General mechanic question

[evensteven]

I know its not v8 but there is alot of knowledge floating around this forum.

I have a ski boat with a chevy one wire alternator on it, it went out and i replaced it with a regular 3 wire alternator, I'm cheap, I ran I wire from the pos side of the coil to energize the field coil to start the charging. now it charges at 15 to 16 volts, this is a death sentence to the battery. Why is it doing this? bad alternator?

an idea; the coil is fed slightly lower voltage, ballast restitor, will this make the alt think the voltage is low on the system and over compensate by putting out over 14.2 v's? Any advice is helpful.