Can you run solar while underway?

New solar install, first long cruise with it. Running the engine with the solar connected (I have a shut off switch for the solar) it appears to be interfering somehow with the Balmar alternator and Balmar regulator. When the batteries get full the alternator charge light seems to come on. When that first happened I switched off the panels and the light turned off.

So should I not run the engine with the panels putting out juice? Is the regulator sensing an overcharge maybe?

I have had no issues for 3 years leaving solar hooked up all the time.


Usually it's only my 2-100 watt panels on a PWM controller...maybe that setup it's OK....cant say for every setup.

My panels are always on. No downside that I can see.

There is no problem with running the engine with the solar panels functioning. But to address your alternator light problem:


I think what is happening is that the alternator switches to float mode which drops its output voltage to 13.5 or so, but the solar panel may be putting out more, say 14+ and that voltage difference feeds back into the alternator charge light. Is the light very dim which I would expect if this theory is correct.


David

djmarchand said:

There is no problem with running the engine with the solar panels functioning. But to address your alternator light problem:


I think what is happening is that the alternator switches to float mode which drops its output voltage to 13.5 or so, but the solar panel may be putting out more, say 14+ and that voltage difference feeds back into the alternator charge light. Is the light very dim which I would expect if this theory is correct.


David

Click to expand...

What you describe seems to be what’s happening. The light was off and voltage was at about 13.8. Then I turned on the panels and the voltage jumped to 14.1 and the light came on.

I was having an alternator belt issue earlier (slipping) so this little red light has me paranoid now. So it shouldn’t hurt anything to run the solar?

I also see no problem with having your solar on while cruising. In my case, with the solar running - once the batteries get totally topped off, the alternators shut down which also turns off my tach signals! Not really a problem, but I prefer the tachs to be on. So I turn off my panels (via a small battery switch installed just for this purpose) and sometimes have to switch back and forth between which bank is powering the boat to keep one or both alternators from shutting off. Again, its not technically a problem, more of a nuisance/personal preference type of thing.


Ken

cardude01 said:

What you describe seems to be what’s happening. The light was off and voltage was at about 13.8. Then I turned on the panels and the voltage jumped to 14.1 and the light came on.

I was having an alternator belt issue earlier (slipping) so this little red light has me paranoid now. So it shouldn’t hurt anything to run the solar?

Click to expand...

It definitely wont hurt anything.


Ken

I agree it definitely won't hurt anything. Here is what happens when two or more charging devices are connected to the same battery:


As the batteries get full, the charging device with the lowest float voltage setting, even a tenth of a volt lower will switch to float, reduce its voltage to the mid 13s which means it will put out very little current. In the mean time the charging source with the next lowest float voltage will ultimately switch to float, etc, etc.


When the first switches to float, often the current from the second will go up. It sounds like your alternator switches to float before the solar controller which is fine. You could adjust the Balmar regulator to increase its float voltage so it is always putting out a higher voltage than your solar panels. That probably will stop the light coming on.


David