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Thread: Heated grip resistor

  1. #1
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    Heated grip resistor

    I have aftermarket heated hand grips on my K75S and the resistor for the low heat burned out. There is no marking on it to tell the size. Does any one know what size to ask for at Radio Shack? Thank you
    Rebel

  2. #2
    I'm guessing the resistor you want is switched in to reduce current through the heaters.

    Measure the heaters and match that resistance in the one you buy to divide the power evenly between the resistor and the grip heaters. You'll need a power resistor, probably 20-25 Watts. It's going to get hot.

    If this was my bike I'd use a PWM controller like a heattroller to infinitely vary the heat with about 1% loss. Doesn't get hot.

    If you are handy with a soldering iron you can build one. If you need a schematic let me know.
    Mike Marr
    1978 Yamaha XS750 (Needs rings), 1996 BMW R1100RS, 2004 Honda CRF230F

  3. #3
    K Bikes Complex by Choice cjack's Avatar
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    Quote Originally Posted by bmwrebel View Post
    I have aftermarket heated hand grips on my K75S and the resistor for the low heat burned out. There is no marking on it to tell the size. Does any one know what size to ask for at Radio Shack? Thank you
    The stock grips were 8 ohms each, in parallel which makes 4. Then the dropping resistance wire harness (it's a neat way to do it, even for aftermarket heated grips) is 2 ohms. Be sure to fuse the circuit at no more than 4 amps in case a grip shorts because the 2 ohms would be across the whole power supply in that case (ie, too much).

    So at 13 volts, the power in the grips (two of them) is 42.25 watts. That's 21.12 watts each. With the 2 ohm dropping resistor in series, the power is 9.39 watts each. That comes out about right for the heat HI/LO. The 2 ohm resistor then when on LO heat is also dissipating just under 10 watts. That needs to be on a heatsink or use BMW's resistance wire harness.
    R1200GS LC Rallye
    Jack Hawley MOA and RA #224, KE9UW ("Chuck")

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