As the owner of a camper with a 12-volt refrigerator, I can tell you that my fridge consumes about 4.5 amps. For the eight hours that my solar panels are not able to generate any energy, that's 36 amp-hours. On top of that, the camper has parasitic energy consumption due to the propane detector, radio memory/clock and thermostat. All told, my camper can consume 40+ amp-hours between dusk and dawn.
If the propane furnace is used during the night, my camper can easily consume 60 amp-hours during the night.
BTW, the original poster referenced a WFCO inverter when he/she actually was referring to the onboard converter/charger.
If someone wants to use flooded lead-acid batteries for offgrid camping, I usually recommend four 6-volt golf cart batteries in 2S2P (I hope I got that right). A battery hydrometer is an important piece of equipment if you go with FLA batteries.
If someone wants to use lithium iron phosphate batteries for offgrid camping, I usually suggest two 100-ah lifepo4 batteries. A state-of-charge meter is a must-have with lifepo4 batteries. The camper's little four-light "battery charge indicator" is absolutely worthless if you have lifepo4 batteries.
Recharging either chemistry during daytime hours, either with solar or with a generator, is crucial if you want to spend several nights offgrid.
I equipped our camper with a total of 500ah of lithium iron phosphate batteries (one 300ah battery and two 100ah batteries), two 190-watt solar panels on the roof, a 60-amp MPPT charge controller and a 3000/9000-watt inverter-charger (not to be confused with the CONverter-charger). It's capable of charging at up to 85 amps. Used as an inverter, it allows the use of the air conditioning for modest periods of time. If we were to attend the Oshkosh air show, we could run the air at night for 6+ hours but I'd need to start recharging the batteries as soon as possible in the morning.
I may have gone a bit overboard on the battery capacity (actually, I'd like to buy another 300ah battery, giving us 800 amp-hours. It's only money, right?) but we can stay offgrid almost indefinitely. Ok, not indefinitely. But we'd exhaust our water and food supplies before we ran out of electricity.
Now, with all that being said, it's a real bummer that my health issues have prevented us from doing any offgrid camping this year. We were able to camp this year at the Straits State Park during the St. Ignace Car Show, but not without taking a handful of pain killers every day. Ok, not a handful. But I'm in trouble if I don't take them exactly on schedule.
Remember, your camper consumes energy 24 hours per day. So you need to be able to recharge your batteries PLUS continue to provide power to your camper's 12-volt devices during the day.
My 12-volt fridge's freezer compartment sure does a nice job of keeping ice cream nice and cold. M&MS are great if kept in the freezer too. Don't laugh til you've tried frozen M&Ms.
