- in what temperatures?
- sitting in the sun?
- opened how many times?
- what's the temperature of the items you're adding to the cooler?
Cooler performance seems to depend on:
- how much insulation (as in, thickness & quality)
- some don't insulate the lid
- hack is to drill holes and inject spray foam
- DAP has a white latex rattle can (water cleanup) that's a lot easier to use than the yellow polyurethane based foams - how good is the seal on the lid, and is it held closed adequately
- raised up from the ground, so it's further away from the dust, which includes bacteria and migratory water-foul droppings, among other things...
- required for food service camps
- don't leave it sitting open, both for heat and the above - isolated from the ground (raised, insulation) also takes it away from sun-baked ground
- some sit their cooler on a thick piece of rigid foam insulation
- if raised, that further insulates the bottom of the cooler - keep it in the shade - don't let the sun bake it
- they get baked sitting in tents or in a car, but you may not have a shaded area to stash it
- something sitting on the lid to hold it tightly closed
- cheap coolers may be improved by adding a thin strip of weather stripping to seal better
- old-school on the playa was to throw a heavy blanket, comforter, sleeping bag, etc., over a cooler to further insulate it from the hot playa air (works - I did this in Africa to prevent film from baking)
- more common now seems to be to wrap it in Reflectix or a space/emergency-blanket, to shield it from radiated heat
- some spray the outside with a spray paint that has aluminum pigment for some radiant barrier benefit; not as good as a "proper" shiny-coated radiant barrier - all of: isolated from ground, extra insulation, radiant barrier & good seal - for the win!
- some people build an insulated box to keep their cooler in
- keep the ice in zip-lock bags
- melting ice doesn't get your food wet
- nor gets contaminated by the playa-dust/soil, and holds it in place in the cooler
- the melted water is then potable, for drinks, cooking or use in a swamp-cooler - keep food in zip-lock bags
- protected from the playa dust that will blow in when you open the lid, or falls off of you
- you don't want that dust's bacteria sitting growing in your food
I shipped a cooler home once. From UPS at Keystone. Very expensive.