First problem - charge port sparked

Hey guys.

Connected up all my electronics (without VESC) went to plug in the charger and had a massive spark. And the light on the charger started flashing red, so quickly disconnected and this was the result. See picture.

So my questions are: Would that of damaged the BMS? Based on the charger plug is the charger fried as well? And, not being an expert but my guess is I had the charge port wired the wrong way round?

Your help would be appreciated


FYI. I did plug the chargers into the port with the charger already connected to the mains? Should I of plugged into the port first then plug the charger into the mains?

That probably. And no, it doesn’t matter which end you plug in first.

So i should be good to go if require polarity on the port?

The charger seems to be untouched. Just have to rewire.

Always connect the charger to the charge port before plugging the charger in.

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Did you check polarity of charger/charge port before connecting to BMS?

When I do it like that it always sparks, when connecting the main power first it never sparks.


What is the reason?

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I too wanna know the answer to this.

better to make the connection while the charger is not energized.

I never get sparks connecting the charge port first

Depends on your BMS…My BMS the charge port is always live so if I plug in my charger to port first I get a big arc. Guess how I found that out :slight_smile:


Hey Rich, yes I did, I posted the results on my build feed (Little Bro Trampa build) Negative on the outside L shaped pin and the positive to the other outside pin with the middle pin unused.

Shall I try again but connect the charger to the mains last?

Oh and maybe you are on to something as it sparked when plugging into port, and soaked again when unplugging from port whilst charger still plugged into mains

There’s your problem. If you followed the illustration above, it was wired in reverse. The middle tab will need to be positive(+). Unfortunately, you probably fried your charger. :disappointed: We had a couple 8s batteries we accidentally had reversed and the chargers did not work afterwards.

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You always need to verify with your multimeter!!!


The red light was still flashing on the charger after I disconnected from the port. Do you think it’s fried?

Will rewire and see what happens.

Yes I did this and got confirmation from guys on my build feed, so that’s why I was confused as to why it sparked

But the middle tab on the diagram is positive?

Verify with a multimeter…

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If you verified with a multimeter you wouldn’t be asking this question. You also should verify the plug on your charger. :thinking: