Relay to disable solar when engine running

[BruceS]

Back to your original question.
Look up Gigavac.
GX14BA or GX14BC or what suits your setup. The pos sign towards your solar.
Proven on a lot of RV vehicles.

[Bulldorum]

I found a very simple and low cost solution to the exact same problem I had. A simple on/off switch between the solar controller and battery bank solved the problem. Turning the switch off prior to engine start and turning it back on again after shutdown solved the problem. I added switch movement to my engine operation flow.

[captstu]

Both solar and alternator may be damaged when run open circuit. Leave them alone. Charge to 14.5 or .4, no real difference.

[BruceS]

Be careful having the switch between the solar controller & the battery ..... a lot of controllers need to detect & set the (nom) voltage before connecting solar. Many controllers are 12/24/49 v DC now.

[sailingabe41ds]

I put my switch between the panel and the controller not the controller and the batteries. Most of the time i leave it alone in the off position. I only turn my panels on when at anchorage or longer trips when the engine is off.
abe

[KP44]

I use a breaker on my breaker panel to connect solar power to my battery bank. I just shut off the breaker when I run the engine.
I have a Balmar controller with a 150 amp generator from Ample Power for my house bank.

[hlev00]

Originally Posted by lmxr

In case of mechanical relays, the higher voltage will cause more sparking than designed and as such will cause the relay to wear out far faster. In case of solid-state relays, it is not unlikely that it will short out.

Have you considered doing something with the VE.Direct communication port on the Victron MPPTs? Victron has cables that allow to switch them on and off easily.

Great idea. Thanks!

[Dymaxion]

I asked the same question of my supplier, Renogy, and was told their solar controller adapted automatically to secondary charging from alternator without any modification or worry. No switches etc required. Every solar controller I've had also stated to "connect to battery before panel", so if you did want/want to interrupt current flow from the solar side then it seems cutting off the panel is the way to go.

[planetminder]

Originally Posted by Redline452

For what it's worth, I recently tracked down a voltage drop on our house bank and discovered that the main battery switch was the cause - over half a volt at 10A. Not having been switched off in several years, it cleaned up after being cycled on-off several times. It was the T-handle type that turns 360 degrees, "on" horizontal and "off" when vertical. Did not see that coming. Exercised all the other switches and breakers as well.

This. I just discovered the same issue with my 45 year-old battery selector switch. The starter wasn't cranking fast enough after sitting for 6 months because of the resistance through the switch. I re-routed the starter cable direct to the battery (eliminating about 8ft of cable) and the engine starts *much* quicker now. I think routing the starter and alternator through the selector switch is a bad design. Next I will do the alternator. The voltage drop through the switch must be affecting the charge sensing on the regulator for charging. (Replacing the switch of course would work, but it's integral to the panel and not readily available).
(sorry for being a bit off topic).
David

[FlyingScot]

You want to turn off the free source of power and burn more diesel and wear our belts faster? Crazy talk. Let the solar charge and if the alternator puts out less, great!

Otherwise what exact issue are you having?

[svfinlandia]

Originally Posted by hlev00

I want to disable my solar when my engine is running to avoid the solar voltage targets from conflicting with the alternator targets. If both are running the solar seems to confuse the Balmar gear. If I am running the engine, the alternator (Balmar 100A + ARS-5 regulator) can supply plenty of charging current compared to my solar (2X 190W banks each with a Victron 75/15 MPPT controller). Some suggestions are to set the solar target voltages below the engine alternator targets but then the solar never gets the batteries (Trojan T125) to their proper voltages.

So I am thinking of using two relays (one for each solar bank) so that when the engine is running the solar is disabled, but as soon as I shut down the engine, the solar will do what it can. I would use the relay to disrupt the current coming from the panels to the MPPT controllers. Automotive relays are designed around 12V @ 40A (480W) which is a lot more than either solar bank can supply. Is it okay if the solar voltages are higher as long as the total Watts are less than 480W?

Thanks,
Harry

A simple toggle switch works fine for me. I always turn off the solar when the engine is running or when I am plugged into shore power.

Al, S/V Finlandia

[goboatingnow]

Again disconnecting the solar is fixing a problem you should’ve be having in the first place. There’s no issue ( and it’s best practice ) to have all charge sources on at the same time , Ive had my battery charger , alternator and PV all connected at the same time

If you have a voltage measurement issue that will not be fixed by turning off the solar.

[billcrowley]

I installed 180 watts of solar on our Newport 30-2 six years ago, and never considered such a conflict with alternator output when the auxiliary was running. The system has been operating just fine all this time.

[flightlead404]

I have just discovered a problem with my new solar installation and my existing shore power charger. This problem could just as well exist with any two charging mechanisms (I think, still researching).

It appears that the solar controller charges at a high enough voltage to cause my shore power battery charger to think there is a fault/over voltage situation and to go into a failure state. To recover I have to shut off all power, DC, shore power, and solar, then restart the charger. It does not recover automatically.

I believe this could happen with any two systems where one chargers at a higher voltage than the other and where the lower voltage mechanism has a high voltage fault sensing mechanism.

[MJH]

Originally Posted by hlev00

I want to disable my solar when my engine is running to avoid the solar voltage targets from conflicting with the alternator targets. If both are running the solar seems to confuse the Balmar gear. If I am running the engine, the alternator (Balmar 100A + ARS-5 regulator) can supply plenty of charging current compared to my solar (2X 190W banks each with a Victron 75/15 MPPT controller). Some suggestions are to set the solar target voltages below the engine alternator targets but then the solar never gets the batteries (Trojan T125) to their proper voltages.

So I am thinking of using two relays (one for each solar bank) so that when the engine is running the solar is disabled, but as soon as I shut down the engine, the solar will do what it can. I would use the relay to disrupt the current coming from the panels to the MPPT controllers. Automotive relays are designed around 12V @ 40A (480W) which is a lot more than either solar bank can supply. Is it okay if the solar voltages are higher as long as the total Watts are less than 480W?

Thanks, Harry

This is the first I have ever heard of a possible problem with them both being connected at the same time. I have had my 4x140 (560W) solar panels continuously connected for six years and have not seen any problem. Further, there was no mention or warning on the installation instructions or in any conversation with the manufacturers.

I think you are making the situation more complicated than it is. If you are still concerned I suggest you call Balmar and present your issue and see what they say. I have talked to their technical guys many times and they are very helpful.

~ ~ _/) ~ ~ MJH