Blew up my second BMS

ESK8 Electronics
1

Oops, bought the same cheap BMS for charge only again, connected it, attached the charger and saw sparks. A mosfet was clearly destroyed. Last time I believe the problem was connecting balance leads before ground, but this time I am not sure.

I measured voltages on the balance leads, which ranged nicely from 4.2 to 33.6v. The problem occured when I connected my magsafe connector. I use the two outer pins for negative and the inner ones for positive, I measured the voltage on the charger pins and checked for shorts on the plug and there does not seem to be any problem. When I first connected the connector, the charger LED did not change to red (indicating it’s charging). Not sure why, but when I connected the magsafe the other way around, sparks appeared.

The BMS is not expensive but this is the last step for my build and it is getting frustrating. Did I make a mistake? Should I invest in a more expensive BMS? Or should I ditch the fancy magsafe?

The BMS:

The way I connected it:

I actually did not use the balance negative but the main lead to connect to B-

1 Like
2

Anybody have any idea?

3

Bump! My lipo casing was not made to be easily opened, I would really like to include a BMS in my setup!

4

Was there any resolution to this? I purchased this BMS for charge only as well, and I also do not see my charger indicator change to charging. I have connected mine the same exact way.

My old BMS was also connected the same way and it worked great. I should have bought that same one lol

5

Bms A does not need to have the same wiring like bms B. You always need to check the wiring diagram from the producer

6

Yes it’s working fine now! I think the problem I had was the order of connecting the wires. Don’t know it by head, but tutorials generally mention this order.