A common problem with coolers as they age or get left out in the sun is that the lid can begin to warp so that it no longer sits flush with the body of the cooler.
This actually seems to be more common with the higher-end roto-molded coolers than it does with the cheaper coolers like the Igloo brand.
So why exactly does this happen and what can you do to stop your cooler lid from warping over time?
NOTE: If you cooler lid is already bent check out this article on how to fix a warped cooler lid.
Keep It Out of Direct Sunlight
The biggest cause of cooler lids warping is exposure to direct sunlight.
When coolers are exposed to direct sunlight the plastic exterior of the cooler gets extremely hot.
On a summers day the lid of a cooler in direct sunlight can get as hot as 140ºF/60ºC. This is enough to begin to make the plastic soft.
While the top of the cooler lid is hot the underneath is cool and this difference in temperature, as well as the difference in cooling rates can cause the lid to warp.
UV exposure and sun damage could also increase the chances of your cooler lid warping.
To avoid these extreme temperatures from the sun and the UV damage simple store your cooler in the shade wherever possible. Not only will it stop your lid from warping but ice will last longer in your cooler too.
Buy a White Cooler Not A Dark Cooler
Not only do light coolers keep ice longer than dark coolers but they are also a lot less prone to warping than dark coolers.
This is due to the fact that the surface of dark coolers can just get so hot in direct sunlight which is one of the major causes of warping.
The below video shows the difference in temperature between a white lid cooler and a dark lid cooler.
You can see that in the same conditions a light lids were only 96-100ºF/35-38ºC in direct sunlight while the darker lids were a much hotter 123-150ºF/50-65ºC.
That is a massive difference in surface temperature and could easily begin to soften the plastic these coolers are made from. You can see why a white cooler is less likely to warp than a dark cooler.
Don't Pull Down The Rubber Latches
It also seems that coolers with pull down latches tend to warp upwards at the corners. This could be due to the pressure being applied unevenly to the lid of the cooler.
Because all the downwards pressure is being focused at the latches this could cause the cooler to warp when exposed to high heats (like when they are left out in the sun).
It's possible that leaving the latches undone could prevent this warping from happening.
While you might not want to do this while their is ice in the cooler it could be a good idea to leave your cooler unlatched for long term storage.
Bolt The Corners Down During Long Term Storage
To even out the downwards pressure on the lid of your cooler and to prevent the corners of the lids from warping upwards you can bolt them down during storage.
The bolt will both stop the lid from warped and it will help to undo any warping that has happened.
For high end coolers like Yeti there is usually a hole in the corners of the coolers which are made for padlocks (to make the cooler bear proof).
But get a bolt, washer and butterfly nut and you can screw the corners of the lids together.
This obviously isn't practical when you're actively using the cooler but for storage it can be a great option. It can also be a good way to lock your cooler and prevent people from getting the goods inside it.
Store It Upside Down With The Lid On The Bottom
One of the best ways to both prevent your lid from warping as well as to fix a bend or warped cooler lid is to store it upside down.
By storing it upside down the weight of the cooler body provides an even pressure across the cooler lid.
Because warping is often causes by inconsistent compression by storing it upside down you're minimizing the chances of this inconsistent compression and your lid should stay uniform.