Coleman Portable Thermoelectric Cooler, 40 Quart

Engineer here - These thermoelectric coolers work perfectly, AS LONG AS YOU KNOW A FEW IMPORTANT THINGS. Save yourself alot of money (and weight) and buy these over a compressor based unit if you're willing to follow some best practices. First - Prechill your cooler, and any food or drinks you may place in here for a few hours. Thermoelectrics are not great at removing heat quickly compared to compressor units, if you place a bunch of warm objects in here, you won't get the cooling you think you should. In order to pre-chill the unit, purchase the optional AC wall adaptor before you use it in your car. Second - This unit cools about 35-40 degrees F below AMBIENT temperature. If you place this in your trunk in the middle of the summer (where your trunk is 100+ degrees), this unit will only cool to 60F. If you bring an infrared thermometer with you, you can scope out placement for this unit and get the desired fridge (40F) or Freezer (10F) temps you're looking for. you also need to make sure the heat exchanger on the outside of the unit has some "breathing room". I've found in the summer time, that I can place it on my middle back seats, with the heat exchanger side sitting inbetween the driver and passenger front seats, and if I point my A/C vent directly at it, I can achieve temps as low as 15F inside the cooler. You can basically make small adjustments to your vents to raise or lower temps at that point (once again, having a cheap 15-20 dollar infrared thermometer makes this possible/easy). Third - Realize these units use about 3-4 more electricity than their equivalent compressor based counterparts. This means you can probably run one for about an hour or two off your car battery before it's dead, but that's it!!! If you plan on using something like this long term at home/office, or especially if you plan on using it off-grid a lot, you may be better off with a compressor based unit so you don't run out of/use too much electricity. This unit hooked up to the AC wall adaptor will pull 72 watts of power continuously, if you leave it running 24/7 at a standard rate of .12cents per kWh, it'll cost you 6 dollars a month to keep it plugged in. I only use this unit on trips where I'm in our car a lot. Alternatives - If you need something that uses less power for off-grid or long term use, and you don't mind the extra 10-15 lbs worth of weight, I recommend that you get a compressor based unit instead. They are pricey, but I did find a Massimo 50qt unit at costco for only 300 bucks (so only twice the price of this thing). Compressor based units also generally involve auto-shutoff battery saving features, and better temperature control that you don't need an infrared gun to monitor ;-). Bonus tip - Amazonbasics sells some Large rectangular ice packs that fit on the shelf mounts PERFECTLY. I purchased some of those to create a mini-freezer within this cooler. Worked great on a 12 hour long road trip. Frozen food only got up to 15F, and the refrigerated side stayed around 30-35F for the whole trip. Makes this unit quite versatile. Have fun!!