A Bit of Background

It's been a difficult winter so far this year for those of us who enjoy getting out for a ride or even just want to commute to work on our bikes. Those who know me are aware that it takes pretty low temperatures to keep my off my SV650s but even I don't like the prospect of getting out when the temps get into the low 20's(F) and below.  I usually can pu a few hundred miles a month on my bikesthroughout the Nashville winter, but this year has been rather lean. Add to the low temps more snow and ice than usual and you can see why it's important to be able to take advantage of clear, dry days, albeit cold ones.

Now one way to combat the cold is to layer lots of clothing under your riding gear. This can work ok to point but let's face it, you're only going to be able to put on so many layers before you look like Randy from "A Christmas Story" and your ability to move comfortably will be similarly compromised. The other option is electrical heating.

Two years ago I installed heated grips on my SV650s and this was one of the best investments I have made for increasing comfort when riding. Heated grips let you wear lighter gloves than you would normally and also let you ride in much colder weather than you normally would with your heavy gloves, but I digress. Since the temperatures have been so low this winter I started looking at using some more electricity to keep me warm elsewhere in addition to my hands.

I began shopping around for heated vests and it turns out these aren't that cheap, starting at about $120.00 or so for a Tourmaster Synergy Unit. That's actually not a bad price but I'm often looking for the cheap less expensive way out.  I recalled seeing an article a while back on a popular motorcycle forum where a rider electrified his jacket liner for a few dollars in parts and a bit of time sewing. "Aha!" I thought, "this sounds like my kind of solution!" and thus I started on the path of adding electric heat to one of my motorcycle jacket liners.

Disclaimer

The following is for informational purposes only and  simply a detail of what I did to create my own do-it-yourself electric vest. I do not claim to be an expert in performing this procedure nor do I make guarantees about the safety or operation of someone else's attempt to create a similar item from the details that follow.  If you are not comfortable working with electricity, soldering equipment, or even needles and thread I would not recommend you attempt to create your own version of what I describe below. That being said, choosing to use the below information means you are doing so at your own risk. I am not responsible if you wreck your vest or liner, damage your bikes electrical system, or set yourself on fire. You have been warned.

The Materials

Here's the list of materials I used to make "electrify" my vest from my Joe Rocket jacket.

●      *75 feet of 24 gauge wire (2 conductor) - this will be the heating "element"

●      12 inches of 18 gauge wire

●      SAE connectors

●      Heat shrink tubing

●      Joe Rocket liner vest

●      Poly /cotton thread

●      Rotary lamp cord switch (optional)

Tools used:

●      wire cutter/strippers

●      soldering iron and solder

●      sewing needle

●      multi meter that can read out voltage and resistance

●      small Philips head screwdriver (for the optional switch)

*the exact length will be determined my measuring resistance and cutting to reach the target ohms. Having a bit more than the recommended length to start with is advised.

Determining the wire length

The first thing I did was get out my multi-meter and test the resistance of the wire I purchased, which in this case was a 75ft spool of 24 gauge speaker wire from Radio Shack. I’m not saying this is the best wire for the job, but it was available and inexpensive ($4.99 for the spool). My goal was to have about 3 to 3.5 ohms of resistance which would deliver about 50 to 60 watts of power. Lower resistance would cause the wire to become dangerously hot as it would draw way too much current. Too much resistance and heating ability would be compromised. Since most commercial products are claimed to draw around 50 to 60 watts, this became my goal as well. You can click the image at the right to access a calculator script you can use to see how this works.

Since I started with a 75ft roll of wire I wanted to test the resistance of the full length to determine where I was starting. This being two-conductor wire I tested only one of the two wires. At 75ft the resistance came to 3.1 ohms, right inside the target range! This was going to make it easy for me, but what if the reading had fallen out of my target range?

Too add more resistance (ohms) you need to have more length of wire. Likewise, to decrease it, you would cut your wire shorter. There are some calculator pages on the web that can give you a rough idea of the expected resistance of a given length of a certain gauge wire, but one has to take into account the variances in the quality of the wire, what bends it will make along its path, etc, so I didn’t (and wouldn’t) rely solely on specs but instead use them as a starting point.

Again, this was 2-conductor wire so I had two choices, cut the length in half and solder the two wires together or peel the two conductors away from each other so I had one long single conductor wire. I chose to cut in half and solder them together at one end. My reasoning for this was thinking ahead about getting this entire length of wire run in the vest and how many times I would have to have it going up and down and up and down the material. Starting with the two conductor wire would mean half as many runs up and down the vest to be sewn in.

After I stripped ends and soldered the two wires at one end of the length, I got out my meter and tested again. The resistance had gone up just a bit to just under 3.2 ohms so I was still in the ballpark. These results also indicated that since I only needed half of the spool of wire  I purchased, I most likely would have enough left over to make a second vest. Since everything was going so well at this point I figured a bit of testing was in order.

The First Test

Before moving further I wanted to see how this would work so I ran out to the garage and grabbed one of my extra motorcycle batteries (yes extra! Wanna buy it? email me). Honestly I was a bit apprehensive about just connecting a length of wire to a motorcycle battery but the theory seemed sound. I measured the resistance yet again and the proceeded to clamp the wire ends to the posts on the battery. To my surprise (and relief) very little happened at first.

Sure there was a tiny spark as the second wire was connected but that is to be expected. The good news was that the 37.5ft coil of wire on the counter was warming up. I put the meter on the battery and confirmed it had dropped from 12 volts and was slowly draining down through the 11 volt range one one-hundredth or two at a time. After about 45 seconds or so the wire stopped getting any hotter and remained steady. As it seemed steady I decided to let it sit connected for about 10 minutes to see if any of the insulation was getting to hot and trying to burn.

After the ten minutes the insulation had not burst into flames nor had any other disasters occurred. The wire was still very warm but not so warm I couldn’t touch it with bare skin. This is what I was hoping for. Now it's time to attach the connectors and switch, but I’ll save that for part two of this write up which should be up in the coming days.

A preview of the final result.