When I made my heated jacket, the element was 25 feet of 30 AWG Belden Teflon coated hook-up wire. Since the rolls are 30 metres, most of the roll has been sitting on the shelf. It is difficult to determine the actual wire length required for a specific heating task because the wire changes in resistance value significantly when it is hot so guess-timate is required.
We guessed at 32 feet of wire (16 feet per side) to give about 25 - 30 Watts of heat per side which is what the Hein Gerlich grips on the ST have. Those grips will literally burn one's hands on high position so meet the criteria of having reserve capacity. Additional estimation issue is that one cannot always predict the charging system set point voltage because this can depend on load and temperature. The ST runs in the 14-14.4 volt range when ambient conditions are cool but can drop into the mid-13's volts when conditions are hot. Since one needs less grip heat when temperatures are 85 - 90 F, this works out well. (VBG)
We used the technique which worked well on dual sports which was to wrap the left bar end with hockey tape in order to insulate that bar end heater so as to even the heat output from side to side. Putting the heater onto the steel bar (aluminum is worse) will result in a toasty right hand and freezing cold left. This is the reason that many people have had better success with one-piece heated grips rather than a grip heater element under a regular grip. Since Suzie has new grips and I can make heaters, paying big $ for Hein Gerlichs seems unwarranted.
In order to terminate the wires with both ends to the inner end and avoid crossing the heating wires (concerned about concentrating heat and damaging insulation) we looped the wire in 1/2 and started two ends together at the inner end of the grip where the wire was secured by a wrap of plastic electrical tape. The wire "pair" was wrapped into a spaced spiral to the end of the grip where the end was secured by another wrap of plastic tape. Note* I have found that tight plastic tape anchors the ends without insulating as would hockey tape.
Note photo shows wire before wrapping by plastic tape in the outer end. The termination loop can be seen under my thumb.
Next, the wire was covered by a tightly pulled spiral wrap of single layer plastic electrical tape which started at the outer end. This wrap is necessary to prevent the wire from being displaced during installation of the rubber grip. The two termination wires can be seen at the other end, near the switch pod.
Here I made an error as the termination wires should have been made an additional 8" longer for the throttle side grip as it was necessary to splice on some additional lead wire. More on that later.
The throttle side requires some additional attention, depending on the design of the throttle sleeve because most throttle sleeves have some radial ridges in order to reduce the tendency of the grip to slip/turn on the plastic throttle sleeve. In the case of the GS the ridges simply required care in wrapping but some I have done required that the ridges be slotted by a triangular file.
One also needs be cautious in wrapping the throttle tube because stretching of the plastic tape because, over time, the constriction can crush the plastic sleeve. A warning is in order!
We connected each heater in turn to a 12 volt battery and monitored voltage and current.
Soapy water and the grips went back so the next problem was to connect wiring. The problem with connecting small hook-up wire to harness wire is avoiding flexing or tension which will break the wires !@#$%^!!!!
I have had success by wrapping the harness wires partially around the end of the grip and attaching by a wrap tie which we did on the left side. Brad had a much better idea for the throttle side. He suggested using a length of 1/8" nylon tubing to provide a semi-flexible conduit which conveys the 32 AWG wires but is practical to anchor to the inner end of the throttle tube. The two (should have been made longer originally as noted) wires were passed through the nylon tubing and anchored at either end by heat shrink. The wires were laid to overlap in the gap when the grip was rolled back a small amount and secured by another narrow wrap-tie. The nylon tube angles forward over the brake lever and evens out flex beautifully.
The heaters are connected through a SPST toggle switch for temporary testing. Power comes from the headlight fuse in the fuse box in order to have switched power for testing. I wanted to avoid installing a dedicated relay and wiring until it is confirmed. The headlight circuit is a useful supply in this case because the HID headlight conversion is supplied by its own fuse.
Here is a shot of the throttle side with lead nylon conduit:
can't get the image to load so will attach to next post.
When heated the grips draw 3.2 amps @ 13.7 volts = 44 Watts or 22 per side.
I'll report on how they work out later on. I suspect that they will need some means of reducing output but will decide on whether to construct & hide a pulse width modulator or simply use a series resistor with DPDT switch.
Norm
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