DIY Heated Gear: Jacket Liner 2.0

The Nichrome Solution.
Last time I used the teflon coated single strand hook up wire that required one long length with the fleece jacket liner (v 1.2).  The liner is very warm but it's not comfortable under my First Gear Monarch jacket, especially around the neck.  It works great with the Fieldsheer Flex jacket, but I wanted something I can use with the winter jacket so it was back to the drawing board.  My solution was to use the nichrome wire and a light weight "wind" breaker.

First step was to get the wind breaker.  I got a Danskin Now® Track Suit with a mesh liner about $10.  It's very light and hopefully the solution I need to fitting under the winter jacket.  A quick test proved that the teflon hook up wire was too hot for the material.   It is likely the 7/38 stranded wire would not do this but I didn't have any and I wasn't about to buy more wire.  Instead, I got some heat shrink tubing for the bare nichrome wire I already purchased when I did the heated gloves.  I found an online source and got a hundred feet of tubing for $16 delivered, a lot cheaper than the little bits I used from Home Depot with the gloves.

Using the nichrome is a little more labor intensive than with the teflon hook up wire that I taped and "sewed" the shirt over.  Both work well, but I suppose which way you do it depends on how much time you have to dedicate to the project.  The teflon hook up wire liner only required a positive and negative power cable, the nichrome liner requires more because of the segmentation.  A longer segment of wire produces less heat; using a single 30 ft segment of nichrome would not provide the heat you would need for a liner whereas a 30 ft segment of the teflon wire is just about right.  This is due to the properties of the wires and something you should take into consideration when selecting wire for your clothing.

I suppose I should go into the differences between the resistance properties of each of the wires but it's not something that I can explain well and apparently my google skillz suck because I can't find the info either.  What I do know based on trial and error is the nichrome doesn't feel as hot as the single stranded hook up wire so I can use it on a variety of materials.  

For the nichrome resistance wire, I cut 5 segments of bare nichrome wire that were 54" (4.5 feet) long and covered them with the heat shrink tubing.  Then I sewed them into the mesh liner of the jacket, 4 in the front and 1 in the back (In the places I normally feel fatigue after a long ride).

After that, I had to figure out how to get power to the heating elements.  I alternated positive and negative wires for each nichrome ends on the heating elements then twisted the matching polarities together, creating a splitter styled wire.  I put a longer wire to go to the other side on the back of the jacket and did the same thing for that side.  A picture is better than my words:

As you can see, the power connections are coming from splitter wires.  Black with white is the ground wire and is split into three ways: one for the top element, one for the bottom element and one to the rear.  The black only wire is positive and is split two ways on this side:  one for top element and one for the bottom.  Power from the controller is split so that wires go to each side of the jacket.   On the other side, the positive is split three ways and the ground is split two ways.  Hmm...maybe diagrams will show it better.

Red and black didn't show up well, but it's left side + and right side - from the connector

After getting heating elements sewed in and power wires tentatively tied in, I connected it to a power supply to make sure the jacket would hold up with the heat.  No problem!  While it was running, I tested the wattage with the digital multimeter but I can't remember what it was right now.  It's not that important because I think they will change once I get the "wire harness" attached to the heating element.

With the clothing liners, I'm sticking with the same SAE style connector I used with the other jacket and pants liners.  A quick note:  Nichrome is hard to solder.  When I did it with the gloves, I used a thicker gauge wire going to the connectors and was able to wrap the nichrome on the inside wires, over it with more copper wires and solder all that together.  For the jacket, I used thinner gauge wires to power so I don't think my twist, cover, solder method will work this time.

Instead, I chose to crimp the nichrome connections like kphenix did.  I couldn't fill with solder because I didn't have any bare crimp connectors.  The cover is hard to get off of the ones I do have.

A quick test on the power supply revealed everything worked fine.  So after 3 days of work, 2 for sewing and 1 for wiring, I have another heated liner that's about 56w.  Meet version 2.0!

Here are links to all of the DIY Heated Clothing posts.  

Homemade Heated Glove Liners

Heated Gear Update

More Heated Gear

Heated Gear Controller R&D

Jacket Liner 2.0

Thanks for reading!
patrice, theWolfTamer