I wouldn’t have guessed a mini-dehumidifier. For some reason I was under the impression they didn’t work well in the cold. Probably because there’s less humidity in my basement in the winter.
I haven’t done that yet. I figure I just place them on tin foil set in a pot or baking sheet and bake them at 300-400F for a while. When they absorb water they get all gooy and translucent. Once they look white again they should be recharged. The crystals are just a very hygoscopic salt that attracts water from the atmosphere. That water can be driven off with heat. They also sell refill packs.
If you don’t open the chest freezer/fridge much, one charge should last for a while.
BTW, Calcium Chloride is very hygroscopic too. So you may just place a pan with CaCl2 in the freezer if you already have enough CaCl2 on hand. That is also the reason why brewing salts should be kept in sealed containers. Some of them attract water from the air which will dilute their strength and you end up adding less than you think.
+1 on the Eva-Dry. I have 1 in my 7.5 cu ft freezer, and it works quite well.
Note that essentially all this is is a plastic box filled with silica gel beads. But it has a built-in heating element - Just plug the whole thing into a wall socket overnight and it’s good to go again.
You can also use Damp-rid, or some other similar product. I do like that the Eva-Dry is self contained, so nothing to spill.