Heated Glove Liners

NOTE: The wire connection method described in this Instructable isn't as strong as it needs to be. An improved method can be found here: Working With Carbon Heat Rope

For many people like myself keeping our fingers warm while outside during the winter poses a constant challenge. More acutely for those of us who suffer from Raynaud's where our body cuts off circulation to the extremities in response to cold exposure. A further complication arises when engaging in an activity such as cycling that requires grasping objects, compressing glove palm insulation reducing its effectiveness. Chemical warmers are bulky, often don't fit inside regular gloves and may not get heat to the fingers where it is needed.

The solution, a pair of thin liners with battery powered heat delivered to the palm side of all 5 digits that you can slide into your favorite glove! The heat is generated from carbon fiber rope attached a glove liner of your choice.

Updated Version

I published an updated version that eliminates the gluing, exposed wires and results in a more flexible glove. I recommend that version instead: Heated Gloves Version 3.5

Process

This project involves attaching carbon fiber heating loops to a pair of glove liners and wiring each to a 7.4 volt battery. The temperature generated drops as the length increases which is why 3 separate loops are connected in parallel. Since we are creating an electronic circuit the carbon fiber needs to go up and down each digit without crossing itself. One loop covers the thumb and back of hand, a second covers the index / middle fingers, and the third covers the ring / pinky fingers.

It is important that the glove is wired as indicated. Since the 2 spots where separate loops meet have the same polarity, there is no risk of a short circuit at that location should the loops touch.

The heating loops are temporarily tacked in place with fabric adhesive, then the wires and optional thermostat are connected. Finally a thin bead of flowable silicone is applied over the carbon rope. This provides a flexible attachment of the carbon to the glove, insulates the loops from shorting against each other, and protects the fine carbon threads from fraying.

A switch and power plug may also be added depending on how you plan on using the gloves.

Warm or Warmer?

The carbon heat rope linked to in the shopping list generates many times more heat than is needed in this glove liner application. Fortunately the rope is a loose weave of 12 smaller bundles of fibers which gives us the opportunity to both stretch our material further and customize how warm our gloves will get ... WIN WIN! After separating the smaller ropes we will re-wrap 2 or 3 of them back together.

A glove I made with 2 bundles reaches about 38 °C when plugged directly into a 7.4v battery, and draws 0.53 amps. That is a temperature close to a commercial heated glove I have used, and a thermostat would not be necessary.

A test glove I made using ALL 12 bundles draws a whopping 2.6 amps and gets hot very fast. So more bundles = more heat and a shorter battery life.

I made a test loop out of 3 bundles and observed a current draw roughly 50% higher than a 2 bundle loop, so I would estimate a glove constructed with a 3 bundle rope to draw about 0.75 amps. That loop was noticeably warmer, though I couldn't get a good reading on my IR thermometer. For any glove using more than 2 bundles of fiber I would definitely recommend using a thermostat switch or multi-setting power controller to limit the peak temperature.

Battery Life

A glove made of a 2 bundle rope drawing a constant 0.53 amps (not accounting for a battery being affected by the cold) might run beyond 4.5 hours on a 2,600 mah Li-ion bike headlight battery, or 2.5 hours on a 1,500 mah LiPo drone battery.

With the extra draw of 3 bundles those numbers could be 3.25 hour on Li-ion, and under 2 on LiPo, BUT since a thermostat should be used the power would cycle so the run time would likely be higher.

Items you may need to order along with links to sample items:

• Carbon Heat Rope: 50 centimeters to 1 meter depending on heat level desired (see Step 1)
• Liner Glove of your choice, preferably without silicon grippers on palm
• 22 AWG Highly Flexible Silicone Covered Hookup Wire
• Fabric Adhesive
• Super Glue
• 1/8" Heat Shrink Tubing: small packs are expensive, so just get an assortment pack
• Small Alligator Test Clips: for temporary clamping, 6 - 12
• Flowable Silicone: also available in most automotive stores
• 5 ml Syringe: for applying silicone, better control and less waste than supplied cone
• 2 x 7.4v battery packs (see battery section)

Optional items depending on design choices:

• Thermostat Switches x 2
• Power Connectors (varies with battery selection)
• Flashlight Push Switches x 2
• Power LED x 2
• Multi-Setting Power Controller x 2

Other items you may already have:

• 3 - 4 clothes pins
• Soldering iron and solder
• Heat source for shrink tubes (BBQ lighter works well)
• Toothpick

Length

Before cutting a section of heat rope, use a piece of string to measure out the longest heating loop, which will be the one running up and down your index and middle fingers leaving a little extra at each end for routing and wire connection. In my case I found 40 cm to be enough.

2 vs 3 Fiber Bundle Glove (see discussion in Overview step)

6 heating loops are needed between the two gloves. If you are making a glove using 2 fiber bundles you will need to cut 1 length of rope since the rope contains 12 bundles. If you are making a glove with 3 fiber bundles you will need to cut 2 lengths of rope in order to obtain the necessary 18 bundles.

Separating Rope Bundles

• Squeeze about an inch from one end of the rope to separate the bundles
• Slowly pull one bundle until the rope begins to bunch up
• Use one hand to gently propagate the bunch downward until the rope is straight again
• Slowly pull the individual bundle again until it comes out
• Repeat until all bundles are separated, it will be much easier once the first 2 bundles are removed

Making the Heating Loops

• Clamp one end of the bundles for a loop with a clothes pin
• Weigh down the clothes pin so you can have 2 hands free for weaving
• Weave the bundles into a single rope
  • with 2 bundles simply wrap one around the other while applying light pressure
  • for 3 bundles alternate passing the outer bundles across the one currently in the center
• Grab both end and pull tightly
• Use one of the alligator clips to clamp the other end of the rope to prevent unraveling
• Replace the clothes pin with another alligator clip
• Lay the rope flat to help prevent it from kinking up

Note: In the gluing step you will need to wait for glue to set after each loop. Rather than making all 6 heating loops at once you can make more efficient use of your time by making the next loop while the glue for the previous one is drying. If working on both gloves simultaneously you can alternate work between gloves.

The goal of this step is to tack the heating loops in place, not create the permanent bond. Apply the fabric adhesive as a series of dots, not a continuous bead. Leave plenty of slack at the end of each loop to make it easier to connect the wires and route them to the back of the glove. For the loop ends that meet at middle and ring fingers, don't apply any glue for the first 1/4 to 1/3 of the finger at the meeting site.

• Save thumb loop for last as it will be the most difficult
• Apply dots of glue along the path for the first heating loop
• Carefully lay the heating loop along the glue
  - if the bundles start to separate when making a tight bend, twist the rope to pull them back together
  - if you end up with a separated bundle at a finger tip the silicone will fill it in anyway
• Allow the glue to set (the glue I used turns clear when it has dried enough to hold)
• Proceed to the next loop

Using a Thermostat

If you are using a thermostat on your project, it needs to be wrapped with heat loop material so it can measure the temperature being generated. The best location for it is the back of hand since the thumb loop has extra material. Make 3 or 4 wraps of the thermostat body and glue it in place.

Thumb Loop

The thumb / back of hand loop will be the most difficult to apply. It will have to be glued in 2 or 3 stage because of how it wraps around the glove. Don't trim the thumb loop too short as loop temperature rapidly rises as the length decreases. Keeping the loops roughly the same length is why the excess is glued to the back of the hand.

Note: The glue doesn't stretch with the fabric so if you do try the gloves on, be very careful when removing them to avoid causing the heating loops to pop loose.

As shown in the wiring diagram since the loop where the thumb and index loops meet have the same polarity, those two loops can be connected to a single wire. The same would apply to where the middle and ring finger meet, however I found it a little more difficult to use a single wire at that location so you may want to use 2.

• Cut a length of wire about 15 cm of the color needed for the end of loop you are wiring
• Strip off about 1.5 cm of housing from the end
• Cut a piece of shrink tubing to 17 mm for the joint
  - 1/8" will work, but if you have a box of assorted tubing 2.5 mm is a better fit for a 2 bundle carbon rope

• Remove alligator clip and slide the piece of shrink tubing onto the carbon rope and out of the way, then replace the alligator clip
  - the very ends of the carbon rope may not be as tightly wrapped as the middle
  - you may need to remove the alligator clip and do some additional wrapping before sliding on the tube
• Tightly wrap the wire around the carbon rope for a good electrical connection
• Apply 1 or 2 drop of super glue to help bond the fibers to the wire
• Trim any excess rope (may be done before or after shrinking)
• Slide tube over the joint and heat to shrink
  - use a piece of foil to protect glove while using heat source
  - a BBQ lighter works well and you are less likely to burn your fingers

After all the wires are attached you can perform some additional gluing where slack had been left previously.

Note: The glue doesn't stretch with the fabric so if you do try the gloves on, be very careful when removing them to avoid causing the heating loops to break loose.

Working with one color of wire at a time arrange your final rope / cable routing. If any of the carbon ropes have untwisted just rotate the wire a few times to tighten them back up. Trim the loop wires to the final length and connect to a longer segment of wire that will go to your power source. If you are using a thermostat it should be connected to the positive line as indicated in the circuit diagram. This connection should be soldered for strength. Then slide a piece of heat shrink tubing over the joint. A 1/8" piece of tubing managed to fit around up to 3 wires for me.

I show pictures for one glove where I wired every loop separately and a second glove where I combined wires for adjacent loop ends that had the same polarity.

Power Switch
Since the aim is to use these gloves inside a heavier glove an optional switch would best be attached to the lead wire near the battery rather than on the glove itself. If using a switch you could also add an LED between the switch and glove to indicate when power is on.

Power Plug

You can choose to either make the lead wires long enough to reach your battery, or install a DC barrel connector on the glove and make an extension cable that goes to the battery. Pick the option works best for you.

Applying silicone along the heating loops will protect them and provide a flexible bond to the glove.

Tips:

• The less silicone you use, the more flexible the gloves will be
• Using a small syringe (without needle) will allow precise placement of silicone as a small continuous bead
  A syringe keeps the silicone from drying out in between applications. When applying directly from the silicone tube the cone fills up with a lot of silicone that ends up being wasted, it also plugs easily.
• Since the silicone flows, only apply it to heat loops that are flat. The outer edges of the glove and thumb will need to be done as separate applications after repositioning the glove once the previous application has set up
• Apply the bead of silicone to the top of the heat loops, gravity will pull it down to meet the glove material
• Use a tooth pick to spread out the silicone and fill any gaps between the rope and glove on either side of the rope
  - save the toothpick for later use, it works as a better spreader once it has a layer of silicone covering the end
• Don't forget to do the spots where the ropes wrap around the glove, or the spot between the middle and index fingers.
• On the back of the hand use silicone to bond the wires to the glove to keep them from moving around
  - doesn't need to be continuous like the heat loops

Applying silicone will be one of the more time consuming steps due to the curing wait times. The package indicates it takes an hour to skin over, so you should probably wait that long before moving the glove to do another section.

Batteries

Each glove is powered by a 7.4v battery pack. They are available in lithium polymer or higher capacity lithium ion. Many suitable batteries can be found on AliExpress, some even include built-in multiple power level output.

Power Controller / Switch

There are several multi-setting heated clothing controllers available through AliExpress, some can be connected inline with a battery pack, while others can be incorporated into the glove itself.
One source I found for batteries / power controllers is here: https://www.aliexpress.com/store/2683007?spm=2114.12010108.pcShopHead_8168168.0

Glove Connectors

Attach a male DC barrel connector to the glove that matches the jack of the battery. Common sizes are 5.5 x 2.1 mm, and 3.5 x 1.35 mm.

Then you should be ready to go enjoy several hours of heated hands out doors.