Do turn your solar off while motoring?

[masonc]

If by "turn off solar" you mean turn off battery connection to controller, don't do it. The open circuit PV voltage can damage some controllers. Just leave it connected, it will go into float mode.

[Lifeonalean]

Originally Posted by masonc

If by "turn off solar" you mean turn off battery connection to controller, don't do it. The open circuit PV voltage can damage some controllers. Just leave it connected, it will go into float mode.

In my original post I talked about a switch between the panels and the controllers. My question came about because I get a “Battery overvoltage” warning when I run my engine now, right after installing the panels. It went up to 16 volts before I shut it down. Everything works fine when on shorepower though. Bad alternator? Just a coincidence? Alternator is a Delco Remy 94amp unit with internal regulator.

[john61ct]

Start with the VR. Actually DMM check is first thing

[masonc]

Originally Posted by Lifeonalean

In my original post I talked about a switch between the panels and the controllers. My question came about because I get a “Battery overvoltage” warning when I run my engine now, right after installing the panels. It went up to 16 volts before I shut it down. Everything works fine when on shorepower though. Bad alternator? Just a coincidence? Alternator is a Delco Remy 94amp unit with internal regulator.

You should change to an external regulator. I'll bet turning off the PV does not stop the 16v overvoltage but you can test that quickly. I had a problem where the regulator sense wire broke while underway, alternator put ot 16.75v until I disconnected the field wire.
I'l bet your regulator is shot.
Don't touch your PV, it's not the issue.

[Singularity]

Originally Posted by masonc

You should change to an external regulator. I'll bet turning off the PV does not stop the 16v overvoltage but you can test that quickly. I had a problem where the regulator sense wire broke while underway, alternator put ot 16.75v until I disconnected the field wire.
I'l bet your regulator is shot.
Don't touch your PV, it's not the issue.

I'd touch/review/RTFM on everything on the charging side of the system. A good mechanic is not a broken parts exchanger but instead is a good diagnostician, unless he wants to replace even more parts. I understand that MPPTs are typically reliable, not absolutely reliable. We have a situation here where a change on the charging side appears to be immediately associated with an alternator voltage regulator failure.

Maybe the alternator VR was having problems prior to this and we only discovered the problem after doing solar work (observation bias?).

Maybe the forces of the universe intended for the alternator VR to die on its own same time doing the solar work (natural death for the VR?).

But if something in the entire charging system was messed with in a manner that killed an innocent alternator VR, replacing the alternator/VR (particularly with a more expensive system than is otherwise required) isn't necessarily the lest expensive correct answer. It's prudent to recheck everything.

[Lifeonalean]

((UPDATE))
Thanks guys for all your help! it was indeed the alternator regulator causing the overvoltage. It is an automotive style Delco remy with internal regulator. I decided to upgrade to The Balmar high output alternator with the mc-614 external regulator and now it works like a charm! Looks like the old alternator fried my batteries As a backup, I installed a switch so in case of an external regulator failure I can switch to the new alternators internal regulator. All in all I feel pretty good about the upgrade. Thanks!

[john61ct]

Great decision and result

[hellosailor]

"Automotive" and boat nominal "12" volt equipment is usually designed to run at 13.8 volts with an expected range from 14.4 volts, which is the maximum for normal alternators, down to about 12 volts, which is a weak battery. At 16 volts you start with every light bulb in the systems blowing out early, followed by all the electronics blowing out, since they are not designed to run at 16 volts. 15, they might tolerate. 17 and you'll see multiple failures in a hurry.

So whether your regulator is internal to the alternator, or external, it needs to be tested and repaired or replaced.

That's problem number one. Problem #2 is that there is no "One ring to rile them all." Your regulator/alternator should have a voltage sense lead, which normally goes to the battery bank(s) positive terminal to measure the actual charging voltage at the battery. When you have multiple voltage sources (alternator+solar) then you have two sources which may be fighting each other. Ideally you would adjust the charging voltage from both of them, so that when the alternator is charging, let's say it puts out 13.9 volts, and when the solar is charging, it puts out 13.8 volts. That way the solar will shut itself down while the alternator is running. You can set it up either way, to put one or the other to sleep, and the exact voltage will vary with your chargers and batteries, but a good "dealer" would make some similar accommodation and not confuse things with a manual switch.
In practice, the two charging sources are probably doing this anyway--you just don't know what's up unless YOU have them set up the way you prefer.

[Compass790]

Thanks for update. Bummer you fried yr batteries. What sort of batteries? I would have thought FLA's would have handled 16v for a brief period. Well actually I know they do as our 225amp deepcycle Crowns did when our VR failed but it didnt go unnoticed for long as we have a voltmeter on cockpit panel.
Good idea about switch between 2 VR's, was considering doing the same.
Sounds like a nice upgrade anyway.

[Lifeonalean]

Originally Posted by Compass790

Thanks for update. Bummer you fried yr batteries. What sort of batteries? I would have thought FLA's would have handled 16v for a brief period. Well actually I know they do as our 225amp deepcycle Crowns did when our VR failed but it didnt go unnoticed for long as we have a voltmeter on cockpit panel.
Good idea about switch between 2 VR's, was considering doing the same.
Sounds like a nice upgrade anyway.

They were “Vision” 200 ah Gel batteries. They were 10 years old so I think this was the final nail in the coffin for them

[Compass790]

Oh well Gels are a lot more voltage sensitive. Look on the bright side, at least you'd had 10 years outa them, wuda been a lot more painful if VR had failed on new gels.

[NYSail]

Hello all..... so I am a complete novice with solar let alone marine electrical...... that being said if the mppt controller is reading 16 v what is happening is the controller is sensing the total voltage of batteries and not just what the solar is putting out. And assuming controller is working properly solar is not feeding the batteries and thus it’s reading what alt is putting out. So if that’s the case he can unhook solar and then watch the volt meter on the electrical panel and it will show 16v confirming what you all are saying..... bad regulator. I know this is kindergarten stuff but just want to better my knowledge.

Thanks for your patients.

Greg

[Ambler]

Originally Posted by Triumphant

My alternator is regulated at 14.0 Volts, my solars (350 watts) are regulated at 14.8 Volts so if I have both on when motoring the alternator shuts off as it thinks the voltage has been reached. I discovered this when the red light came on (thought the fan belt had gone) whilst motoring and I found the alternator was very cold and producing no amps, turned off the solar and things went back to normal.

I need the larger amount of amps from the alternator to top up my batteries so yes I turn the solars off when motoring otherwise I end up with undercharged batteries

Same problem. I have my solar panels connected via a MPPT controller to my house battery bank and my engine alternator connected to my engine start battery. I have a voltage (dual) sensing relay which connects both batteries when either battery is being charged.
My engine alternator light and buzzer comes on when the batteries are at a higher voltage because of the solar set point than the engine regulators.
Will this situation damage my alternator? Does it effectively disconnect the field wire when the alarm is on?
I have been disconnecting the panels to cancel the alarm as the OP has said.
What about disconnecting the VSR somehow when motoring on a sunny day?