Port battery over voltage

[All's Well]

Had a series of alarms today
Port gage showed voltage at 16.9V idling, 17.6V @ 1100RPM (compared to 13.8V for STBD)
when the engine is off I show port @ 12.5V & Stbd @12.4

Is this simply an alternator giving up?

 

[fr8dog]

Yes, sounds like the alternator. Happened to my stbd. then two weeks later the port.

 

[Bt Doctur]

avoid running that motor with a runaway alt, you will damage the electronics. Should you need to run the motor , disconnect the alt wires first

 

[All's Well]

Great - Thanks
I'll pick one up this week

 

[All's Well]

Alternator it was - "Notherdecision" a fellow forum member loaned me his spare and I replaced this weekend.
All's Well now

One other note - If you're going to do this on a boat with 6cta's you might as well replace thermostats as the housing is directly behind the alternator and makes their replacement a non event. Remember 2 thermostats per engine