I need help connecting my BMS to the packs.
Nothing is color coded or marked on the BMS
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Not sure if the exact pin out in your battery, but 3 & 4 will need to connect to 5.
You’ll need to find out exactly how your battery balance wires are cabled to do it properly
He should be able to measure the pins from the battery with a multimeter to determine which cell is which no?
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Where did you get the packs? Bought at the same same time?
Exactly my thoughts.
1)first you have to find out if your batteries use same cells and if they have about same usage on them. if one battery is much older or has different cells, you will destroy your bms quickly. if cells are same and same age, continue
2)take first battery (X), take you multimeter and check voltages on balance wires. stick multimeter probe in connector in A and another probe in B. hold first probe in A and move second probe to C, then to D and so on up to G. check voltage of whole pack. for example, if your pack gives output of 25.2V (full battery), voltage between balance wires should increase for 4.2V (A to B 4.2V, A to C 8.4V, A to D 12.6V…). if your voltages are not same between each group, you should get 6S balance charger and balance battery.
3)repeat whole 2) process for another pack (Y)
4)connect main positive wire (red) from pack X to main negative wire (black) on pack Y (fat purple line drawn on photo). Use thick wire because all the current will pass through it.
Check voltage from negative (black) wire on pack X to positive (red) wire on pack Y. if your batteries were full, voltage should be 50.4v or very close to it -> voltage of pack X + voltage of pack Y.
5)unplug bms balance connectors (they are physically two pieces, but I will consider them one piece)
6)now when your packs are balanced and you are 100% sure that order of your balance wires is correct, connect them with bms balance wires in this order:
1 - A
2 - B
3 - C
4 - D
5 - E
6 - F
7 - G and H - last wire (G) in X pack has to be connected to first wire (H) in Y pack, and they are together connected with wire 7 in bms
8 - I
9 - J
10 - K
11 - L
12 - M
13 - N
Do not connect balance connector in bms yet!
7)check voltages on bms balance connector same way you did with battery packs. first probe in 1, second in 2. hold first probe in 1, move second probe to 3, 4, 5… each measurement should increase voltage for 4.2V, up to 50.4V
8)connect your new 12s packs main negative (black wire from X block) to B- plate on bms
9)connect balance connector to bms
10)wire bms as you wish and you are done!
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