Is my alternator failing?

[Sam]

This isn’t on a Porsche.

It’s on the stupid sort of car that looks like it’ll need the whole engine, gearbox and subframe dropping to remove the alternator.

Battery is new, reads ~12.x with the engine off.

At idle reads ~14.x.

When revved reads ~12-13.x

When lights are on drops to ~12.x at idle.

It’s clearly charging a bit, but after a 2 hour drive the charge light started flickering on and off and 15 mins later it died.

[SeanP]

Sounds like the regulator is failing to me.

[misteralz]

What Sean says. I'd chance a new regulator pack first. For the sake of 25 quid or so and less disassembly it's worth a shot.

[Lightweight_911]

.

If it's the car I think it is (Testarossa), the VR is integral with the alternator &, as Sam says is not particularly simple to remove - mid engine layout - (although I'm fairly sure it doesn't involve engine removal).

An obvious question but have you checked the belt tension (bearing in mind the awkward adjustment access) ?

.

[Sam]

Thanks guys.

Yes, the regulator is part of the alternator but looking again I reckon I can remove a grill and panel and get it out without dropping everything. Hopefully.

I did check the belt!

[MikeB]

Check that your main battery lead to the starter motor is tight, I had a similar issue and that’s what it was. The starter was working fine so I didn’t think that was the issue