I just put mine in the garage, loaded it up with warm drinks, and plugged it into the wall. I figure it is best to start out with everything cold and not make the fridge do the hard work on the Jeep battery. Then, I'm going to drive my Jeep to work tomorrow, let it sit all day, then pull cold drinks out as I go watch a football game! (I'm a middle school principal). I think I will really enjoy this thing! Btw, it ran perfectly when plugged into the 12v in the back of the Jeep. I set the compressor speed to auto and the voltage guard to 10.7, for now. I may raise it to the high setting, which I think is 11.7. It is VERY quiet, even when on high speed.