ChillTest: Cool Box Ice Test
ChillTest: Cool Box Ice Test
How long your cool box lasts
Download on the App StoreLoad it with ice, leave it a few hours, then weigh the water that has collected. ChillTest turns that into a single heat-loss figure in watts per degree, which belongs to the box rather than to the afternoon you tested it.
While ice is thawing, the inside of a cool box sits at 0°C, and melting a kilogram of ice takes a fixed 333.55 kJ. Every gram of meltwater therefore stands for a known quantity of heat that has got in.
No thermometer to buy, no sensor to pair, nothing left sitting in the box. A measuring jug does the job just as well.
How long 5 kg of ice lasts at 30°C, how much ice a weekend at a festival needs, whether the pricey box really beats the cheap one. Allow for how often the lid opens, sun on the lid and how full the box is packed.
If the ice thawed completely, if ice packs were used in place of ice, or if it was barely warmer outside than in, the run does not count as a measurement and no figure is shown. You are told what went wrong and what to change.
Keep a record for each cool box and cool bag, with its own measurement history, sorted best first. It is your ranking, from your conditions, not a manufacturer's claim.
A cool box at room temperature spends its first ice cooling its own walls. On an 8 kg box that is roughly 720 g of extra melt, against perhaps 97 g of genuine melt in an hour — enough to skew the result several times over. The hour of pre-chilling, with that water tipped away, keeps the walls out of the sums.