Advice on GS500 with electrical problem please (long story)

Discussion in 'Australian Motorcycles' started by David, May 3, 2009.

  1. David

    David Guest

    I replaced the battery in my wife's GS500 about 4 months ago, as it was
    becoming difficult to start, only cranking over 2 or 3 times before the
    battery was too low. As the battery was around 5 years old, this seemed
    to be the most likely cause.

    The bike is only ridden rarely, maybe once every 4 to 6 weeks, and after
    fitting the new battery we found that each time she went to use the
    bike, the battery was dead, and we would have to jump start the bike.

    Our assumption is that the aftermarket heated-grip controller, which is
    meant to turn off the grips when the engine is stopped, may have been
    continuing to draw current, and flatten the battery.

    I have recently bought and started to use a battery charger, to try to
    keep the battery topped-up when the bike is idle. This weekend when we
    went to start the bike, it would not turn over, and the dash and
    headlights were very dim. The battery charger however was indicating
    that the battery was charged, and a voltmeter showed around 12.4 volts.

    I jump started the bike from the car, then detached the jumper leads.
    At idle the voltage across the bike battery was just over 12 volts.
    When I revved the engine it fell to less than 9 volts.

    I think we may have 2 problems here.
    1. A stuffed battery because we let it go completely flat when it was
    first fitted, and
    2. Something wrong with the alternator/regulator on the bike, so that it
    is not charging the battery, as I expect the voltage on the battery
    should rise when the bike is revved from idle, not fall.

    Any thoughts or suggestions please of what I could try, before I resort
    to taking it to the local bike shop.

    David
     
    David, May 3, 2009
    #1
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  2. David

    Knobdoodle Guest

    What year GS500? Does it have brushes in the alternator?
    If not then there's not a lot you can do except check all connections;
    especially the battery, engine and regulator earths... and then start
    replacing bits. (Regulator/rectifier first)
    Good luck,
    Clem
     
    Knobdoodle, May 3, 2009
    #2
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  3. David

    atec 7 7 Guest

    Assuming it's a normal alternator I would check the rectifier pack or
    alternator has not dropped a phase , usually they drop a diode or two so
    checking in and out with a meter will at least indicate what's going on
    , you really need a manual or a savy friend .
     
    atec 7 7, May 3, 2009
    #3

  4. You're spot on with the suspicion of stuffed charging system. Voltmeter
    should read between 12.5 and say 14 volts after 3k or so RPM however a dead
    battery can cause all sorts of dodgy readings when trying to trace a
    charging system fault.

    Remove or disconnect the battery then connect another serviceable battery,
    perhaps a car battery via jumper leads, and perform the voltmeter test
    again. It's likely that the voltage will remain at 12 volts indicating no
    charge. If so then you've got to test AC volts from the alternator then DC
    volts from the Reg/Rec If you're not clued up it's probably a job for an
    auto electrician familiar with bikes. If by chance the voltmeter test
    reads OK then replace the battery with a gel type. Replace it with a gel
    type in any case. They can handle extended periods of inactivity much
    better than the wet type. And buy a decent trickle charger.

    Last test should be with a charged battery and an ampmeter connecter between
    the battery negitive and earth to test for any current flow when the bike is
    switched off.

    It's also good practice to disconnect the negitive if the bike isn't being
    used for extended periods however connecting a trickle charger negates the
    need for this. Just good practice.

    Capt. A. L.
     
    Capt.about_lunchtime, May 3, 2009
    #4
  5. Notwithstanding the other sensible advice already offered, and
    acknowledging that I know squat about electrics, nevertheless: the
    battery discharging despite the trickle charger implies either a stuffed
    battery (preferably) or a leak of some sort - you can test this by
    pulling the battery out and trickle charging it; the voltage drop when
    the revs are raised MAY indicate a stuffed reg/rec, but it may be an
    artefact of the voltmeter and the surface voltage; and there is no
    better way to bring motorcycle electrical problems to the fore than to
    fit heated grips, because they are almost never fitted via a relay
    through the ignition switch, but rather are wired direct = prime source
    of earth leakage.

    You didn't say how old the bike was. If you can afford it, replace the
    reg/rec (not very expensive, about the price of a shop fitted battery),
    replace the battery (preferably not with something made in the PRC) and
    throw away the heated grips (on a bike that gets used once in 4 - 6
    weeks, heated grips are silly).

    You could also ride it a little more often. Internal combustion motors
    are not designed to be idle for weeks. When you park your daily drive in
    the garage overnight quite a lot of oil remains coating critical parts
    the next morning. 6 weeks later there's nothing there, and you can add
    10000km worth of wear in the first few seconds after starting the motor.
     
    Andrew McKenna, May 4, 2009
    #5
  6. David

    x.x Guest

    That is pretty cluey 4 sum 1 that reckons they no nothing bout leccy,
    respect
     
    x.x, May 4, 2009
    #6
  7. David

    David Guest

    Thanks to all for the advice.

    I tested the bike with it's battery removed, and with jumper-leads
    across to another bike, and the voltage on that battery showed the
    expected behaviour (ie >13.5 vols at idle, and >14 volts with a few revs).

    So I have replaced the battery, and the bike is now on a trickle charger
    when not in use.

    The heated-grips are currently disconnected, until I install a relay to
    ensure they are only drawing current when the ignition is on.

    Thanks again for the advice.
    David
     
    David, May 10, 2009
    #7
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