Confirmation of alternator problem

Symptoms sound like it's only a diode in the regulator that's gone.

AJH

I don't think that would cause crackling on the radio. Check all the connections in the alternator/battery circuitry for soundness.

and if it is the diode, you will find that when stopped, the current flow will reverse turning the alternator windings into a giant electro-magnet which will use up the battery current overnight and leave you with a stone dead flat battery by morning

Might just be the brushes.

Good point, I wouldn't know about crackling on a radio ;-)

AJH

My understanding is one diode fails open circuit, this means the alternator only charges through one leg of the rectifier and hence its voltage does not exceed battery voltage during a half cycle, current flows via the ignition bulb through that half cycle, so it weakly glows. For a short to occur two diodes need to fail.

AJH

They are much more likely to make the characteristic whine rather than crackling and flickering lights.

In the other case when the ignition is off and the diode still glows dimly is when you get the flat battery. The easy fix is drop it in to a specialist to get it overhauled and a lot cheaper than a new un. Derek

"12.8 with engine off and slightly down when engine is running (12.45 and fluctuating)."

Less with the engine running, I'd say its a lot more than on its way out. I priced one up for my 2.5 naD at £45 as my charge light comes on now and again, last time I just smacked it with a spanner and it started working again :)

-- Jon

Fisrt of all do what Dave L has suggested - check all connections for security and cleanliness. I'd start at the rear of the alternator.

That sounds like worn brushes.

Thanks for all the advice. I think my best bet is to get a replacement and then overhaul the old one cos I need to use the old gel every day.