dont have cover ports can damage and corrode from water.
I should mention, you don’t have to break the connection if you charge 6s at a time. If you try to series or parallel charge two 6s packs that are still connected 12s, you’ll probably see fireworks, from the common ground somewhere.
here’s a picture of a really well done split 6s trick (might not be 6s) with ebike. Follow the link in the link for more detail
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So basically, I shouldn’t worry about it as long as I have a proper BMS then?
I guess I could build 2 packs each with its own BMS and then connect them with one of those 3 sided series connectors, and each charging port would be able to balance, I’d just need to connect an extra set of sensor wires for each pack to also be hooked up when balancing. So there should be a set going to the BMS and another could be mounted to the enclosure for balance charging.
BMS is not magic – you should always worry. There are many failure modes BMS won’t help you with.
And I’ll caution once more (I couldn’t understand what you were saying). If you try to charge 2 subpacks that are still series at the same time (with 2 chargers, or with parallel charging), it’ll most likely blow up due to shared ground.
Well yeah, that’s why I’m asking about balance charging, without the BMS. If I thought that then I wouldn’t concern myself with this stuff.
If I was to have 2 separate packs with 2 separate chargers, I would connect them with a series connector, but disconnect them when charging. (to avoid the shared grounding)
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Do any of you guys run a 12s, and if so, how do you charge… or rather, do you charge it any differently than normal?
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,
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
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Nice artwork 
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.
That’s a perfect solution! I’m gonna do that, thanks!
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?
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.
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
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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.
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