Re: Overcharging 18 volts
It's hard to say without checking with a meter. When you put the wires together, you are shorting the the ignition system to ground and disabling the ignition system. That's exactly what the "Kill Switch" does. If the motor runs with the two wires apart, and you can turn the motor off with the key, then your ignition switch is probably OK.
Again, you need to check the Kill switch with a meter. No getting around it. If your Kill switch has a lanyard with a little plastic clippy thing, you need to install the plastic clip and check the contacts/wires with a meter. If you read an "open" circuit, use those contacts. When you remove the plastic clip, you should then read a short on the same wires. When you remove the plastic clip with the motor running, it'll kill the motor.
The original purpose of the Kill Switch with the lanyard was a safety feature. You connect the plastic clip to the switch, and the other end to your belt or somewhere on your body. If for some reason you get thrown overboard, the lanyard connected to your body will pull the plastic clip off of the switch, thus killing the motor. Otherwise the motor will keep running and maybe run over you or just keep going leaving you stranded in the water.
If you read a "short" with the plastic clip installed, then that's just like putting the wires together and it won't work. Don't use that set of contacts/wires.
