Maintaining RV batteries
That looks like a good one. After 28 years on the tool route, 4 trucks with 3 using the constant duty relay, I wired only the engine start batteries to the relay and controlled it with a toggle switch. I ran the diesel in the summer for a/c and heat in the winter. The interior lights stayed on most of the time so I needed a lot of current to run it all. The dual 12 volt engine start batteries got charged on the way home. No more boiling them dry.
Mine had the switch on the dash to activate the solenoid type isolator also, and my 4k Onan generator normally started off the engine battery.
I could connect the coach batteries with that switch if needed to fire the engine or generator.
The original charger/power supply was old and had some issue's and the PD system was the ticket.
I got the charge wizard external indicator, so I could look in the rear view mirror and see the indicator LED flashing it's codes and know what the charger was doing at any given time.
I also wanted to end up with solar panels on the roof but never got around to it.
Our kids would usually bring a TV and an Xbox along, so an inverter was almost always in use at night as well, without having to run the generator.
Those 4 golf cart deep cycles kicked ***, and only once did I ever need a jump to get something going to recharge and that was after dry camping for 4 days without firing the generator.
Luckily my Dad gave me the 15 foot super heavy Semi truck style cables with the RV and I had some friends close by.:D