Installing heating elements into ski boots

This is how I install the heating element in the ski boots.

 

 

 

This is the Cozy Battery Powered Foot Warmer. It's available on EBay for about $13 a pair. I got 5 pairs for about $70. The product was designed to operate with 2 AA batteries but the heat is very weak and Alkaline batteries will fail in cold weather. Rechargeable NiMH AA batteries does better in cold, but with 2.4volt, the heat is weak and last less then 2 hours. I tested them in my freezer.

 

One cell rechargeable lithium battery provides 3.7v and provide a very good and comfortable heat. Without socks, it does get too hot after a minute. But with the heat troller to regulate the heat, it would be perfect. 

This is the liner for the ski boots.

The insole was removed.

The wire on the foot warmer was cut to length.

A hole was made on the insole to run the wire to the bottom of the insole.

The self adhesive on the back of the Cozy Foot Warmer

On the bottom of the insole, a electrical tape was used to secure the wire.

Strapping tape is better because stronger adhesive, but I ran out of those.

A hole was made on the back of the boot liner to run the wire out.

Now the insole was placed back into the foot liner with the wire running out thru the hole made on the boot liner

A JST plug soldered onto the wire. You can use any type of plug you choose.

I soldered a small LED with 300ohm resister near the plug.

The wire should be secured on the back of the liner with strapping tape.

 

The liner was placed back in the ski boot.

With battery connected, the LED lit up.

The lithium cell I used is 18650 size lithium ion battery with protection. I ordered a bunch of them online from China. They are rated about 2300mAh.

Under voltage protection is a must, if the lithium cell drain to 0 volt, the cell is permanently damaged.

This size of the lithium cell is commonly used in portable cylindrical USB charger or bicycle headlamp. Portable USB charger has a voltage regulator to step up to 5volt.

I don't need 5 volt, plus it's inefficient to run the 1-2 amp of current thru a voltage regulator.

 

 

The battery holder is actually a small flashlight holder. They are pretty cheap ordering online from China.