If cold feet are ruining your skis days or winter hiking, you should consider a pair of rechargeable boot warmers. Huge improvements in battery technology over the past few years have made these systems much more reliable and effective.
As someone who has poor circulation and feet that are always cold when I ski, I have been using Hotronic foot warmers in my ski boots since they first came out in the 1990's. Hotronic's contain a heating pad that goes under your foot bed, which is connected via a wire up and out of the boot to a rechargeable battery pack. The system keeps your feet warm for hours in your ski boot and beats trying to stuff disposable foot warmers in your boot which always get in the way.
Early Hotronic models were plagued by memory issues related to the batteries and many ski stores stopped selling them due to customer returns. However, over the last few years, largely thanks to new battery technology, Hotronic's have made a big come back. The new models do not need to be fully discharged before charging (a major issue previously), they last about twice as long, charge twice as fast and the battery won’t lose “memory”. In all, that’s a major improvement.
I recently tried the redesigned Hotronic Power Plus M3’s, which will keep your feet very toasty for about five hours per charge on the second setting. They are fairly easy to install and work very well. If cold feet spoil your skiing fun, this is money well spent. The Power Plus m4’s are slightly larger and offer about 30% more battery length for about a 20% price premium. However, take a look at the battery pack before you buy the M4's and make sure you don't think it will get in your way as it is pretty big. As far as ski boot warmers and foot warmers go, Hotronic is your best option.
If you have never installed Hotronic boot warmers before, it’s probably best left to a ski shop. You need to make slits in both the foot bed and the foot liner in order to run the main cable and this is something that is likely to make you squeamish if you just spent a lot of money on new boots.Expand Review