I guess only applicable to the Brits on this site, a few years ago, I bought a couple of Rechargeable Mini Dehumidifier from Coopers of Stortford (www.coopersofstortford.co.uk). I alternate these each week – when “wet” (there is a small window where you can see the crystals – they change colour between wet & dry), you simply plug it into the mains overnight and the crystals inside are dried out. They seem to work very well and the inside of the car is kept dry – my car is in a garage so don’t know how effective it would be if the car is outside. I guess that you could recharge the unit every night if they get wet very quickly.

Regards,

Norman.