So I bought an ARB (Engle) fridge back in 2008. In 2010 I bought a new Xterra. That fridge pretty much lives in the back. Very rare does it come out. Turn it on as I need it, off when not.
I'll take off on weekends and run it for a couple days. It's plugged into the factory accessory outlet and draws off all factory wiring. The battery was replaced at 6 months with an Oddessey in stock size. It is now 6 years old. I did add a small solar panel. 70W rated but after charge controller it is lucky to make a real 50W. It is mounted flush to the roof, so no optimal sun angle stuff. I prefer to park under trees for shade as well. It's not happy if you try to run in freeze mode all night long, but fridge mode is just fine. I've left it parked and the fridge running for 36 hours and it still starts fine. It does need a solar panel to pull that off as it isn't happy in a hot car without a charge after half a day.
Oh, a dead battery is possible. Wait. Solar will recharge. At worst I may have to wait a few hours and leave mid morning instead of early morning. Solar will still charge even with shade (just not as well). I don't have issues with this. I don't find myself parking in caves and needing to run the fridge. I do have jumper cables and rarely am I that alone. And if I am that alone, I have the time needed for a solar recharge.
I did have a dead battery once. In a parking lot with about 100 friends. Summer with the fridge running hard for the better part of the day. before solar. with a bad factory battery (found out I was part of a bad batch).
So 6 years running this way. Do I have plans to change it? No. I might put a new battery in simply because the old one is getting old. Batteries are not known for a long life in Arizona.
