I tried a DC compressor fridge once and it did not work well for me because it ran continuously. I think the problem was the fan and area was set up so that most of the air the fan moved was just circulating and I wasn't getting enough draft through the original vents to keep the efficiency up.
That was several years ago and I'm thinking about trying again this time doing things a bit different. The main thing will be that I will add baffles so the fan also forces the air flow through the compartment. If that isn't possible, will add a temperature controlled secondary fan to force air through the compartment. Or a combination of the two. By keeping the air cooler, it will increase the efficiency which will reduce run time.
