At first when I saw the promariner I saw right where 180$ could be saved.
Then I remembered how on my particular vehicle that for some unknown reason, the engine computer will cut back the voltage to 13.7 well before the house batteries are back above 80%.
I now have installed 2 small voltmeters on my dashboard, one on the house and one for the engine battery, and they have been enlightening.
Even at a steady highway rpm of ~2000, I can watch the voltage fluctuate between 13.7 and 14.8. My voltage regulator is in the engine computer.
I still wouldn't pay 180 dollars to keep the voltage steady.
I use manual switches. I now have three of the Blue seas Mini series.
One for the Ignition, one for the loads, and one for the solar. But of course setting any of the 3 switches to 'both', parallels the batteries.
In the OP's situation, I like the idea of another toggle switch and perhaps a beefier solenoid/contactor. Perhaps instead of taking juice from the engine battery, hook the lead from the engine battery side of the solenoid, directly to alternator(+) stud.
Isolators with finned heat sinks are to be avoided in my opinion. Heat sinks mean wasted energy.
I like the Blue seas ACR's for simplicity and durability. If i were to start over, it would be with one of those.
