Curvy Stator Question

[TamSV]

Curvy SV. No engine mods. Various wiring changes inc my own front sub-loom, aftermarket lights (normal bulbs -no HID's) and clocks.

I got stranded with a dead battery last year. New battery fitted and the usual tests confirmed the reg-rec was overcharging. Stator output was OK - somewhere in the region of 60V AC at 5,000 RPM and was the same across all 3 phases. Stator continuity was 0.7ohms - a wee bit out of spec (0.2 to 0.55 ohms according to the manual) but all 3 readings were the same and no path to earth.

New SV shunt reg-rec fitted and getting good stable voltage at tickover and at 5,000 RPM. I also fitted a voltmeter into the headlight bucket to warn of any future problems.

That voltmeter is now telling me that everything is fine up to about 7k RPM at which point it goes a bit mental with the voltmeter needle bouncing back and forward off the stops. At 8,000 RPM and above it shows output voltage at the meter's maximum - something in excess of 20V.

I wonder if the stator output is too high and that's overcoming the reg-rec's capability to regulate voltage - I've no idea how likely or even possible that is.

My thoughts at the moment are I'm going to do the output test again with my multimeter but, instead of 5k RPM I'll need to do it bouncing off the rev limiter (neighbours should love that ). That will confirm, or not, what I'm seeing on the bike's own voltmeter.

I'll then test stator output in the same manner. Is there a maximum safe output that the stator shouldn't exceed?

I might be barking up the wrong tree entirely, of course, so any other thoughts are welcome.

[Sid Squid]

Very much doubt the problem is with the windings, sounds like regulator or perhaps connections - high revs vibration is making something connect less well than it should.

I know this stuff well, and of course I'm quite happy to be corrected, (learn something new everyday etc etc), but I don't see how a failure of the stator could cause over-voltage, of course a recheck of the winding and cabling resistances will inform of the insulation's condition, but any failure there would cause under, rather than over performance.

[TamSV]

Cheers Sid. If you think it's unlikely to be the stator that makes me happy.

I'll see what I can see tomorrow. It's certainly possible I've just been unlucky with two reg-recs.

[yorkie_chris]

Originally Posted by TamSV

I wonder if the stator output is too high and that's overcoming the reg-rec's capability to regulate voltage - I've no idea how likely or even possible that is.

No such thing really.

It will be another duff reg rec. Possibly a diode breaking down at higher voltage and letting AC through if it's going bouncing around mental.

[TamSV]

Thanks chaps. A clear gap in my knowledge here so I spent last night reading up on the workings of stator windings and reg-recs. As you say, any fault in the stator is most likely to lead to loss of voltage rather than a spike.

It was the fact that my last reg-rec was definitely overcharging and the new one seemed to be going the same way that led me to think something else was amiss further down the line.

Anyway, it all checked out today. Output voltage is still good. When the bike voltmeter was off the scale at high revs my multimeter on the battery was still happy.

I attached the multimeter to the bike's voltmeter terminals and tested again. Same result - voltmeter going daft but multimeter was showing normal voltage. The voltmeter I fitted is clearly haunted, probably by the ghost of Michael Faraday who is angered by my lack of electrical understanding.

It turns out the only problem on the bike is the thing that I fitted to warn me of problems on the bike.

I switched my multimeter to "irony" and got a very high reading.

[Sid Squid]

An actual LOL here!

[yorkie_chris]

Originally Posted by TamSV

I switched my multimeter to "irony" and got a very high reading.

Tea on screen moment