Battery surge when plugging charger in (destroying the connector)

Hey everyone,

I’m hoping some of you pros can help me here.

About a week ago I plugged my charger into my board while it was standing against the wall. Obviously, with my luck, the board fell over and the charging port (gx12-3pin) sheered right off (on the charger side, the board connector is fine)

So I hit up Amazon and purchased a new connector for the charger.

I then proceeded to solder on the gs12 connector, making sure the positive and negative cables went to the right pins. This was double, and triple checked by a mutlimeter.

As soon as I plugged in the charger (charger was not in plugged into an AC outlet) a surge from the battery went back to the charger and blew the pin out of the connector.

I assumed I shorted something so I re-did the job again this time making extra sure I had no shorts.

I even opened up the charger, and used a volt meter to check continuity directly from the PCB allll the way back to the xt30 connector where the battery plugs in. No shorts of anykind were found and continuity all the way through is good!

Plugged the battery into the xt30, and the same thing happened again!

I’m pretty sure all the wiring is good, I mean there’s really no errors to be made it’s a simple red and black wire going into the gx12.

So my question is, could the charger or bms have been damaged when the board fell?

Is there something else I should be looking at?

Thanks everyone!

PS- This is a stock BKB DUO.


what volts from the charger and what from the charge port?

lol if you want to solder it up again quick then take a video of it blowing up wires when connectors that would help.

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Haha! Everyone loves seeing a good fireworks show!

So when I put the voltmeter on the charge port, I get 36v.

When I put the voltmeter on the charger I get 42v (oops before I said I got zero but I was wrong)

When I do put it together for the 3rd time, I’ll try to get a video of it as well as all the continuity checks


Well, just as an update incase anyone else ever has this problem…

I opened up the charger and it turns out the red wire was going to the negative pcb point, and the black wire was going to the positive! The stock charger was wired in reverse…ugh!

So when I wired the gx12 I actually needed to wire it backwards to fix the issue. Crazy!

Always check those chargers, you never know how those chinese chargers are wired!

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Always have the charger plugged into the wall before you plug it into your board.

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