Product review (5 stars): Works great.
When I received this cooler I immediately plugged into a wall outlet and put a remote reading thermometer in it. After about 2 1/4 hours the inside temperature had dropped to 38 degrees. The outside ambient temperature was 77 degrees. 30 minutes later the inside temp dropped to 35 degrees. Next I but 12 bottles of water and 12 cans of soda from our home refrigerator and put them in the cooler. For the next 2 days the cooler maintained a 36 degree temp (76 deg outside). I then took out the chilled drinks and put in 12 room temp bottles of water and 12 room temp cans of soda. The cooler inside temp started at 74 deg. It took 48 hours to cool the water and soda to 38 deg. The instructions tell you to either precool your beverages and food or to use some blue ice packets to assist with the initial cooling.  I then took out the chilled beverages and put in 6 room temp bottles of water and 12 cans of room temp soda and 6 frozen bottles of water. I distributed the frozen bottles of water among the other beverages. In about 12 hours the inside cooler temp was 36 deg. I ran some of these tests with the device plugged into a 12V power supply and it worked just as well. After all of this we went on a 10 day road trip and the device was only off about 12 hours during the entire trip. After the 3rd day we left the cooler in the car running each night and the device never ceased to keep the contents at least 40 deg below outside ambient temp. Be careful the device draws 4 amps of 12v current and it will run a small car battery down overnight. The device does not have any protection for your car battery. I purchased a low voltage disconnect to put inline with the cooler cigarette lighter plug and it worked great. I never had an issue of a dead battery. Here is the link https://www.amazon.com/Low-Voltage-Battery-Disconnect-EC-LVD2/dp/B00BEA5NPW/ref=sr_1_9?ie=UTF8&qid=1476757773&sr=8-9&keywords=low+voltage+battery+disconnect. You have to do some wiring but it is easy. The cooler arrived on time and was well packaged.