Home made heated vest

[dmmcd]

Most of you ChinaRiders are thrifty like me, so I thought this might interest you. I did this project back in 2008, and it is still working like a champ. I rode down to 10 deg F with this (and other gear) and it kept me warm.

So having a very basic understanding of electrical currents (I'm a mechanical engineer who always hated circuits) I decided to go ahead and make a heated vest. I understand the basic V=IR and P=IV and power is dissipated through heat energy. So more power gives more heat. I had no idea what power to shoot for, but hey, 55W sounds good as it is somewhat typical of heated gear. That leads to a resistance of 3 ohms for a 12 to 14 V system.

The wire I had is telephone wire, 26 gauge insulated. I measured the resistance of the wire and found that to get 3 ohms I needed 75 feet. The important thing is the resistance, whatever wire you use. Rather than mess with 75 feet of stitching, I doubled the wire over and twisted it up so I had about 37.5 feet to sew into a vest.

I took my vest liner out of my leather jacket and found the center of my wire and started with that at the top center of the back.



Since I doubled over the wire, both ends are at the same point. By starting in the middle, I hoped to get equal wire and equal heat on both sides. Using my wife's sewing machine (which she never uses) I figured out how to thread the dang thing and then figured out how to do a zig-zag stitch.



It isn't pretty, but I got all the wire in place. I kept the spacing of the wire wider apart in the back so that I could run it more densely in the front, where I thought (correctly) I would need more heat.



Then I needed a connection to the battery, and I already had a battery tender on there. The tender came with jumper clips that I never use, so I cut those clips off and used the connector from that and soldered it to the heating wire.



Then I tied a knot in it and hand stitched the heck out of it for some strain relief. That way when I forget to unplug it and just climb off the bike (which I have done), it won't tear apart the wires.



The first time I tried it out I left it in my jacket, then wore a thermal hoody under that, then my shirt. It didn't feel all that warm, my thin leather jacket dissipated the heat faster than it could get to me. So now I layer it on top of my shirt, then my thermal hoody, then a rain coat to keep the wind out, then my leather jacket. I feel like a sumo wrestler, but it works great, keeps me toasty warm. If the vest fit tighter on me, I probably wouldn't need the hoody, but I like all the heat I can get. At 25 deg F it is completely comfortable, even a bit warm.

So there you go. I haven't caught fire like my wife predicted. The leads on the bike has a 7.5 A fuse. This draws about 4 amps. I don't know what the charging capacity of Chinese bikes are, but the SV650 has about 100W to spare for components, and the vest doesn't drain the battery while the bike is running. [/img]

[FastDoc]

I am impressed with your work!

An electric vest and gloves are part of the secret to my ability to ride 11 months a year. Even in the summer, when travelling in the mountains, I will pack the electric gear. I'm a believer!

[Weldangrind]

Excellent! I appreciate that you took the time to do the math. I would have guessed that more heat in the back would be a benefit; thanks for clarifying that it's better in the front.

All I can think of when I see those devices is "controlled short." Of course when you think about it, any system on the bike is a controlled short.

What temp do you think the wire reaches? What temp is the wire rated for?

BTW, I get similar votes of "confidence" from my family.

[katoranger]

I like it. I could ride year round with a vest like that here.

[davidsonsgccc]

that is a really cool setup. im sure alot more cost effective than buying it.

[katoranger]

I think my elite would have enough extra juice to power a vest too.

[dmmcd]

Originally Posted by Weldangrind

Excellent! I appreciate that you took the time to do the math. I would have guessed that more heat in the back would be a benefit; thanks for clarifying that it's better in the front.

All I can think of when I see those devices is "controlled short." Of course when you think about it, any system on the bike is a controlled short.

What temp do you think the wire reaches? What temp is the wire rated for?

BTW, I get similar votes of "confidence" from my family.

The wind from riding hits the front of the jacket, thus transfers the heat away from the front. I almost always wear a backpack, so the back of the vest doesn't get the convection. That's why I wanted more heat in the front.

Calculating the temperature in the wire is a very complex undertaking, and it depends on many different factors, including ambient air temperature, convection currents, conduction through the vest, and involves solving differential equations.

Basically, depending on the outside air temp and how many layers I am wearing, it feels like it probably gets close to 100 deg F on the warmer days. I've never actually measured it.

[FastDoc]

Originally Posted by katoranger

I think my elite would have enough extra juice to power a vest too.

I'm sure you'd be fine. I've run an electric vest and gloves on every bike I've had in the past 20 years, including 200cc CB's and have never had a problem.

[katoranger]

A vest will be on my wish list then. About November when it is getting cold I can plug in.

[SpudRider]

You did an excellent job, DM! Thank you for sharing the excellent photographs detailing your creativity! I need a vest; however, I think I will probably buy a vest, since I lack a sewing machine, and the skills to use it.

Spud