I dump the water from time to time when I use a cooler, mainly because I don't like waterlogged butter and cheese and stuff. It probably works out to about once or twice a day (with a little personal cooler), which often corresponds to about when it needs some more ice.
Golfcart wrote:
I usually add salt to the mix to keep it colder longer. Not sure if it actually works, but ive always heard it does lol
Salt wouldn't keep it colder longer, but would keep it at a lower temperature for a somewhat shorter time. If you use enough salt, you could keep frozen things frozen. (Think of the old-fashioned ice cream freezers). The reason is that salt, like most things dissolved in water, lower the freezing point. It's the basic reason why antifreeze works in vehicle radiators, too, to prevent freezing, and why the electrolyte in (charged) lead-acid batteries does not freeze in typical winter temperatures.
The ice wouldn't last as long precisely because the temperature is lower, and hence there's a greater heat transfer from the environment to the interior of the cooler due to the greater temperature differential.
