Fridge, 12V Cooler, Or Ice Cooler?

My truck has the factory installed fridge with an apu. The apu will keep the batteries up so it runs all the time. My previous truck had a fridge but no apu. After 10 hours it would automatically shut off or sooner if voltage drops below preset threshold setting. That truck was not set with optimized idle system and it would idle all night if the cruise was set. So on weekends I had to empty it and restock it.. got old fast..

APU:

Auxiliary Power Unit

On tractor trailers, and APU is a small diesel engine that powers a heat and air conditioning unit while charging the truck's main batteries at the same time. This allows the driver to remain comfortable in the cab and have access to electric power without running the main truck engine.

Having an APU helps save money in fuel costs and saves wear and tear on the main engine, though they tend to be expensive to install and maintain. Therefore only a very small percentage of the trucks on the road today come equipped with an APU.

Coleman 12v cooler here, but i got a thermostat to put in line off of eBay for about 6 bucks so i don't have to worry about unplugging it. Now it seldom ices up on the cooling fins and doesn't freeze things in cooler weather.