If your still using a cooler filled with ice, you proboly still enjoy eating spam for dinner! Getting and keeping ice in old school coolers is challenging, espically in the remote areas we all play in.
The Fride/Freezers run off your vehilces battery, and are capable of refrigerating or freezing your foods and beverages. They draw so little off your battery, you can run them for days (Depending on your vehicle battery size) without draining your battery.
We are particulary fans of the ARB units. They use a full compressor refirdgeration system, just like your home fridge, but are so efficent battery use is super low. Let me put it this way, we have left our 63QT ARB running in chase 1 (Ford F350) for 4 days, without starting the truck, and had no issue when it came time to start. Go ARB.
We use ARB Fridges in our chase trucks at Best In The Desert, and SCORE events.