Portable mini fridges and USB coolers

A classic cool box is an insulated box: it slows warming, it cools nothing. After four to six hours without an ice pack its contents are at ambient temperature. Fine for a picnic, not enough for a day in a car.

A Peltier mini fridge makes cold for as long as it is powered. It typically reaches fifteen to twenty degrees below ambient: at thirty degrees outside, that is ten to fifteen degrees inside. It is not a domestic refrigerator and should not be relied on for meat.