A ways back I was wanting a small fridge were electrical sonusmption and sub 40 internal temps were a large concern. When in a garage in florida in summer, the dang thing was running so much, it forced me to contemplate adding extra insulation, and making sure the condenser had adequate ventilation, before letting it loose on a 12v battery.
Most people never consider that the fridge does not force things cold, it sucks heat from them, and this heat must then be released to the atmosphere through the condenser.
The better this condenser can transfer heat to atmosphere, the more efficeint the fridge is.
A lot of these cheapo dorm fridges use the metal skin as the condenser's interface with the atmosphere. So if stuffed into a place with no aircirculation, it stands little chance of expunging that heat, and as a result the internal temps never get very low and the compressor runs often and only shuts down by some thermal protection device so it does not burn itself out.
Think what would happen to your engine if you entirely blocked the radiator with cardboard. One of these dorm fridges stuffed into a cabinet or corner with boxes on either side is like covering both sides of your car radiator with cardboard and wondering why the engine is overheating.
The fridge whose energy consumption I was worried about performed extrememy well with more insulation and very good ventilation given to condenser. It could run for 5 days on a group 27 100 AH battery before draining the battery to 11 volts in 80f ambients, and keep sub 39f internal temps.
