I was so ready to love a 12volt electric fridge. I wouldn't ever need to buy ice again. I had heard that they suck down the juice, but I just kept the trailer batter separate from the Jeep battery. I even designed the ice chest area to be big enough for the 12v chest which is a little taller. Then I installed cig lighter plug right next to the ice chest place. Lovely. We packed cold food & drinks into it, and took a trip. When we stopped for gas I checked the fridge & joyfully reported that it was even colder than when we left. It was working! this was gonna be great!
When we got to the camp spot, I pulled the ice chest out out the Jeep (where it was plugged into the Jeep's cig lighter when the car was running. And set it in the shade. not long later I checked it again and it was room temperature! Already!
I just couldn't believe it. On closer inspection I saw that the 4" fan hole is a straight through, and just as soon as you unplug it from the 12volts, all the cold air drifts out the fan hole, and that very same thingy that makes it cold- is hot on the other side- and it's now letting that heat drift into the ice chest.
So finally I came to understand what everybody told me. These things are junk, - unless of course you feed them voltage full time.
I soon gave the thing away - which was how I got it too.
So NOW what we do is start with frozen 1.5 liter water bottles in a regular ice chest, Those will easily last all weekend. Great as there is no mess, and we can drink the water too.
For extended trips, when those frozen water bottles start losing their cool, we take out huge cups (tupperware pitchers with tight lids actually) into any fast food place and fill 'em with their free ice. Only 1 place ever wanted to charge anything and that was like 15 cents. Good deal, and I always make sure to have a couple of coins in my pocket just in case that happens again.