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xvs650 Generator Charging Capacity” or “Generator Output”

Discussion in 'Modifications and Projects' at netrider.net.au started by ashrose, Jul 10, 2015.

  1. hi guys, its been awhile but im back again.
    hope everyone is well and not getting to cold through these "cooler days".

    im looking for some advice as allways.
    i am wanting to put some LED lights on my bike for safety.
    what im looking for is how many watts the stator puts out. i've spent the last 2 days looking through google
    to try and find out but cant find a solid answer.
    what i have found says between 205 watts to 295 watts ????? .
    the only xtrass i have is oxford heated hand grips. (48 watts- 4amps aprox)
    the lights i have are 2 x 18Watts and im wondering if i can run them ????

    can anyone help out.
    thanks in advance
  2. Electrical output is a bit of a rubbery figure because it will change depending on the RPM of the bike. Various automotive standards give two test speeds and the output at each of those speeds.

    My understanding is the standard load of the bike is:173 watts
    Your heated grips brings it up to 221 watts. At cruise speed the bike is probably generating 275watts and at stop start type riding about 230watts. So your margins are small, the lights would bring your load up to 257watts.

    So if you use the lights running at cruising speed you are probably OK, if your riding with the lights is slow speed or stop start you will be draining your battery.

    The above is based on the 173watt standard load taken from the site linked, it may be better to measure your load if you can. Hope that helps.
  3. Here's the output of a Bosch car alternator, revs along the bottom, amps on the vertical scale. At 1,500 rpm (idling) it puts out zero!
    Al waffle time...

    If you don't have a digital voltmeter, get a cheapy from an auto store. While you are there, maybe buy a cheap 35W halogen headlight globe - that's about the same as the LEDs you want.

    Warm up the bike so it's not using the fast idle. Put the meter directly across the battery terminal. Twist the throttle to 4,000 rpm or so and you should see the voltage settle at around 13.8V, that's what needed to recharge the battery in a reasonable time after the heavy drain of starting.

    Let it settle back to idle, if you get above 12V then that's ok. The battery isn't being recharged and is probably being slowly drained, but it's not going to go flat for some time.

    If the voltage is down below 11.5V, the battery is providing all the power to run the bike and is going to go flat soon.

    O.K. here's the test to see if you can add more load. Temporarily wire up the 35W halogen and run the bike at idle. If you get below 12.0V you can't run it at idle for too long.

    But... all is not lost. I put a little knick-knack digital clock on my bike that happened to have a voltmeter too. Sitting at the lights with my foot on the brake and the upgraded to 60W halogen headlight, I was getting 11.5V! The meter was wired up to the back of the lights - not the battery. Bit of investigation showed that the voltage drop across the contacts of the "run" relay was 0.5 to 1.5V, so the battery voltage was a bit higher around 12V but still in discharge zone when idling. Although commuting 5 days a week through a dozen sets of lights for 2 years I never had a flat battery, so the time spent at speed was enough to keep the battery charged.

    However I was at the limit. One stinking hot summer day when I was too knackered to filter and I was sitting in stop-start crawling traffic with the radiator fan kicking in and out for around 15 minutes. Noticed the engine warning light come on. WT? glanced at the voltmeter, saw 9.6V just before the engine stopped. Dead flat battery - roll start needed.

    If you are on the limit & you have an easily accesible switch for the heated grips - turn them off when idling for any period?
    • Like Like x 1
  4. thanks Al-cam
    i've got a voltmetre so seems like an easy check.
    will do it after the weekend (gota work) and let everyone know how it goes.

    thats the sort of thing i was looking for Cjvfr thank you
  5.  Top
    • Like Like x 1
  6. That 3500RPM is one of the standard SAE test revs I think. The bike cruise RPM is higher than that. Nevertheless because the information is a little conflicting I would go through Al_CamAl_Cam 's above procedure. It will give you a better clue.
    • Like Like x 1