WoodythehikerHey Woodythehiker, I know you know all of this stuff - I am posting this for any cooler neophytes lurking about.
Even a cheap cooler will perform well if you keep a few things in mind. Two stories illustrate the point. (1) When I moved my research group from Purdue University to Auburn University, I had to transfer samples from -80C (-112F) freezers and liquid nitrogen cryostorage units at one institution to the other in the late August heat. I transferred 30,000 1.5-mL vials of biological samples (300 boxes of 100 samples each) in 6 cheap 90-quart coolers (50 boxes each). I filled the remaining volume (~50%) with dry ice (~100+ pounds/cooler). Hauled the coolers from West Lafayette, IN to Auburn, AL (650 miles) in the back of my pickup truck. All told, some of the samples were in the coolers for more than 72 hours. When I got to Auburn, the samples were still frozen - I had to use a hammer and a screwdriver to break up the dry ice to get my boxes out of the coolers. (2) I use my 45 quart YETI for Auburn football tailgating and I typically load it according to YETI's recommendations - 28 cans of beverages and a little more than 20 pounds of ice. I load the cooler on Friday and there is still ice in the cooler on Monday.
So, there are a few tricks to maximize the performance of any cooler: (1) Fill the cooler full. This may mean that you need to top off the cooler with ice once the initial bolus of ice has melted and settled. (2) If possible, the material you are storing in the cooler should be pre-chilled. (3) The volume ratio of ice to material should be at least 2:1. (4) Don't drain melted ice (water) from the cooler until you are finished using the cooler. Because water is a better thermal insulator than air, draining the water from a cooler makes the remaining ice melt faster.
WoodythehikerI have a 25 qt. I put 20 lbs of ice 4am Monday and Friday there was still ice in it. It stayed in my vehicle all week in 90 degree days. To be clear, there was very little ice left by Friday but there WAS ice.