Thanks to such comfortable insoles, you can warm your feet at any time and continue to warm them for 2-3 hours! What will definitely save you from a cold.
Will need
- Insoles are thick, made of wool or other material.
- Nichrome wire 0.4 mm in diameter.
- Li-ion rechargeable battery 18650.
- There are two USB cables, I think there are some from old gadgets around the house.
- Power bank - housing for a battery with a USB connector.
- Elastic band for fastening.
Everything, right down to the insoles, can be ordered in China at Ali Express.
We make insoles with electric heating
We take your shoes and insert insoles into them. We put it on your feet, everything should fit well without unnecessary pressure.
We unwind the nichrome wire. I rewinded 65 cm, the length is determined experimentally.
From 5 Volts this segment consumes 0.7 A of current. And this is all on one leg.
We make a USB plug, expose and tin the wires. We put heat shrink on the plug itself so that the wire goes vertically down.
Now we sew the central part of the insole with this piece of nichrome wire. The heel is not involved, since it seemed to me that it is not necessary to heat it too much.
You cannot solder wire to nichrome wire. To do this, it is simply wound onto a USB cable and sewn to the insole with threads. Everything turned out quite reliably.
Heated insoles are ready!
A few calculations
So, the battery has a capacity of 3400 mAh and a voltage of 3.7 V, original battery and corresponds to the stated parameters (checked personally). It is inserted into a power bank, which contains a converter that increases the output voltage to 5 V. Consequently, the capacity will be less: 3.7 * 3400/5 = 2516 mAh.
The insole consumes 0.7 A from 5 V, therefore: 2516/700 = 3.6 hours. And considering that the boost converter has an approximate efficiency of 90%, it will be: 3.6 * 0.9 = 3.24 hours.
As a result, the insole will warm its owner continuously for at least 3 hours! In my opinion this is an excellent result.
Tests
We assemble the Power Bank and insert the battery.
We connect to the insoles and check, but first measure the initial temperature and it was 21 degrees.
A couple of minutes later the temperature rose to 49 degrees Celsius.
Insert into boots.
We bring out the USB cable. It doesn't get in the way when walking, I checked it myself.
We sew a fastening from an elastic cord.
Velcro is used as a lock for quick removal.
The finished clamp itself.
This is what it looks like on the leg.
Nothing is noticeable.
In the same Ali Express, you can order ready-made heated insoles, so if you’re too lazy to bother - just buy.
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Original article in English
