[Mbenham13]

I recently purchased a 2008 4300 Sovran and been fighting with an electrical issue. 

Boat Details: 
2 Volvo Penta, D6 435 with IPS drives
Each Engine has 2 (yes 2 ) alternators 
Boat has 8 brand new AGM batteries - 5 house and 3 engine

To Summarize: 
when I run at higher than idle RPM's I often get an error that shows up on my Prosine inverter display saying over voltage or over charging of Prosine battery and attempts to restart. The analog voltmeter on the DC system panel shows house voltage often off scale at greater than 16 volts. 

I found that if I disconnect the starboard alternator( call it the inboard alternator) on the port engine the over voltage alarm does not occur, just to be sure I did an A-B-A test and disconnected the port alternator (outboard alternator) on port engine the alarm still happens. I then ran the boat for a few hrs with the inboard alternator disconnected and all was well for a bit but then I started noticing the digital voltage readout on the multifunction Volvo Penta displays at the helm started showing erratic voltages for the port side with values typically ranging 16-18 volts and quite noisy. The starboard voltages were flat lined at 14.2 volts. 

I have tried to clean up all the contact points on the inboard alternator but to no avail, it is still happening. 

Do I just need a new alternator ore is there a different potential cause? 

Regards
Mbenham13

[Misdirection]

Did this problem start with the new batteries? A bad battery can cause strange issues....I'd recommend having them tested.

With that said, it sounds like a bad voltage regulator. Unfortunately, I believe those are internal on the alternator on a D6, meaning you'll likelt need to replace it.

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[Mbenham13]

I cant say for sure that the problem started with the new batteries as they were past due and causing other issues prior to changing them. Took boat out for a cruise today and as long as the engine rpm did not exceed 800 everything worked well but at 850 RPM the voltage started getting above 16 v and the inverter started alarming and displaying " Prosine warning: Chg Hi Bat V -W" and voltage reading was off scale on analog meter on DC control panel.

Do you know why I have 4 alternators - the manual indicates I should have 3?

Also one other question - Is there any recommendation about when if ever I should turn the Inverter Circuit breaker to off.

Thanks

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Oh and by the way - I had my Ports and Starboards mixed up in original Post. The offending alternator is definitely on the Port side of the Starboard Engine. If that matters at all.

[Misdirection]

The alternator is not charing until you get to 850 rpm, so that makes sense why it isn't reading above until then. You can always take if off and take it to napa and have ir tested.

No idea on why you would have four alternators, you can always email Tiara customer support, include your hull id, and inquire if it came from the factory that way.

And I do not have any recommendations on when the inverter should be turned off at the breaker.

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