Alternator problem

[Rjbrice15]

I have a 92 stingray with a 3.0 mercruiser. The other day I was out and the analog Gauge read 11v for a good run to the other side of the lake, then spike up to 16v. I came back in and put a meter on it. It's charging at a constant 15.8v on my multimeter. This is high. Just looking for some direction on this. After reading a little I put the meter back on it today and started it up. Put the meter on AC and im getting a reading of 34.4v AC. Should I get a new alternator or is this okay? Just bought the boat 3 months ago and put it in the water last month.

 

[alldodge]

15.8V is to high, pull the ALT and take it to the local auto store and have them check it. Using the AC side on a DC circuit will nt provide a good reading, that said I think you have one side of the diode pack which has burned out

 

[bruceb58]

Yep, as alldodge said, one or more of your diode triad has gone south hence the high AC reading. It should be close to 0V AC.

 

[Rjbrice15]

Thanks guys. We have a local electric shop that does marine alternators. I called him this morning and will be taking it to him later. Thanks again