I bought a set of these from one of the caravan shops, Streetwize mini dehumidifiers. I’ve photographed them next to my van keys so you can see the scale of size. I think I paid about £21 on the basis that they plug into the mains and dry out, or recharge if you like. So, the gel beads which you can see n the little window turn pink when they have absorbed as much moisture as they can then you plug them in for some hours and they turn blue when they are ready to be used again.
Sounds good but there are 2 problems with them. Firstly, they go pink really, really quickly. I recharged them about 6-7 times and each time was the same, it seemed only like a couple of days before they went pink again. I compare them with the Dry-Bags that I’ve used for years. They’re tiny grains of clay/salt and when they go dark brown indicating they’ve absorbed as much moisture as they can, you put them in the oven and 6-8 hours later they’re very light brown and ready to absorb moisture again. The Dri-Bags can take months to be ‘full’, whereas the Streetwize mini’s take sometimes only a few days. So in those terms they need an awful lot of maintenance.
Secondly, I can’t remember what the leaflet said, but they take hours to recharge to blue. Generally I plugged one in when I was running the generator, which runs for 12 hours on one tank of fuel. Those 12 hours charge my batteries so whilst that’s doing I also charge my phone, razor, laptop etc etc etc. You can only plug one of these mini’s in at a time and after 12 hours it was only just say blue. There were still hints of pink in some of the beads. I run the generator usually once every 3 days, so if the mini is only lasting 3 days, it means only one is ever in use at a time. Personally I find them very inefficient and for the money they cost they are of extremely limited value to me.
Dry-bags on the other hand last for weeks and sometimes months, and then when wet I tend to put them in the oven with the gas lit to 1/4 and leave them overnight. That’s about 7-8 hours. They’re dry by then and ready to work again. Far superior and now I’ve tried a couple of solutions, I will be getting more Dry Bags and sticking with them.