Bms charging issues

Ok guys I need some help to determine why my bms is charging so slow. This is going to be a pain to read but please bear with it. I’ll start by listing my setup. Batteries: 4x turnigy 5000mah 25c 3s in series Bms: 80amp bestech bms Vesc: Hglrc 50a vesc Motor: Turnigy aerodrive 6374 149kv A while ago, before I had everything mounted in an enclosure, I tested my setup to see if it would charge, which it did. (Started @3.7volts per cell all the way to 4.2 per) After that, I rewired my bms with 10awg wire instead of 12, and in the process accidentally wired my charger port backwards(idiot alert). Without knowing that, I plugged in my charger and heard a pop from the bms and saw some magic blue smoke, and tried to unplug it as fast as I could, but it still did a lot of damage. I then switched the poles of the charger and waited to see if it would charge. I checked the balance wires of each battery every hour and they were slowly going up. (Like .05v per cell/hr.) Very slow but at least it still charges. I then took the board for a ride and it discharged perfectly fine. What I’m saying is before I rewired the charger backwards it charged much faster. Now it’s been plugged in for almost two days and It’s only charged .3v per cell. Do any of you know what’s wrong? do any of you know someone who repairs bms? I can send pictures if you guys want. Thanks.

Pop and magic blue smoke? Sounds like you need a new BMS to me :slight_smile:

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Your BMS is probably charging slowly because you let the smoke escape. Gotta keep the smoke in.

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It’s weird though because I can still ride the board like nothing happened.

Is your BMS wired for charge only or discharge as well?

Either way, smoke = something fried

Replace the BMS and all should be fine :slight_smile:


I have my bms wired for discharge and charge