REPAIRING YOUR ELECTRIC VEST
From: Brian Curry <email@example.com>
Date: Sun, 04 Apr 1999 23:14:48
All of us have problems now and then ... Even me. I found one of the circuits in my vest open just before leaving for Daytona. The original repair post grew out of that. Since that post, I have gotten a few private replies with additional info. Based on the additional info, I have revised the original post.
The various electric vest manufacturers have different warrantee lengths. I believe they are as follows: Aerostich - 2 year warranty, Eclipse - 5 year graduated warranty (pro-rated like a car battery), Gerbing - Lifetime guarantee on electrics, Widder - 1 year. (Widder apparently does courtesy warrantee work after 1 year. Pat Widder says: "Our main support is to the end user! And this is regardless of how old the gear is.") If your vest fails/breaks under warranty you are in good shape. If so, you would not have to repair your own vest. You would be lucky. Except if you find it is broken two days before you are leaving for Daytona. Then, even with Fed-Ex, you might want to repair it yourself. You would be unlucky. This post describes how I repaired my Gerbing electric vest, some other electric garment/apparel information I found, and some recommendations. Remember, I was successful here, with the skills and knowledge I have. Your skills, knowledge and results may be different. Pat Widder asked me to note that Widder Enterprises do not recommend any of this.
I have a Gerbing vest. It uses four separate heating circuits. I found one of the back panel circuits had lost its connection to the power supply harness. (More later on how I found this, and how you can check for problems before you detect it as NO HEAT. :(:( ) To make a repair, I strongly suggest either knowing how to use a sewing machine, or knowing someone that knows how to use one. (Get them to do the resewing after you fix the wiring.) Sewing the vest back up by hand, would be a PITA. I used a seam ripper to open the seam on the bottom of the vest. Then I turned the vest inside out to work on it.
The wire in the Gerbing vest is not, IMO, "really wire". (The Eclipse vest uses the same type of wire, and I suspect Widder vests do also.) It is a very, very, very, very fine copper wire wrapped around a synthetic fiber string cord, and then coated with plastic insulation. About 20 years ago, I ground through this heating wire on one of my vests. (Crashing sux.) Rather than trying to solder it, I used a crimp connector to rejoin the ends. When I repaired two Eclipse vests for __T_E_R_R_Y___M_i_a_m_i___©™, I also used crimp connectors. However, for this repair, I had an example. It looked like Gerbing soldered the vest wire to the power supply harness and then put a bit of heat shrink over it. If they could do it, it was likely I could too. :) I was at least willing to try. Cold is bad. Heat is good. More heat is better than less heat.
I located the heating wire adrift from the power supply wiring harness. I carefully removed the insulation around the "wire core" and wrapped the so called wire around the power supply harness wire. (IMO, a "wire stripper" would not work well. I used a sharp pocket knife to take slivers of the insulation off, exposing the wire around the core. Then I worked the rest of the insulation off. Pat Widder reports the insulation on the wire he uses is particularly difficult to remove.) Then I put the soldering iron tip to it, added solder, and watched what happened. It worked better than I thought. The soldering iron heat melted the thread core, and the solder made the connection to the power supply harness. I spooked a bit when I saw the thread core melting, but it worked out OK. It was solid. I put some heat shrink tubing over it, and was ready to go electrically. :):) The heat shrink tubing is important. It keeps stress off the really, really, really, really fine wire connection to the rather solid harness wire. That connection will not take stress. This also showed that at least some of the vest manufacturers do not use Nichrome wire for heating. Nichrome is virtually impossible to solder to. (Caution: I shortened the circuit by maybe 1/2". Remove absolutely no more wire than necessary. Shortening lowers the resistance, increases the current, and raises the wire operating temperature.)
Eclipse vest "wire" thread cores don't melt. They likely use fiberglass as a core. One could still twist, solder and heat shrink I suspect. It likely would not look nice. But could work fine. This also shows that probably there are a number of "heating" wire suppliers, or they will make it to what ever specification heated gear manufacturer wants.
I found that, generally, the edges of the nylon cloth in the vest had not been heat sealed, and they were unraveling. This is not a good thing. I heat sealed them before I turned it rightside out, and sewed the lower seam up again.
Gerbing vest opened for repair
Now for some discussion:
Powering the vest heating circuits. What Gerbing does is bring in the power lead. (Nice and heavy.) Then they have a master splice that has two small zip cord (connectors) leads to the heating panels on that side, and one heavy set of leads (red and black, but not as heavy as the master leads) that go to the heating panels on the other side. This ends in a splice set that has two zip cord leads to the two panels on that side. The wire keeps getting smaller on the run. This power supply harness can get twisted around, pressing the vest against you and generating a hot spot or just generally being irritating. The harness can be kind of "trained" into the proper position, by mushing the harness low along the bottom of the vest. Based on my after repair experience, do as much arranging and training as possible before you resew the vest. It is easier than afterwards. DAHIK. But if you have a vest hot spot, palpitate it, and see if you can rearrange it so that it is not hot against you.
I have had three, actually four, vests apart now. I took apart two Eclipses for __T_E_R_R_Y___M_i_a_m_i___©™, this Gerbing, and I partially took apart, the one I ground the wire apart which I think was a Gerbing too, but not identified as such. It was 20 years ago and I don't have it now. All of them used the same general type of "wire". This is real fine copper wire wrapped around a string core. If you are trying to make a vest on your own, you might try finding an electric blanket being given away or dead. I think the wire in them is the same basic stuff. One caution. The wire apparently comes in different gauges. So, electric blanket stuff might be too heavy, or too light a "gauge". You are on your own voyage of discovery using electric blanket wire.
Heat Shrink was used for insulation over all the splices. Over the master splice it was a blind heat shrink cap setup. Over the sub splices it is "normal" heat shrink and has an open end. And not the stuff with sealer on the inside, but simple heat shrink tubing.
As I noted my Gerbing vest had four parallel circuits. One double circuit panel in the back. And a single circuit panel in each side on the front.
Since one of the circuits was disconnected I took some electrical measurements. One back panel circuit measures 14 ohms. One back panel paralleled by two front panels is measures 3.5 ohms. (Measured from the power connection.) Doing the math, the paralleled front panels resistance, paralleled to the 14 ohm back panel is 4.666 ohms. The combined resistance of both front panels is 4.666 ohms. Thus each front panel has to be 9.333 ohms.
So, there is more heat from the front panels circuits than from the rear panel circuits. (The circuit resistance is lower, so there is a greater current and thus more power.)
The calculated paralleled resistance of all four circuits is 2.79 ohms. After connecting all four circuits the resistance, measured, was 2.75 ohms.
Looks like good data to me. Editor's Note: And as Brian often says ... "without data it is just another opinion" :)
I strongly suggest measuring the resistance of your electrically heated garment/apparel NOW. They vary depending on the manufacturer, the size and just what the apparel is. The resistance of a jacket(liner) is lower than a vest. I don't know about gloves or socks. Generally the greater the power, the lower the resistance. Record it. Measure it before each long trip or periodically. Measuring electrically heated apparel resistance is not easy. The resistance is pretty dog gone low. Measuring low resistance is very prone to error and variation using typical consumer grade meters. The meter lead resistance is, or can be, close to the vest resistance. How hard you press the leads against the electrical connections can affect the reading. Some recommendations: Use the same meter each time. Not the same type meter, THE SAME METER. Press the leads firmly against each other, and adjust the meter for a zero reading. Or if a non-adjustable digital meter, note the lead resistance. Then firmly press the leads to the connector conductors. Record the reading. Do it several times. Make sure it is consistent/repeatable. If necessary average the readings, and subtract the lead resistance if you could not zero it out. Then write down that consistent, reliable, average reading.
If the resistance starts increasing, or significantly increases, you are in the process of losing, or have lost one of the circuits in your vest. (As noted the Gerbing vest uses four paralleled circuits. The Eclipse vest uses two. I think the Widder vest uses two also. So, loss of one is not mission critical. You have not lost all heat. But it is better to find and fix the cause, before you loose all the circuits.) I found which circuit I lost by holding the vest up to a bright light, following the wiring, and noting that I had a "free end" that was not connected to anything. The ability to 'see through' the vest varies. Some you can, and some it is damn difficult to. I don't know how many internal heating circuits Aerostich gear uses.
A better method, but it takes a high range ammeter, which few people have, and a power supply (for constant repeatable applied voltage), is to measure the apparel current after it stabilizes. If the current is lower than the first, baseline, measurement something is changing for the worst. The apparel power is dropping. Find out what is causing it.
If you cannot see or find a break when you open the vest up exposing the wiring, your problem has increased. This indicates that the heating wire has broken. :(:( You can probe the wire with a pin/needle to find where the break is. However, Pat Widder noted, probing may find a good wire, but the needle may possibly damage the good wire, somewhere other than where it broke. So it is good when you are checking, but will be failing sometime thereafter. This is a caution. After you find the break, I would cut the break out, and then solder a jumper, as noted here, between the ends.
Ron Beckley reported another method to find the break. You might not have to slice the whole bottom of the vest open. Ron applied/connected a tone generator to one of the power connections. Then using a tone receiver, traced the wire path. The break was where the tone stopped. He traced the wire from the other end to confirm the break and make sure there were not two. Tone generators and receivers are used by telephone repairman, electricians, and computer network maintainers. Maybe you can borrow one, especially if you only need it once. I have seen something similar in catalog for about US$30. The vest outer covering can then be sliced open, (He put a 2 inch slice in it.) the break repaired, and the slice sewn up.
Remove as little of the heating wire as possible. DON'T JUMPER LARGE LENGTHS OF IT. Each bit of heating wire you remove reduces that circuit resistance. This increases the current. Increased current means increased heat. If the heat gets high enough, it can cause discomfort, or startle you if a section that has been in the air suddenly is pressed against you. Use caution in shortening the heating circuits. If you have a baseline resistance or current measurement, do a comparison of the before and after repair values. It will give you some idea how much of a change you have made.
Now remembering most vests are rated at ~40W, I thought they might depend on the wire getting hot enough to increase the resistance reducing the current. This is the case. I put my Gerbing vest on a 13.75VDC power supply and measured the current. It started at 4.22A and stabilized at 3.54A. Putting a Gerbing jacket liner on the power supply, it started at 7.74A and stabilized at 6.53A. Checking a second Gerbing jacket liner, it started at 7.48A and stabilized at 6.54A This was with no body/person, inside the vest or liner. It took about 20-40 minutes to stabilize. The stabilized current reading translates to 48.5W for the Gerbing vest and 89.5/89.9W for the Gerbing jacket liner at the power supply 13.75VDC voltage. With ~90W the Gerbing jacket liner puts a lot more heat into you. It is a good thing that it has additional circuits in the arms. Taking some crude temperature measurements with the vest and jacket laying on the floor with no body/person in them and stable current, there are some indications of where the heat is being applied to the body. I measured the vest body area at ~172 degrees F, the jacket liner body area at ~222 degrees F on one jacket (insulated), and 130 degrees F on the other jacket liner (uninsulated) and the insulated jacket liner arms ~130 degrees F. Now before someone runs screaming about "TOO HOT!!!" remember there was no body in the vest. Two heating surfaces were towards each other. The measurement technique was crude. There were no "standard" conditions. So calm down and stay warm.
If you are comparing vests based on wattage, use caution or be skeptical. Most of the vendors don't report the voltage or method used determining vest power. The voltage makes a big difference. Any vest at 13.7 volts (a reasonable operating voltage) will produce 18% more power, than at 12.6 volts (normal battery voltage.) even though the voltage is only 8% greater. So, ask what voltage was used if you are comparing power levels. Likewise, if they measured resistance and calculated power, due to the wire resistance increasing as it heats up, the cold resistance was lower than the operating, hot, resistance. You would get less heat, when the vest is in use and warm, than what was stated/calculated. So, if you are comparing wattage, and they are close, and you really want to know, ask how they determined that wattage and what the test conditions or assumptions were.
Also use care in selecting the vest power cords. Larger wires are better. And the shorter the wires are, the better. I tried using the Aerostich coil cord with the trick light on it. The cord got HOT from the current through it. With power directly on the vest, the current stabilized at 6.54A. Using the coil cord, current stabilized at 6.05A and a vest terminal voltage of 13.46V. This calculates to 10% less heat out of the vest. I consider that significant. (The cord was dissipating 1.5W.) Pat Widder says his coil cord is 16 gauge wire.
I did find some strange data from the Gerbing vest. The back panel circuits are 14 ohms each. This is cold measured data. The length was 96" for one circuit. The front circuits are 9.333 ohms and 126-7" long. (I did my best measuring the front circuit lengths twice without taking them out.) They must change the wire gauge in each circuit. The shorter rear circuits have higher resistance than the longer front circuits. So, it seems the front circuits put out more heat, but it might be spread out more than on the rear, making it seem like less. I am not sure if I can, or cannot feel a difference in heat.
Likewise, when I turn on the Gerbing jacket liner, I feel the heat in the arms first, but they don't get too warm when the heat is stable. Even though the temperature measurements say I should feel the body area being much warmer, I don't. I speculate that this may be due to less body fat on the arms than the torso area. The Gerbing jacket liner seems to have cool unheated areas on the side. Comparing how many vertical wire runs there are, and their height, it seems the jacket liner has fewer but longer runs than the vest does. So, it might have cool areas on the side.
Here is some data for consideration. While considering this, remember that the exact heating wire length varies depending on the size of the vest. YWLMV But, an Eclipse vest has ~24 ft of heating wire, a Widder vest has ~27 ft of heating wire and a Gerbing vest ~36 ft. The Gerbing jacket liner had ~40 ft of heating wire in the body area and ~12.5 additional feet of heating wire in the arms.
Now, why would you care how much or how long the wire is? Think on this. Assume each vest or other garment/apparel has the same power output/input. The shorter the wire, the more power per inch of wire length. With a constant vest power, a shorter heating wire length means more power per unit length and the wire is hotter. So, you wanted heat right? Well, yes, but not too much. There is a balancing act going on here. A longer wire has more "effective area". To transfer a constant amount of heat, the larger the area, the lower the required temperature difference. (If you are trimming the heating wire length for a repair, it is a double whammy. The resistance will decrease, the current will increase, the power will increase, and the wire temp will increase. So use caution when jumpering, or shortening the heating circuits.) You want the heat close to you so you get/stay warm, and you don't lose the warmth to the heat sucking outdoors. If the wire is too hot, you get branded. :(:( Most people get upset seeing red marks trail over their body. Women can become very upset with hot wires pressing against the wrong places...
You can be warmed by conduction, radiation or convection. Touch a hot pot on a stove and conduction burns you. Hold a red hot rod close to your skin, and radiated heat will burn you. Stick your arm above a chimney, and convection will burn you. A warm wire can be touching you allowing conduction of heat. Even if it is not touching you, radiation from the warm wire will warm you just not quite as sensibly (well). A hot wire should be some distance away from you. Then radiated heat from the wire warms you. You don't want it conducting to you. (For an extreme example, think of an electric floor heater with the glowing wires. Some distance away from you it feels warm. Touching the glowing wires, you feel pain. I don't think any vests have glowing wires. The example is for purposes of illustrating radiated heat.) Electric apparel is not designed to warm by convection to the best of my knowledge. Depending on how the manufacturer constructs the vest, the wire might be separated from you by the thickness of the cloth shell and whatever you are wearing, or there might be a insulating layer between you and the wire to "spread" the heat. While it insulates the warm/hot heating wire from you, it probably allows some of the heat to escape outward. And remember you want the heat close to you, or being applied to / conducted to / and lastly IMO radiated at you. For a constant wattage, more wire means lower peak wire temperature, allowing the wire to be closer to you without getting too hot. :):) The optimum setup would be a warm constant temperature surface with a low peak temperature, but a high wattage output. (Equivalent to wires running side by side up and down in the heating area.) With a large area (very, very long wire length), the wire temperature would be low, allowing with a close fit, excellent conductive as well as radiative warming/heating. While an individual making their own electric apparel might take the time and effort to use very long lengths of wire, the economics for a volume manufacturer would not be good. Now if someone figured out a way to do it ... :):) We can always dream.
More heat is good. I used Anton's Gerbing jacket liner with ~90W output on the way back from Daytona. With the additional heating wires in the arms, the extra power is spread over an additional surface area, the arms. Remember what I said above about high power, short wire lengths, and greater area. Extra heat is good. :):) Recently I tried Charlene Bare's uninsulated jacket liner. I thought the front circuits were dead. :(:( Testing some more I found they were not. What I think was happening, was the fit was not good. It was not close to me in the front, and being uninsulated it was difficult to feel the heat. Fit is important! So, IMO, get as much power as you can, (you might be alternator limited), tucked or applied as close to your body surface as you can, with as much heating surface as you can, at as low a heating element temperature as you can. (The last two are related.)
I would like to thank Anton Largidier, and Charlene Bare for loan of Gerbing jacket liners for use and testing purposes. Anton also lent me the Tripplet Ammeter used for the current measurements. A copy of this revision was sent to the four active US electric vest manufacturers I know of. Replies were received from two of them, Widder and Aerostich. I thank both of them for taking the time to review and reply to the post.
If you feel really daring, are not brain dead, are ready to look hazards right in the eye and go forward, are willing to take responsibility for your own actions, in other words don't need someone to make sure that you are not hurt, you might make your own heated apparel. (Note that Pat Widder thinks you should not work on electrically heated clothing on your own.) Check these sites for info on how to 'heat your own'.
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