Had some suspicion that my alternator was getting tired as after starting the light stayed on a tad until the engine was revved.
Took some readings and was a bit low ticking over but seemed ok when running at higher revs...but
Today thought starting was a bit more laboured but when started no light on even at lowtick over, so got the meter out and found 14V on slow tick over raising steadily to just under 19v with some revs!
So thats the regulator gone then!
Had them fail with zero output but not seen high output before, luckily battery is fine.
FYI can get new reg, brush kit and even rectifier kit for total of about £12 + VAT so will rebuild and see...
Also ordered new alternator as only £43 so having rebuilt spare could be good..

I've had one go high on an old Vectra many years ago, went to about 15.5v

Kwakerman said:

I've had one go high on an old Vectra many years ago, went to about 15.5v

Click to expand...

Seems like it does happen, just weird as normally just die, however stripped it out so easily rebuilt.
In normal electronic circuits have seen this happen if regulators lose their 0V / earth connection, so wondering if corrosion / oxidisation on the reg terminals have made it go tad off course.
Checked the brushes while apart and loads of contact left.
As will be a few days before parts arrive I may just clean it all up and try it.