Introduction: Heated Coat

By 300MPG.org
About: Ordinary guy with no special skills, just trying to change the world one backyard invention at a time. See more at: http://300mpg.org/ On Twitter - @300MPGBen and at Ecoprojecteer.net

In my part of the world, winter is starting right now. 

As I have no basement, and my garage is not insulated, I find myself doing most of my work out in the cold.

I also have a homebuilt electric car, in which the heat isn't the greatest. On top of that, my wife's car has a heated driver's seat, which only makes me all the more jealous!

All of that together got me thinking.... What if there was some way to stay warm both outdoors and on the road?

The answer is the HEATED COAT!

Come along with me as I show you how anyone with basic sewing and electric skills can create inexpensive and WARM workwear for the thrifty Do-It-Yourselfer!.

You can check out my other DIY recycled projects at: http://ecoprojecteer.net/
All of my clean transportation projects (electric car and more) are at: http://300mpg.org/

Step 1: Tools and Materials

The two main components are a coat and an an appropriate electric heating element.

To start with, I went to my front closet and pulled out my work coat. This is a 3/4 length coat with a cotton duck exterior and "Thinsulate"-type insulated lining. It's a bit worn, as it is what I wear in the winter to shovel snow, work on cars, and do other physical and dirty work.

That also means I'm not afraid to cut it open and start modding the coat!

For the heating element, I pulled it from a heated back massaging chair cover I already purchased from the thrift store. Most of these devices are actually 12V DC, but they use a power adapter to run them from household AC electricity. Before buying I looked through several of these and chose one with the highest power rating, assuming that it was likely to have the most powerful heating feature. (Cost was $5.00)

Besides the coat and heater, we will also need both sewing items and electrical items. So, break-out BOTH your sewing kit and your electronics kit and have handy items such as:
  • Heavy needle and thread (denim or canvas weight)
  • Pins
  • Seam ripper / Scissors
  • Soldering iron / solder
  • Wire Strippers and side-cutter
  • Shrink Tube
  • Heat Gun
  • Infrared thermometer
  • Ruler / Tape measure

Step 2: Extract the Heater

The first major step is to remove the heating element from the heated seat cover.

Flip the seat cover over, and you'll notice a zipper that runs a fair length of the back. Open it up. If it doesn't open far enough, use a scissors to extend the length and open the entire back.

Inside, you'll notice a number of wires. Most of these run to the massaging motors, but there will also be a main power connector, and a cord that goes out to the hand control.

Locate the heating pad. Generally, it is going to be two slightly thicker wires that are going to something that is NOT one of those lumpy motors.

It is most likely glued under a layer of foam, so gentry peel back the foam to get at it. The heating wire itself is embedded in a cloth-like material, along with a thermal cut-off device.

Snip any zip ties that are bundling the wires together, unplug any quick release connections, and remove the heating pad AND the main power cable. Snip both of them off with a side cutter, leaving yourself as much extra wire to work with as you can.

Step 3: Prepping the Coat

First, determine where exactly you want the heat. Maybe it's in your shoulders, or maybe it's in your lower back. You might want to try on the coat and have an assistant pin the location.

I decided on right out the middle of the back.

The heating element will go INSIDE the coat, between the lining and the shell. (This style of coat is only two layers - the insulation and liner are one integrated element.)

I also "pre-wired" the heating element. I simply twisted together the two wires of the heater to the two wires of the power cord so that I would know how much length I had to work with.

Next, I opened up the coat and laid out where I wanted the heating element to go. I also looked to see where I would want the power cord to exit the coat. I decided on the right-side bottom hem, as that would be a good place for it to be when I'm driving a car - near the seat belt and 12V car power outlet. (If you primarily want the heated coat to work with a small 12V battery, you could make the power cord exit into a pocket, where you would store the battery.)

I also decided that if I was going to cut a hole for the cord, that may also be a good place to insert the heater.


Step 4: Wiring

Wiring the heater is pretty simple.

It just needs the two wires of the heater connected to the two wires of the original DC power connector.

I stripped the ends of all four wires, then slid on a little shrink tube, and soldered the two pairs of wires to each other. Slide the shrink tube over the bare connection and heat it to shrink into place. Electrical tape would work fine too.

While I had all the components on my bench-top, I measured the heater with the multi-meter. While you can use Ohms Law and a bunch of other electrical math, I just used my multimeter to measure amp draw through the heater. It was about three-quarters of an amp. Multiply that by 12V, and you'll see that it is about a 9 watt heater. That doesn't sound like a lot, but it's enough to stay pretty warm.

My non-contact thermometer measured it at 114 degrees F. 

Step 5: Sew It Up!

With the heater wired up to the power plug, it's time to sew the whole thing into the coat.

I made a slit several inches long in the bottom right of the coat to allow inserting the heater, AND be able to get my whole arm in there.

I slid the heater up into the coat into the correct position, as marked earlier with pins.

I stitched just the four corners of the heater. That is, I stitched from the lining through the corner of cloth material on the heater, and back through the lining. Only the corners are stitched, and the stitches do NOT go through the back exterior of the coat.

When finished, you just see four small bits of looped string on the inside of the coat.

The power cord needs to be connected securely to the coat, as the cord will get pulled and handled a bit when plugging and unplugging it. I stitched through the entire bottom edge of the coat, up and over the cord, and back around again, several times.

With the cord in place, I sewed the cut in the lining back shut. When done the only thing that really looks different is the pig tail of the power cord sticking out the bottom of the coat.

Step 6: Power It Up!

The coat can easily be powered at least three ways.

It already came with an AC power supply, which converts household current to 12V DC. This might be handy for working in the garage for hours at a time on a cold winter day. I would just plug right into the wall for steady power.

In an automobile, the coat can be powered with a 12V cigarette lighter plug. Keep in mind that some cars provide power to that outlet only when the car is on, and others are always powered-up.

My original idea for this heated coat was that the primary use would be in cars. If you car doesn't have a good heater, the electric-heated jacket gives you warmth right away. Even if you have a great heater in your car, you still have to wait for the engine to warm up. Also, heat usually points at the feet in your car. Heat in your back keeps you more evenly heated, for greater comfort.

I also wanted to be able to run the heated coat from a battery, but lead-acid batteries are heavy. I also had a few HiMH cordless drill batteries, but those were higher voltage and still too big to fit in a pocket. I happened to stop at the big box home improvement store and saw that they had a commercially-made electric heated jacket. That one was powered by a tool company's small Lithium battery system.

When I got back home, I realized that I did have ONE small Lithium battery from a Craftsman 12V tool. The electrical contacts on that battery are basically 1/4" female connections. I snipped a plug off an old power supply which had the right size barrel connector for the coat, and stripped the wires on the end. I crimped-on two male spade connectors, and pushed them into the battery. The barrel end of the short cord plugs into the coat, and the battery goes in the pocket.

When done using the battery, I pull the two connections out of it and recharge it on its normal charger.

Step 7: Now You Make One!

If you also do a fair amount of work outside in the cold, or would just like to be toasty warm in your car the moment you hop in, maybe you too would like to make a heated coat!

Just a few thoughts on things I learned working on this project...

If you are good at sewing, there's no reason not to use a dress coat, a brand-new coat, a leather coat, or whatever your favorite winter clothing is. I used this coat because it IS what I wear outside in the winter. Frankly, I'm not that good at hand-sewing and making it all look as good as somebody with more sewing experience.

Maybe you want the cord inside your pocket. If you plan on mainly running the jacket on a battery, decide where you want the battery to go. You might want it in a zippered pocket, or one that you don't use otherwise. Sew the power cord so that it goes to that pocket. Then, it's always out of the way, but right where you want it when you plug your battery in.

Some styles of coats have a removable liner. If the heater and cord are sewn to that, you can easily remove it and still be able to wash the coat.

When I saw the heated coat at the store, it was $200!

With a little bit of DIY, a "can-do" attitude, and a $5 budget, I was able to to build a coat every bit as good, and I'm sure you can too!
See more of my recycled DIY projects at: http://ecoprojecteer.net/

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