We had a full size Coleman electric cooler, but thought a smaller size cooler would be better for our planned road trip.  We purchased the Koolatron P20 18 quart cooler. We just returned from our 5 week trip, and are pleased with the cooler, which ran the entire time.  It fits nicely behind the front seat of our car, and the sound is not bothersome. The size and well-designed handle makes it very easy to carry into the motel room at night. The top opening lid is handy to reach into from the front seat of the car.  We like the fact it is made in North America (Canada).  It did run for up to 4 hours when we were away from the car and the car still started, but we forgot to unplug it one night, and it did totally run down the battery.