marine7 said:
But when I connect the balance wires to the charger to balance the cells with up to 1A balancing the BMS get ver hot.
That's because 1A at 4.15v (presumed balance voltage) is 4.15watts of heat, per cell. At 3s, if all balancers were on, that's 12.45watts of heat total. Soldering irons start around that wattage (able to melt solder), so it's no surprise that it is hot. It would be completely normal.
Especially if you are not using the BMS to shut off charge when a cell is full (which is what it is designed to do, to protect you from a fire or damaging the cells).
If the balance voltage is a lower voltage than your charge voltage / 3, then it's going to be trying to drain cells all the time once it's past that point, and it will also do this once you reconnect the balance plug, because the cells are already above that point.
Why Im doing this I don't want to relay on the BMS to balance but would rather want to get the active balancing done while charging.
Well, if you don't want the BMS to balance, you'd need to use a charger that directly charges each cell group, which will require thicker wires to each cell group (you wouldn't want to charge thru the balance wires unless it is a slow charge). Then you connect the charger to the first group's + and - wires, charge it to full, then disconnect the charger and move it to the next group, etc., until all of them are full. Then there's no balancing needed because they've all been filled up the same by the same charger.
If the charger is capable of charging more than one cell group at a time, then you would follow the instructions in it's manual for hooking it up to multiple cells...but if it's a hobby charger, then it is going to do exactly the same thing the BMS does for balancing--drain high cells thru resistors, and make a lot of heat. If it has less balancing current ability, then it will be slower at this process than the BMS would (but wouldn't get as hot).
So...it depends on what you have, and what you want it to do, whether you are better off doing things with the BMS or the hobby charger.
It sounds like the BMS is probably better, not knowing anything about your other charger. If you use it, you need to connect your charger to the BMSs' charging port, and not directly to the cells, and then leave the BMS balance wires connected to the cell groups. That way the BMS can protect the cells for you, which is why it is on there in the first place.
