Generator Light

[KFH]

I have an intermittent fault with the gen light flashing. Driving during the day no problem occurs. I can go out to a meeting of a night with the lights on and all is well.  After the meeting the gen light will sometimes flash on and off at a rate 2-3 seconds apart.  It is rev related.  Low revs there is no problem but happens at about 20mph and above in second gear and the same equivalent speed and above in top gear.

I initially cleaned the cut out contacts even though they appeared clean.  Then changed the regulator with the same results.  Pulled the generator off found the brushes not sticking, clean commutator and well undercut. The funny part is that sometimes the flashing can be cured by turning the lights on and off. It often cures itself.  All charging voltages are fine.

On the odd occasion the gen light will come on hard when the ignition is turned off to stop the engine. Restarting the engine and stopping it turns the light off. This indicates to me the cutout is stuck on. It has the normal low level flashing at idle.

I have exhausted my ideas to fix it.  It does not happen all the time and only at night.  Any thoughts?

Keith

[hsv-001]

Don't laugh, but it could be a short or another problem with the light switch . Remember that it gets power even with the ignition off . Just could be worth checking . Cheers Haydn

[mcl1959]

It sounds more like a regulator problem rather than generator. Maybe both your regulators are faulty.
Do you have stock headlights or sealed beam / H4? If you have H4 you should have a relay to run them otherwise the generator can be overloaded.
Ken

[zulu]

I've had an issue with the light switch in the past where it was making a clicking noise and the generator light was marching in time with it, all standard lights, system etc

[ardiesse]

Gary,

The clicking sound from the light switch would have been the bimetal strip protecting the electrical system from an overload.

Let me think about this for a bit.  The cutout relay in the regulator has a shunt coil and a series coil.  The series coil is wound so that it aids the shunt coil - that is, charging output from the generator will hold the cutout contacts in harder.  A reverse current will oppose the shunt coil and make the contacts separate.

The symptoms that Keith describes happen when you jump start a six-volt Holden from a 12 V car.  The FJ's engine starts, the six-volt generator produces enough output to close the cutout relay, and then there's a good-size reverse current (the 12V battery runs the 6V generator as a motor), the cutout relay says, "shit, reverse current", and opens.  Now there's no reverse current, the cutout contacts close again, and the cycle repeats.

Keith - it's normal for the generator light to come on at the instant you switch the ignition off, but the engine's still turning.

I'm still trying to think through Keith's symptoms.  No joy yet.  Let me see what inspiration lunch provides.

Rob

[ardiesse]

Keith,

The problem doesn't happen during the day, only at night.  So the problem occurs when the generator is supplying a decent load.  If you remove the load, the problem can clear up by itself.  All I can think of is that you have an intermittent short in your armature, particularly when it gets hot.  When you inspected the generator, did you see either thrown solder on the commutator cover band, or any segments on the commutator which looked pitted or burnt?  if you run the engine at night, is there much visible arcing from the brushes?

I had an intermittent short in the armature of a Delco-Remy generator a couple of years back.  Most of the time it was fine.  When the armature was shorted, the generator light would flash quickly just off idle, accompanied by a sound like a burst of machine-gun fire from the regulator.  For ages I thought it was a dirty commutator, because cleaning the comm. with some fine wet-and-dry seemed to make the problem go away.  Then I noticed the brushes were wearing out very quickly, and then the intermittent became permanent.  When I checked that armature on a growler there was at least one shorted coil.

Rob

[KFH]

To answer some comments.  The headlights are original.  I have checked the total current draw of the vehicle at 16 amps with engine off. This is below the 20amp capacity of the generator.  When the engine is running the net current is 0 amps with the maximum electrical load.  My take on this is that the current limit in the regulator is set a little low.  At this stage I have not been able to set it up to confirm this.

I did not dismantle the generator when I checked the brushes as I could access the brushes to check if they were sticking. The commutator was very clean and no arc marks on any of the segments which should probably eliminate a shorted turn in one of the windings. When I overhauled the generator I skimmed the commutator on the lathe and then undercut the mica.  I did not notice any problems with the soldering onto the segments but this problem did not happen for a couple of years.

I have another generator which I have reconditioned so I'll try it to see if the fault still exists.  I have checked all the earthing points out.

Keith

[KFH]

I think I have solved the intermittent problem of the generator light coming on.  When I purchased the car it was fitted with an alternator.  During restoration I refitted a generator.  It was pointed out to me at the Nationals in Toowoomba that the earth wire that runs from the generator body to the regulator was missing   Since fitting this the fault has not reappeared.  The wire was apparently removed when the alternator was fitted.  I had no idea that it originally existed.

Keith

[FireKraka]

Hi Keith it is always good when you find the cause of something.

I run a branch of a company that works on very (very) large diesels and I get really frustrated when I'm fault finding and can't find the cause.

It took a while but good that you got it sorted.

Regards
Neil H 

[ardiesse]

Keith,

Good news, and good sleuthing.  I'd grown up with an EK, which had the generator ground wire as part of the harness; my FC didn't have a ground return wire.  So I added it as part of the rebuild.

I also had an HD X2, in which the headlights flared and faded in time with the indicators, accompanied by wild swings on the ammeter.  Couldn't work it out until I discovered that someone had cut the wire from the battery (-) clamp to the body.  Reinstated the wire, and suddenly the electrical system voltage regulated properly.

Rob