Spark when connect ESC

[Serum]

It's completely normal;

The internal resistance of the capacitors is ~0 ohm when they are 0V, that's why they spark.

To protect the plugs, you can simple add an extra small 2mm plug to the + pole. First you hook up the - pole, than the small 2mm plug, which gets the punishment, then the big high current plug. You can also simple replace the plugs every now and then.