I caved in and bought a 26 litre 12v cooler. After all, I reasoned, my batteries are almost always fully charged during summer. Imagine how nice a cold beer would be on those hot summer days.
Somewhere deep in the recesses of my crusty brain I must have realized that almost any apparatus that stays on for hours and hours ends up hogging a whole lot of juice. This insight about the inherent evil of machines that stay on all day, is incidentally the reason I don't use my propane-powered refrigerator and started thinking about an electric cooler in the first place.
"Why don't you use your fridge?" visitors sometimes ask.
"Because it only makes sense for people who would use the occasional weekend," I pontificate.
"No way I am going to pack propane up here every second week," I whine.
This little, and rather noisy cooler, primarily intended for people with cars, draws 3,5 amps. My system can take this if the sun shines intensely all day. To begin with I turned the cooler off at night and swaddled it in woolen blankets to keep the cold inside, but after only a couple of hours the contents had reached room temperature. I could build a massive chest with thick polyutherane lining for it, but the mass of the contents inside is probably too small to contain the desired temperature over any length of time.
In the end I just quit using it. It's getting cooler outside anyway. Pretty soon my north-facing workshop is going to keep fridge-like temperatures without any prodding from my part, so I just store perishables there, in my old non-electric cooler.
Hermit's verdict: Unless you have a really powerful RE system, this is just another case of trying to imitiate life in the towns, and failing. It's also obnoxiously noisy. It does make sense, though, if you're having guests over and want to camouflage the otherwise perfectly acceptable level of sqalor you live in. Cold beer and hard butter takes the edge off weirdness, it seems.