I have Thermic heaters plugged into a jumper box, which I have to confess I bought for just that purpose. The Thermic heaters were blowing out the fuse of my old Audi when plugged into the cigarette lighter (old car). I have normal (120v) Dry n Warm boot sticks which I could plug into the outlet in the trunk of my new car, but was afraid of blowing the electrical system because of my prior experience. Their packaging has not a hint of what the draw (watts? I'm hopeless at electrical stuff.) is. Nice to hear Dry Guy (appear to be the same as my Dry n Warm) is safe in Wallace's car. The Thermic heaters are 12v, 50 w. It works, which is why I haven't been tempting problems. The Thermic heaters just get warm, no fans. Frankly, they are a bit too warm for extended use. Which is why they probably blow car fuses.