Failing electronic regulator?

I just fitted a new Lucas branded 10amp stator from Feked. Checked voltage at idle with and without lights and seems ok. It needs 3500 rpm to maintain 12.6v on dip or high beam as expected. However I noticed a wildly fluctuating voltage on my meter after being connected for a few secs. It could be the meter of course but wondered if it was an indicator of a failing reg. Its the 25amp std aftermarket part from Paul Goff and is a few years old. Previous tests showed a steady reading rising and falling with rpm changes as expected. Any ideas?

Digital meter can be badly affected by the ignition, use an old analogue meter.

That could be it Kommando. I changed the caps for non suppressed since I last tested it. Ta, will investigate that.

Keith1069 said:

I just fitted a new Lucas branded 10amp stator from Feked. Checked voltage at idle with and without lights and seems ok. It needs 3500 rpm to maintain 12.6v on dip or high beam as expected.

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Interested to see where this post heads as I've noticed similar fluctuations recently with my 3 phase Sparks unit. I replaced the Sparks regulator with a podtronic but there are still fluctuations. (measured with analogue meter)

Keith1069 said:

I just fitted a new Lucas branded 10amp stator from Feked. Checked voltage at idle with and without lights and seems ok. It needs 3500 rpm to maintain 12.6v on dip or high beam as expected. However I noticed a wildly fluctuating voltage on my meter after being connected for a few secs. It could be the meter of course but wondered if it was an indicator of a failing reg. Its the 25amp std aftermarket part from Paul Goff and is a few years old. Previous tests showed a steady reading rising and falling with rpm changes as expected. Any ideas?

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10 Amps is a rather wimpy stator. You need a minimum of 13.7 volts with lights on, and preferably get it at 2500 rpm, unless you do mostly highway driving.

Stators are rated in Watts ... yours is likely 120 Watts. You may need a 180 - 200 Watt to get your voltage up.

The voltage should behave as you state; rise and fall with rpm. An intermittent open or short in your wiring might cause the fluctuations you see. A low resistance, but not a dead short could be holding down the voltage to 12.6. I would not bin the regulator just yet, but would isolate my load circuits and test for fluctuations and proper voltage.

Slick

Agreed it is a 'wimpy' little stator but enough for my needs. Yes the non resistor plug caps were the culprit for the erratic meter reading as Kommando suggested....thanks. Fitted the old 5000 ohm items and confirm that on a fully charged battery after 5 mins running the alternator maintains 13.3v with ign and lights (appx 100w)@ 3000rpm. With Main beam held on (total 160w) it dropped to 13.3v @ 3000rpm but 13.9v @ 4000 rpm. Max voltage was 14.1v @ 4000rpm (160w) or 1500rpm (30w ign only).
It just remains to be seen if it survives any better than the Sparx. Since it looks to be the same insulation colour and very similar finish I'm guessing its the same part but with Lucas brand moulded in place of Sparx.