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Thread: SR400 heated handgrips

  1. #11
    Senior Member chunk's Avatar
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    My quick search says that the bikes output is 268 watts, about 20 amps and the grips need about 4 amps to function. I'm surprised there isn't enough headroom to run them, so as suggested you will need to trim some of the current draw by going with led's. Add up all the wattage of the bulbs now installed, add up the required wattage for all the led's and see if you can save an additional 4 amps, then the grips will be happy. I think it will be do-able. Led's really sip the current. Cheers.

  2. #12
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    Such awesome information. Thanks everyone

  3. #13
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    I just recently installed the same grips on mine. I've been able to run them with no problems on the lowest setting (which is all I've needed so far here in North Carolina), with the caveats that I turn them off when I'm stopped at a light and they're only used for about thirty minutes in the mornings before the battery gets a chance to recharge. If yours aren't able to do even that much, you might need a new battery.

  4. #14
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    Quote Originally Posted by brendan View Post
    I just recently installed the same grips on mine. I've been able to run them with no problems on the lowest setting (which is all I've needed so far here in North Carolina), with the caveats that I turn them off when I'm stopped at a light and they're only used for about thirty minutes in the mornings before the battery gets a chance to recharge. If yours aren't able to do even that much, you might need a new battery.
    Please, for greater comparative information, specify what brand of grip this is with.

  5. #15
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    Quote Originally Posted by Row1 View Post
    Please, for greater comparative information, specify what brand of grip this is with.
    Same as slinberg's. Oxford Heaterz.

  6. #16
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    Update: I wired a tiny voltmeter across the taillight circuit, and over the past three days I've been using it to conduct a sort of torture test of my SR400's electrics with the Oxford Heaterz heated grips. During that time I rode around just as usual, except that I constantly ran the grips at 100%. (This was very uncomfortable at times, but I did it anyway... for science.) I did not turn them off at stoplights, nor did I try to keep the engine speed higher than usual. My riding is a mix of around-town and 45-55 mph highway, typically going 15-30 minutes at a time. Note that I have not installed LEDs or made any other modifications that would reduce the electrical load. My battery is almost brand new, though.

    Over three days and fourteen rides in total, I checked the voltage after each ride with the main switch in the on position but everything else (engine, headlight, grips) off. The readings were almost always 12.4 or 12.5 volts, showing no sign of the gradual decline one would expect if the grips were drawing more power than the stator can provide.

    There were two exceptions, with readings of 12.1 and 12.2 volts. Both were after very short rides, around 10-15 minutes. One was all low speeds and stoplights through downtown, the other was mainly spent inching forward and stopping in a traffic jam.

    So that's great news. Based on these results, I'm confident that the stock FI SR400 electrics can support the Oxford Heaterz grips. If you do a ton of stop-and-go and idling at lights then you might not be able to run them at 100% all the time like I did. But at low speeds you probably don't need so much heat anyway. Only if it's so cold that you do need full power at low speeds will you have to install LEDs or otherwise expand the electrical capacity.

  7. #17
    FORUM SUPPORTER speedshop's Avatar
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    Quote Originally Posted by nbcarey View Post
    I believe the SR400 alternator is about 30A @ 12v DC.
    Wow! 30 amps!

    I doubt it.

    At best 12 amps at 5,000 RPM.

    You can't add batteries to avoid them being drained. You need output from the generator.

    What you might be able to do is to replace every other bulb on the bike with LEDs. Not the headlamp. Tail lamps and instrument bulbs are less obvious that they are not stock and much cheaper - they may give you back an amp or 2.

    Personally I wouldn't try running anything like heated clothing on a system an output of less than 25 amps and with a with a forced air cooled car type alternator.
    Last edited by speedshop; 11-21-2017 at 05:58 PM.

  8. #18
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    Per the service manual:

    AC magneto
    Standard output ... 14.0 V, 22.3 A @ 5000 r/min

  9. #19
    FORUM SUPPORTER speedshop's Avatar
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    Okay, so nearly a third less than 30 amps!! I've never run the modern systems, but the stator is an RD/TZR item, I've never seen one make that power yet. Mind you the EFi could be power hungry and they might have used magnets that are much stronger than before to get the extra power.

    22 amps though, what a drain on crankshaft power - the system will be on full load all the time (due to a shunt type regulator) - is fuel injection worth it!

    Early SRs with their 12 amp generators will be loosing significantly less power to their generators!
    Last edited by speedshop; 11-24-2017 at 04:19 PM.

  10. #20
    Senior Member oilyrover's Avatar
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    First person perspective... I run a Gerbings electric jacket liner and gloves on my 78 SR500 without any issue. Standard 10a fuse in the connection harness has never blown.

    From the Gerbings site it looks like the jacket pulls 6.4a and the gloves pull 1.1a per. So a total of 8.4a.

    I'm using a standard H4 bulb, standard indicator lights and tail/brake lights, LED turn signals. When it's really cold and I'm riding with both on Max i'll usually try and shut them off a few minutes before my destination. My thinking is that it will give the gen/alt a chance to rest/charge any shortage before shut-off. No idea if it helps at all but...

    Oilyrover

    FYI
    Last edited by oilyrover; 01-13-2018 at 09:50 AM.
    "A life without a few marks isn't much of a life"
    78 SR500 - 78 R80/7 - 83 R100RT - 88 GSX-R1100

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