This is a revised version of my previous project. The construction is simplified, wires are no longer exposed and flexibility is increased.
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 all 5 digits that you can slide into your favorite glove! You can choose to have either the front or back of the liner heated. The heat is generated from carbon fiber rope attached a glove liner of your choice.
Step 1: Overview & Design Considerations
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 separate loops are connected in parallel (fingers are covered by a single piece but it acts as 2 loops because of the way it is wired). Since we are creating an electronic circuit the carbon fiber needs to go up and down each digit without crossing itself. One loop covers both sides of the thumb, a second covers the index / middle fingers, and the third covers the ring / pinky fingers.
- Gloves are turned inside out
- Double sided fabric tape is applied
- Heating loops are laid onto the tape
- Wires and optional thermostat are connected
- Fabric is laid over the tape protecting the heating loops from fraying and concealing the wires
A switch, power plug and thermostat 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. After separating the smaller ropes we will re-wrap 2 or 3 of them back together.
A glove 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. A glove made with 3 bundles would likely reach around 50 °C. 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.
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.
Step 2: Shopping List
Items you may need to order along with links to sample items:
- Carbon Heat Rope: Approximately 1 meter
- Liner Glove of your choice, preferably without silicon grippers on palm
- the construction steps will make the gloves slightly smaller inside, so it is best to choose a liner that isn't super tight
- 24 or 22 AWG Highly Flexible Silicone Covered Hookup Wire: 24 is better for this ver of glove
- Double Sided Fabric Tape
- Kapton Tape (used instead of heat shrink tubing where more flexibility needed)
- Super Glue
- 1/8" Heat Shrink Tubing: small packs are expensive, so just get an assortment pack
- Small Alligator Test Clips: for temporary clamping, 4
- 2 - 10" x 10" squares of polyester fabric
- A thin poly spandex blend with some stretch, prices vary wildly but a local fabric store should have something on sale, remnants, etc.
- Clear vinyl shelf liner
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
- Multi-Setting Power Controller x 2
- Power LED x 2 with appropriate resistors
Other items you may already have:
- Soldering iron and solder
- Heat source for shrink tubes (BBQ lighter works well)
- Parchment Paper
Step 3: Prepare the Heating Loops
Separating Rope Bundles
- Cut a 76 cm length of carbon fiber heat rope
- 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
(see Warmth discussion in Overview to decide whether you want 2 or 3 bundles in your heating loops)
- Each glove requires one full length loop and one half length loop
- Line up 2 - 3 of the 76 cm bundles, clamp each end, then set aside
- Take one 76 cm bundle and cut it in half
- cut additional full length bundle half if making 3 bundle loops
- Line up 2 - 3 of the half length bundles and clamp on each end
Attach Positive Wire to Full Length Loop
- Cut a length of wire approximately 20 cm long
- Strip 1.5 cm of housing from the end of the wire
- Locate the center of the long loop
- Wrap the stripped wire tightly around this location of the loop
- Add some super glue to the joint to strengthen it
- Cover joint with Kapton tape (not shown)
- Set the full length loop aside
Step 4: Cut Fabric Covers
The fabric covers will protect the easily frayed heating loops and will conceal the most of the wiring. Since the fabric is loose and stretchy a pattern is attached with clear vinyl to aid in cutting. You could also use a temporary fabric adhesive spray.
- Turn glove inside out
- Trace the outline of the glove (no need to trace down each finger)
- Trace the front and back of the thumb
- Cutout the traces leaving an extra 1/2 cm from the line you traced
- Cut 2 pieces of vinyl shelf liner large enough to fit the 3 cut pieces allowing for a gap around the border
- Cut 2 pieces of fabric a little larger than the vinyl
- Peel off the backing and lay flat on work surface
- the vinyl rolls easily with the backing on, but will lay flat once the backing is removed
- Place the cut out pieces of paper marking side down onto the vinyl
- Lay the vinyl onto the fabric
- Cut out the fabric pieces
- The fabric won't be stuck to the paper, so pull from the center to separate from template
- Lay the templates marked side down onto the second sheet of vinyl and cut the fabric for the next glove
- if your fabric has different textures on each side and you want a specific side facing up, you need to flip the fabric before laying down the vinyl for the second glove so the pattern is mirrored.
Step 5: Attach Heating Loops
Using double sided fabric tape, the heating loops will be added then covered with fabric. The fabric tape has limited stretch, so apply it in segments rather than a single piece to maintain glove flexibility.
If you prefer to sew the fabric instead, use just enough tape to secure the heat loops.
Heating loops can be added to either the back or front of the fingers. The construction process is nearly identical for both, except for the fabric placement. I prefer the heat on the front of my hands for winter cycling since I'm always grabbing cold handlebars.
Finger Heat Loops
- Apply fabric tape down either the front or back of each finger and press firmly
- go one square past the finger splits so wire and fabric can be secured
- Remove tape backing from the middle finger, and base of the ring finger
- Stick the wire joint below and between the middle and ring fingers
- heat shrink tubing is rigid, so I left it off in this location and just super glued the wire
- the joint should be sandwiched in gold Kapton tape (not pictured)
- keep the strands roughly parallel so they lay flat
- leave a tape gap between the edge for fabric sealing
- it is easiest to only remove the tape backing 1 finger at a time
- secure thermostat to back of hand with fabric tape
- if the heat loops were placed on the front of the fingers you can trim the excess material below the fingers
Thumb Heat Loops
- Apply fabric tape to both side of the thumb pressing firmly
- the loop goes around both sides of thumb to keep temperature similar to rest of glove, cutting it significantly shorter would make it much hotter
- Remove tape backing
- use a piece of parchment paper against the exposed tape to keep it from sticking
- Lay heat loop on both sides of thumb
- start the loop on the side closest to the index finger to help with wiring later
- Lay the fabric covers over the tape
- use the parchment while pressing the first side down
Step 6: Wiring the Heat Loops
Regardless of whether you put the heat loops on the front of back of the fingers, the wiring will be done on the back of the hand as shown below.
- Pull one of the thumb heating loop ends towards the cuff
- be sure it is not crossing the other end of the thumb loop to prevent a short
- Wrap the positive wire from the finger loop around thumb loop rope end
- If applicable wire in thermostat
- Add a length of wire that will go to the positive power supply
- either solder or super glue to reinforce
- Add heat shrink tubing over the joint
- foil is useful for protecting the glove while heating the tubing
- Wrap short length of wire for negative to the heating loop loose end near the pinky finger
- apply super glue and sandwich with Kapton tape
- Take other end of negative wire from pinky loop and wrap it around both of the remaining loose heat loop ends near the index finger.
- Add a length of wire that will go to the negative supply
- either solder or super glue to reinforce
- Add heat shrink tubing over the joint
Step 7: Wiring Routing and Sealing
For the wires that lead to the battery you can either have them exit through the wrist or cut a small hole so they will exit through the back of the hand.
- The heat shrink tubing for the negative wire should run parallel to the edge of the glove so it doesn't sit on the knuckle when the glove is worn
- Apply double sided tape around the border of the back of the hand
- Apply additional pieces of tape:
- around exit hole for wires
- along wire paths to secure them
- near middle to secure fabric
- If you put the heating loops on the front of the fingers you will need to cut a piece of fabric, as the piece trimmed below the fingers won't be long enough
You should then look around the glove for any areas that could use some additional tape and fabric to cover exposed wires or heating loops. Take special care around the index finger area that none of the positive and negative loops will touch each other.
- Carefully trim excess fabric away
- between the fingers you may simply need to cut a straight line
- Turn the glove right side out
- this will be more difficult than it originally was
- it helps to push a finger into each hole from the outside to unkink the fabric
It could be helpful to apply a little silicone to the wire exit hole to prevent the fabric from tearing.
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.
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.
Step 8: Batteries & Controller
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
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.