Battery isolator with solar panel?

[bat119]

I have a 100 Watt solar panel, 2 6 volt batteries
I am thinking about installing a battery isolator to charge the house batteries while driving from the alternator, the easiest way to do this would be to run a wire from the isolator directly to the house batteries.

Is there a danger of overcharging the house batteries?

[pconroy]

In our '16 Greyhawk, the house batteries are already connected to the alternator. They'll charge when driving. I leave my Solar MPPT charge controller connected and figure it'll see higher voltage at the battery and "disconnect", switch to Float.


I've wondered how smart alternators are. I suspect not too smart.
One thing that could be a problem is putting too much strain on the alternator. That's apparently a big problem with Lithiums: they'll accept too much current from the alternator and you risk burning it out.


Over charge the batteries?
I don't know - but AFAIK, the alternator doesn't overcharge the chassis battery.
I'm curious to know what it "sees" when the house and chassis batteries are on-line.

[bat119]

Originally Posted by pconroy

Over charge the batteries?
I don't know - but AFAIK, the alternator doesn't overcharge the chassis battery.
I'm curious to know what it "sees" when the house and chassis batteries are on-line.

I think I have it solved a smart isolator would work.

Dual Battery Smart Isolator DEWINNER - VSR - Voltage Sensitive Relay, 12V 140 Amp

VOLTAGE SENSITIVE RELAY: DEWINNER Automatic 140 Amp Dual Battery Isolator is all you need to charge Two Battery Systems. Voltage Sensitive Relay (VSR) cuts in at 13.3 volts and cuts out at 12.8 volts to ensure your primary battery is always charged and ready to start your vehicle. It's like having two separate power sources for each battery while only having one alternator!

[craigav]

Originally Posted by bat119

I think I have it solved a smart isolator would work.

Dual Battery Smart Isolator DEWINNER - VSR - Voltage Sensitive Relay, 12V 140 Amp

VOLTAGE SENSITIVE RELAY: DEWINNER Automatic 140 Amp Dual Battery Isolator is all you need to charge Two Battery Systems. Voltage Sensitive Relay (VSR) cuts in at 13.3 volts and cuts out at 12.8 volts to ensure your primary battery is always charged and ready to start your vehicle. It's like having two separate power sources for each battery while only having one alternator!

I think most, if not all Jayco Class C's already have a battery isolator relay. It is under the hood almost directly in front of the steering wheel. It is connected to the engine run switch and the emergency start switch. You could wire it for other triggers if desired, but doing that is usually not needed. ~CA

[bluztoo]

Interesting - makes sense. Going to go look for mine on my Melbourne. Doing some solar and trying to figure out what I need to change versus a whole new system.

[pconroy]

Yeah - mine has the isolator but I'm not sure how smart it is. I thought it was just a manual relay triggered by the switch.

[craigav]

Originally Posted by pconroy

Yeah - mine has the isolator but I'm not sure how smart it is. I thought it was just a manual relay triggered by the switch.

Yes, it isn't all that smart, no logic circuit, however it is wired to charge both coach and chassis batteries when the engine is running and separate the two when the engine is not running.

A common "smart" addition that many RV's already have installed is the Intellitec BIRD. This could easily be added to the relay that most of us have in our Class C if needed or desired.

https://www.amazon.com/Intellitec-00...A%3D%3D&sr=8-3

[bluztoo]

Have seen those in different brands - dc to dc isolator. But then see setups with just the relay that trips back and forth based on time and voltage. Not sure what the more expensive stuff does better. Will seek out my son the electrical engineer. Of course there's some brainiacs on here that know too. I'm learning. **Having read the small print I can see that one advantage is that it charges both directions - so when you're coach batteries are full it will spill over to the chassis battery. Nice function.

[pconroy]

Originally Posted by craigav

Yes, it isn't all that smart, no logic circuit, however it is wired to charge both coach and chassis batteries when the engine is running and separate the two when the engine is not running.

A common "smart" addition that many RV's already have installed is the Intellitec BIRD. This could easily be added to the relay that most of us have in our Class C if needed or desired.

https://www.amazon.com/Intellitec-00...A%3D%3D&sr=8-3

That is a fascinating device. A little Googling down the rabbit hole took me to this recent thread about BIRDs and alternatives to Intellitec.

https://www.winnieowners.com/forums/...rs-359719.html




One thing I saw on the Intellitec is that the voltages look old-school SLA. I know I'm not going to Lithiums anytime soon in my coach, but if I were, I might look for a BIRD that seems to be more Lithium aware.