Two questions on BMS wiring

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Conrad
Posts: 4
Joined: Thu Aug 10, 2017 3:56 am

Two questions on BMS wiring

Post by Conrad » Thu Aug 10, 2017 4:20 am

I have a BMS with no C-, so only B- and P-, which means I will have to solder both the charger - and ESC - on the P- of the BMS. Is the best solution to solder both cables to the BMS or to solder one and then have a sort of Y connection a couple of cm after (hope this is clear...)?

For the sensor wires, is there any specific order for the connection to the cells or is that just to be able to identify a defaulting one more easily?

Glider
Posts: 9
Joined: Thu Aug 03, 2017 7:09 am

Re: Two questions on BMS wiring

Post by Glider » Thu Aug 10, 2017 4:20 am

You can connect the negative charge cable either way.
The balance wires must be connected in correct cell order. If you get it wrong you may permanently damage the bms

Conrad
Posts: 4
Joined: Thu Aug 10, 2017 3:56 am

Re: Two questions on BMS wiring

Post by Conrad » Thu Aug 10, 2017 4:22 am

Ok, noted.
There are no numbers on the wires coming from the BMS. So i just need to make sure the first one is connected to the cell that is the positive side of the battery, and then move along until I arrive at the cell with the main negative wire?

Hillso
Posts: 12
Joined: Tue Aug 01, 2017 1:27 pm

Re: Two questions on BMS wiring

Post by Hillso » Thu Aug 10, 2017 4:23 am

Glider wrote:
Thu Aug 10, 2017 4:20 am
You can connect the negative charge cable either way.
The balance wires must be connected in correct cell order. If you get it wrong you may permanently damage the bms
WILL permanenlty damage the BMS. You'll have all that wiring done, and you'll plug it up and see that nothing sparked and it will seem fine. Meanwhile the traces are heating up rapidly and as soon as you pick up the BMS (provided its heat shrinked) one or two resistors will melt off and stick to the heatshrink and if you're lucky you won't burn traces, but the board will be useless until the resistors are replaced or re-flowed. And most times that doesn't even fix it because something else burned up and didn't do it in an obvious way.

i have a bin of dead BMSs that i killed this way.

check your voltages on each balance lead to assure they are indeed sequential BEFORE plugging in the BMS. Do that 100% of the time and you will catch and fix errors before you cook off balance resistors.

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