I am far from a 12v portable fridge expert. The following is just from personal observations.
After much head-scratching, the Edgestar/Whynter/Engel models were my choice due to having an inexpensive Chinese DC power supply for running the compressor when connected to an AC source:
36V 10A 360W. 12V 1A 12W. 12V 2A 24W. 12V 3A 36W. 12V 5A 60W. 12V 8A 96W. 12V 10A 120W. 12V 12.5A 150W.
www.ebay.com
Although never having seen the guts of a Dometic in person, internet searching seemed to reveal a more intricate/proprietary circuit board to power the compressor from an AC source, and possibly, a variable speed type? I'm ignorant.
That ignorance also influenced the decision to go with the simpler for me to understand brands mentioned above. Below is the very simple, not quite true diagram of my Edgestar. The AC adapter is the type DC power supply linked above.
The not quite true part seems to be the dots that show the Ac adapter/dc supply being directly connected to the input DC connections from a DC source. I've seen no DC present on the unplugged DC terminals when connected to an AC source. Seems to be relay action to automatically connect to battery if AC is lost.
I have purchased a number of those cheap power supplies, mainly for others after having seen mine, up to 12V/50 amps to use for dumb bulk battery charging. Much lighter and more portable than typical battery chargers for short, timed , or observed bulk charging. Adjustable voltage output.
Those DC supplies are dated, simple and fairly robust. There are protective devices at the AC input that have stood a looong test of time against trashy AC inputs, and are discrete components that can be replaced.
It would be sad if any brands of 12v fridges have not been thoroughly tested for AC input abuse.
Hopefully someone will provide technical answers, and if not, it's a commentary on resellers of products made elsewhere, with only salesmen extolling features and how to operate.
AC compressors have withstood awful generator AC outputs since my late fifties childhood days when the guy with the only generator around was a local hero going home to home during relatively frequent power outages.