Bang! Black Fingers! That was scary!

I have traced every wire as well as connections and everything is correct.

Seems like if the voltage is far enough off you could still have an inrush but it does seem like an excessively large spark, I was getting bad sparks (frying xt-90s) with hooking up a 12S to a VESC just from the inrush current into the capacitors, an antispark plug has completely eliminated the problem for me (also using 10S now). In this case the antispark would also help to reduce the chance of dumping a large amount of energy from one battery to another since the resistor in the antispark will help to “regulate” the current flow (assuming it’s not so high it burns up the resistor too, I have done that before and is really hard to pull out the antispark plug once the resistor inflates after frying, make sure it’s fully inserted before you start drawing power through it).

i can’t wait to hear how you fixed it! =)

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It seems it fixed itself with a big ass spark. I haven’t had any other problems so far. The packs are wired in parallel and the positive leads are connected to the vesc. As soon as my BMS shows up I’ll connect the negative lead tonit and then to the vesc. I am however running an xt90 antispark going into the vesc.

someone here was using anti-electric paste to stop the spark. it woudnt reduce the current flow and protect the caps or your cells in paralllel but as the connectors come together the paste has higher resistance than air so no spark possible. cheap-man’s antispark.

spark size is directly proportional to voltage. its Paschen’s law. if a dead cell is 3.0V and a full cell is 4.2V thats a 1.2V MAXIMUM difference.

The spark in the photo was not a 1.2V spark. just sayin.

But 10s times 1.2v is a 12v spark. Not sure if the fact it’s a 2p would make a difference. However, everything is wired together and soldered and I have had zero sparks.

^^ believe it was this kind of thing that was happening to me and might have happened here. It’s not that we’re getting to the thousands of volts needed to actually jump across the air along but once the connection is made and current has started to flow as the wires come apart (maybe they bounced a little as making the connection) and the current continues to flow across the air resulting in a bright hot spark but at relatively low voltage.