Greetings to all the masters. This winter homemade It will be useful for fishermen, hunters and for everyone who is on the street.
Hot-water bottles are catalytic and electric. The former have a number of disadvantages - the smell of combustible material, it is necessary to pre-ignite and so on. As you know, gloves, mittens, mittens only keep your hands warm. I decided to make a quick home-made heating pad from improvised means. I had in my possession the simplest inexpensive bank purchased at Aliexpress. Actually, he presents a plastic box with contacts for two lithium-ion batteries of the 18650 format and with a charging board on the popular TP4056 chip. At the end of the power bank there are two USB connectors for a standard charging cable.
As a heating element, I used a carbon carbon fiber wire also purchased at Aliexpress at the time.
It consists of carbon fiber protected by heat-resistant insulation. This wire has an extensive scope of application - underfloor heating, incubator heating,, in warm blankets, seat heating in car etc. The supply voltage of this wire is from 3 to 380 V, resistance per 1 m = 33 Ohms, heating temperature up to 200 ° C, diameter 3 mm. Earlier, I made car seats from this carbon fiber wire (see the article “How to remake a car seat cover for car seats on a carbon fiber wire”). It has been working perfectly without breakdowns for the second year already. Carbon fiber wire is much better in comparison with nichrome, it has many times greater mechanical resistance.
You can use one or two lithium-ion 18650 batteries to power the device.
The list of tools and materials
Stranded copper mounting wire, diameter 1.5 mm;
- carbon fiber wire;
- 1 W LED with a radiator;
diode 1N4007;
-switch;
tactile button;
-aluminum spray can from deodorant;
-heat-shrink tubing;
- a sharp knife;
-drill;
soldering iron;
-glue;
multimeter.
Step one. Making the heating part of the device.
Since carbon fiber does not solder, we apply the following method of connecting to a mounting wire. Having departed 3-5 mm from the edge of the carbon wire, we make an incision of the insulation with a sharp knife and tightly screw the mounting copper wire directly.
Empirically, I picked up the length of the carbon wire 40 cm. Fold in half, make contact in the middle of the wire and along the edges. As a result, we get two heating elements of a heating pad connected in parallel. The total heater current in this case will be about 1.5 A.
From an aluminum spray can from the deodorant, we make a U-shaped lid according to the size of the crib.
Glue the “Secunda” glue to the carbon fiber wire to the inside of the aluminum cover. It is advisable to evenly distribute the wire over the surface of the lid.
We isolate the joints of the carbon wire with the copper wire using heat shrink.
We put heat-insulating material on top of the heater in order to direct the heat flow to the aluminum casing and not to heat the casing itself.
Second step. Assembly scheme of the entire device.
We drill a hole in the casing of the power bank to output the wires of the heating element. We insert the wires into the hole and put the aluminum casing on the body. We drill another hole for the heating switch and install the toggle switch.
We solder the circuit of the device. My battery was already with contact plates - this simplified the assembly. Heater soldered wires directly to the battery. Glue the LED for the flashlight to the end of the housing. In the LED circuit there is a 1N4007 diode (you can use any one with a current of up to 1 A), it is designed to reduce the voltage from 4V to 3 V, so that the LED does not fail prematurely.
As a flashlight switch, we use a tactile button. We also glue it to the side surface of the casing of the bank.
Step three. Device test.
The flashlight shines perfectly. Turn on the heating mode. In two minutes, the surface of the aluminum casing of the heating pad is heated to 43 ° C. Not a bad result.
The tests on the street were successful, the soft heat of the carbon fiber wire lasted about 1.5-2 hours. I used one 2800mAh battery. When repeating homemade, everyone can calculate the heating element individually, depending on the size of the case, the number and capacity of the batteries, the supply voltage and the length of the heater. You can reduce the resistance of the heater to increase the temperature of the heating pad, but then it is advisable to use two batteries so that the operating time is not significantly reduced. You can add an LED to indicate that the heating mode is on by connecting it through a 500 Ohm resistor to the heater.
An interesting homemade three-in-one turned out. The power bank can be used for its intended purpose - recharge the mobile phone, power some devices. Added the function of a heating pad and a flashlight relevant in our climate.
More and more clearly all the work can be seen in the video
Maybe someone will find this description of homemade useful. Thank you all for your attention, health, all the best, good luck in life and work!