Building my 24V 150AH Battery, am I on the right track here?
- Thread starter Jad Oolo
- Start date
MisterSandals
Participation Medalist
So there are 12x 50Ah cells configured as 3P4S?
So this is where I'm at. Charging both batteries with 13.8V and 5A. I'll connect the 2 packs in series and attach the 24V 8S BMS. I'm wondering at what point I should stop charging as far as milliamps and if I should use the BMS leads that are on the packs or solder new ones to the bus bars?
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Yes. I was a bit disappointed, but its what I have now and should be fine
MisterSandals
Participation Medalist
Are you bypassing the BMS to charge?
If so, YOU are the BMS and need to monitor individual cell voltages. Once one cell gets over 3.45V the voltage to increase at a much faster rate. To properly top balance, you would want to charge in parallel or one cell at a time.
I keep checking the balance leads and set the voltage. As it gets closer I'll monitor more closely, but the volts should stay the same and the amp should start to drop as the cells absorb. Hopefully this is right. I did not want to tear these batteries down any farther to set in parallel. Thats way above my knowledge LOL
If I get these 2 batteries close enough to full SOC to put them in series and hook up the new BMS, I was hoping the balancer would look after the rest. Each of the 3 cells in parallel have now become one cell for me, which is an issue for me now. I'll never know exactly how each pouch is performing.
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MisterSandals
Participation Medalist
It will pull 25W so it may get hot. But it will work, just don't let it overheat.
25W / 3.45V = 7.25A
Why wouldn’t you leave the original BMS in place? Why risk destroying the cells with imbalance or overcharge? It makes no sense! You ALREADY HAVE A PAIR OF 13.8V BMS sitting there…
Do this instead… set your power supply to 3.55V and directly charge each of the stragglers up to 3.45V it should be faster that way.
I'll deffinately do that. Way quicker for sure. I wanted to visualize the batteries in the space they will be living and had to remove the bms's to get the batteries apart. In hindsight, I should have just put them back on. I have both packs nearly perfect now at 3.450V/cell. 2 cells to go.
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