My boat seems to have some electrical issues I can't figure out. My alternator is putting out 12.5ish volts checked with a meter. I've roasted a new starter solenoid and melted the negative battery post on a brand new battery Sunday. Last night I replaced.the battery and solenoid and got it cranked. It was still dragging and not turning over easy. How does the battery receive voltage off the alternator to keep it charged? While it was running I removed the negative cable and the motor died instantly. That means theres no voltage returning to the battery correct...??