Interesting to read about the various battery/inverter hookups. Well, here is my set up and what I do to operate the system. My battery compartment contains three 12 volt Exide Deep Cycle Batteries. Two of the batteries are hooked in parallel (+to+) (-to-) and these two are totally isolated
to to the refrigerator inverter. Nothing is hooked to them but the inverter. The inverter I'm using has an orange on/off button and a digital readout. When we are ready to travel and unplug the shore power, I turn on the inverter, which allows the refrigerator to keep running. When plugged in to shore power, these two batteries are NOT charged. I currently carry a portable 10A battery charger that I hook up when we park and hookup to shore power. I have future plans to install an onboard single bank 15A automatic charger that hooks into a 110v. power supply and then when shore power is connected, the charger will automatically charge up and maintain the two batteries.
We've travelled up to 6 hours so far and the inverter does a fine job of supplying 110v. to the refrigerator and the temps in the fridge are 35 F and -4 below in the freezer. The 3rd battery in the compartment is the usual coach battery charged by shore power and operates the 12v. accessories.