Solar install on dual battery setup

[allyncooper]

I have a 125 ampH second battery installed in the truck charged with by the alternator and usiong a Keyline In-Pro 140 Isolator which works fine. I have a small Dometic fridge ( 5.5 amps 66 watts) and other small intermittent loads on the battery. I want to add a 100w solar panel with MPPT controller to "top off" the battery if the truck is not being driven for a few days and not being charged by the truck alternator. Question is how do I properly wire given there would be two charging sources, one being the truck alternator and the other from the solar charge controller? I assume the solar charge controller will regulate this as will the isolator (in other words both controllers will not permit an overcharge), but wanted to ask advice from those with similar setups if there is anything extra I should be installing for this type of setup? TIA

 

[Joe917]

Nothing extra needed. Connect the solar controller to the house battery side. PMW is fine for 100w. I would consider adding a battery monitor( voltage alone is not a reliable indicator of charge). Trimetric recommended.

 

[DiploStrat]

Just to be REALLY pedantic - the smart isolator does not regulate the charge - all it does is connect the second battery to the starter battery whenever the voltage of either battery exceeds a set point (usually about 13.2v) and disconnect the two when either drops to another set point, usually about 12.7v. And this is exactly what you want with a flooded or AGM lead acid battery. This means that when your camper battery is on charge from your solar set up, the relay will close and charge the starter battery as well. Which is also what you want.

The charge performance of your alternator is determined by the voltage regulator in your vehicle.

All of this is another way of saying that Joe917 is exactly correct.

 

[dwh]

This means that when your camper battery is on charge from your solar set up, the relay will close and charge the starter battery as well...

...IF the relay is dual-sensing.


(Your pedantry is slipping, Fred. )

 

[DiploStrat]

True. And to put the angels on the head of the pin, even a single sensing relay is dual sensing when combined.

I am only aware of one single sensing intelligent relay, the one made by REDARC. Doesn't mean that they aren't out there, but dual sensing makes more sense to me.

 

[allyncooper]

Thx for all the replies. Good to hear I don't have to do anything special for this setup.