Electric Clothes Info

As I mentioned on my bike page, I did the electronic design of the HEAT-TROLLER electric clothing controller. In the process I learned some things about electric clothes that may interest you.

A Range of Watts

There seem to be two main groups of electric vests. The Aerostitch, Eclipse, and Widder vests all make about 45 Watts of heat, and they all include insulation to trap the heat. The Gerbing jacket liners (which include heated sleeves), on the other hand, make about 80 Watts of heat, and have models with or without extra insulation.

What difference do these watts make when you're wearing one of these? The 45-Watt vests warm up slowly. When I turn on my Eclipse vest, it may be five minutes before I begin to feel the warmth. The downside of this amount of heat is that in cold weather it may not be enough to keep you warm. In moderate weather, the upside is that you don't have to turn the switch on or off very often. In contrast, a Gerbing liner feels warm almost immediately and can keep you warm in really cold weather. The downside is that in moderate weather, you have to turn it off and on frequently to maintain a comfortable temperature.

Keeping Your Hands Warm

To keep my hands warm I've tried electric glove liners and heated grips. I dislike electric gloves -- they keep my hands warm but they don't have other features I want (like reinforced palms, padding, and Kevlar). I wanted to wear my favorite gloves most of the time and save my winter gauntlets for the coldest weather. The first thing I tried was heated grips. I don't like the hard rubber heated grips, so I got a set of Farnum heated grip pads (available from Sport Touring Accessories) which wrap around my foam grips and attach with hook-and-loop fasteners. I wired plugs to the pads and sockets to the harness, then installed the harness and wired it to my HEAT-TROLLER. These pads really get warm! They keep my palms quite warm, but the back of my hands stayed cold.

I'm currently using a pair of electric glove liners. I got them from my friend Mike, who got them from a friend in Europe. They come from Japan, and Mike would like to import them but it appears the manufacturer isn't interested in selling to the US. This is unfortunate; I think they would be a popular product. They were apparently designed for golfers and were meant to be powered by 12 volt batteries. On a bike with a 14 volt electrical system they get very warm very quickly. I put a harness in my jacket which connects the liners in parallel with my Eclipse vest and control it all with the knob at my left grip. This is my present system for fending off the cold.

Control Needs

A controller allows you to adjust the amount of heat your electric clothes generate. The simplest form of control is to plug and unplug the power cable, but this can be tricky while riding a bike. The next controller type is an on/off switch. This is much easier to control than a plug, but with a high-wattage vest or gloves, you may have to switch it a lot. The next type is a duty-cycle controller. These controllers range from strictly mechanical (bimetal switch) through electromechanical (electronic timer and mechanical relay) to all electronic. This type of controller lets you adjust the percent of time the electric clothes are on during one controller cycle, and so regulates the amount of heat generated. The controller cycle times range from about a second for the electronic type to perhaps several minutes for the mechanical type. If you use a long-cycle-time controller with high wattage clothes, you can feel the clothing heat up and cool off as the controller cycles. For example, if a controller with a one minute cycle time is turned halfway on, it will be on for 30 seconds and off for 30 seconds. During the 30 seconds of 'on' time the clothes will generate full heat, and during the 30 seconds of 'off' time they will cool down. An electronic controller, with its much shorter cycle time, generates a much more even heat -- the clothes don't have much time to heat up or cool down during a cycle.

Note that all these controller types are 'open-loop' -- they don't control temperature, they control the amount of heat generated. This is very much like the heater controls in a car. So why don't electric clothes (or most cars, for that matter) have thermostats that let you set a desired temperature? Because they wouldn't work any better than an open loop controller.

Why Thermostats Won't Work On A Bike

A true thermostat would let the wearer set the desired temperature, then the controller would maintain that temperature. Why wouldn't this work on a bike? Because a rider doesn't want a constant temperature. While a certain temperature may feel good in one set of conditions (air temperature, wind, and sun or shade), when these conditions change that temperature could feel too hot or too cold. Just because a temperature sensor somewhere in your vest is at the desired temperature doesn't mean you wouldn't want more heat if a crosswind cools your arms, or less heat if the sun warms your back. I've tested thermostated systems as part of the HEAT-TROLLER project. I concluded that since they require a temperature sensor, they need just as much fiddling as an open-loop system, and since they don't feel any better, there's no reason to use them. An easy-to-adjust open-loop system works just as well, so I mounted my control where it's easy to reach.

How To Get The Most Heat From Your Gear

The basic rule is to maximize the wire gauge and minimize the number of connectors between the battery and the vest. Some vests use 22 gauge wire (as much as six feet of it in some coil cords) and many connectors. Some vests use connectors which aren't rated for power, but are rather audio signal connectors. The result of all this small gauge wire and many connectors is significant voltage drop in the power wiring, resulting in less heat from the vest.

If you'd like to compare the losses produced by different harnesses, this page outlines a test procedure.

Eighteen gauge wire seems a good compromise between flexibility and power loss, while using connectors rated at 15 amps should minimize connector losses. The Safco-style connectors (the type used by Eclipse and Gerbing) can handle the current, but they take two hands to plug and unplug. The BMW-style connector can also handle the current and is easy to use one-handed.

Last updated 30 Oct 1997