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The Best Ice Packs
Ice is cheap and effective, but it can leave a sloshy mess in your cooler. Is there a better solution for keeping the contents of your cooler cold?
What You Need To Know
Ice packs promise to keep your cooler cold without the hassle and mess of dealing with cubed ice. Most of the packs are filled with nontoxic chemicals, some of which are supposed to stay cold for a prolonged period of time.
To find the best ice pack, we selected eight models priced from $3.49 to $29.99. If a manufacturer offered multiple sizes of a product, we chose the largest available. Most of the packs were hard-sided, but we also included two soft-sided ice “blankets” meant to line the bottom of a cooler. Only one product is filled with plain water; the rest use proprietary nontoxic liquids or gels. We froze the packs for 24 hours before each test.
To get a preliminary read on their ability to stay cold, we started by removing the ice packs from the freezer, affixing a thermometer to each, and tracking how long they took to warm from a baseline of about 32 degrees to 50 degrees. With the exception of the two ice blankets, which were both completely thawed in less than 7 hours, all the ice packs stayed below 50 degrees for at least 12 hours. We did find that ice packs that weighed 2 pounds or less called it quits sooner than larger 4- and 5-pound packs.
We saw the same trend when we placed the packs in identical pools of 75-degree water and tracked the temperature of the water as it chilled and ultimately started to warm up again: The smallest ice packs had minimal cooling power, and the ice blankets weren’t much better, but large ice packs worked well, keeping the water cold nearly twice as long (as much as 7 hours) as the others.
So far only the obvious was clear—larger ice packs stay colder longer. So couldn’t you just use more of the small ice packs to achieve the same result? To find out, we lined the bottom of identical large, 38-quart rolling coolers with as many packs of each model as would fit without overlapping—between one and three packs for each model. We filled another cooler with 5 pounds of loose ice (the smallest amount we could buy at the grocery store) to see how plain ice would compare. We loaded 24 cans of 40-degree seltzer and soda into each cooler so that they were all about half full and tracked the air temperature inside each cooler. Every hour we removed a can from the same spot in each cooler, opened it, and recorded the temperature. Our goal was for the cans to stay under 50 degrees, which we found to be a nice drinkable temperature.
The good news: With size accounted for, every ice pack kept the contents below 50 degrees for more than 8 hours, a reasonable length for a party or tailgate. But we didn’t stop there. The cans in the two coolers with ice blankets warmed up to an unpalatable 60 degr...
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