[urq] Alternator condition : how to test or evaluate ?

[Huw Powell]

> In my mind, an alternator is a on/off binary device : it works or it
> doesn't.
>
> Now, I have a fresh Bosch voltage regulator in an old alternator, and I'm
> not convince that this unit is working 100 %. When under load, the sound it
> makes it rather shrieking, like if there was something rubbing inside it.
>
> I do have a recent battery, but when I do charge it with a 110V charger,
> it's a lot stronger (from the sound of the starter motor) but after a few
> weeks, it drops to its "normal" level.
>
> So my question is : will a rebuilt alternator keep the battery fully charged
> better than the old semi-rebuilt alternator ? Besides the voltage regulator,
> what are the other bits that can go wrong in an alternator ?
>

> 1983 Quattro with a stock 90A Bosch alternator.

First, have you measured voltages?  Alt output terminal, battery 
terminal when charging and when off, etc.?

What can go wrong on an alternator?

- bearings
- commutator thing (where the brushes make contact)
- diodes
- windings

Now, it is possible that your new VR brushes are "square" on the end, 
and until they wear a bit into a "round" shape to match the commutator, 
current capability may be a bit off, and it might even make noise.

The "shrieking under load" isn't anything like belt squeal, is it?

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/