Alternator issue

I’ve got a Sparx three phase alternator and the voltage seems to wander even when the rpm is constant.

Is this normal? The original Sparx regulator failed quite quickly and it was replaced by a Japanese Shindengen which are supposed to be good quality.

Oh yeah, it has an LED headlight and this only seems to happen when the headlight is on.

Does the voltage actually vary per a multimeter as opposed to the indicator? Can you temporarily install an incandescent headlight bulb to see what happens? Sometimes LED devices don't work/play well with other components/circuitry that weren't designed with LEDs in mind.

MexicoMike said:

Does the voltage actually vary per a multimeter as opposed to the indicator? Can you temporarily install an incandescent headlight bulb to see what happens? Sometimes LED devices don't work/play well with other components/circuitry that weren't designed with LEDs in mind.

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Good point. I'll test with a multimeter tomorrow.

It's a bit confusing.

The multimeter does't show any voltage drop when the battery gauge drops.

I also tried a halogen bulb instead of the LED headlight but that was inconclusive because it draws so much more current. I had to rev it much higher and I'm not sure it's a reasonable comparison.

Another thing which I think might be the place to look, is that the battery is only showing 11.9v. I'll charge the battery and see what happens.

pommie john said:

It's a bit confusing.

The multimeter does't show any voltage drop when the battery gauge drops.

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The multi meter must be connected at the same point in the system as the battery gauge. Then, if you are not seeing any voltage drop when the battery gauge drops, I would trust the MM, and assume the LED's are doing as MexicoMike suggests.

Slick