you have a charging system on that outbourd?

I would want it checked before I pluged anymore expensive electronics into the curcuit.

The manufacturer will hopefully give you an idea what went wrong.Being that it works fine untill you introduce the motor i.e charging curcuit into the loop I would suspect the charging curcuit is at fault.

just a thought.

I would also recomend staying away from crimp conectors on boat wiring and solder and heat hrink your connections.