jsoderbe

Hi guys,

I have a strange problem with my 2001 996 Convertible. When I start it cold the volt gauge reads around 13.5 V, which I guess is pretty normal. However, when I turn on the litronic lights I loose 0.5 V, and when the engine is at working temp I loose almost another volt, meaning the gauge barely reads 12.5V.

This is really strange, and I am afraid to be left stranded some day.

Does anyone know what might be wrong? I would guess it is alternator related, but if anyone could be more specific I would be very grateful.


Regards,

Johan

fpb111

Most healthy charging systems will start initial charge at ~14.2 volts and only drop off to ~13volts after extended recharge run time.

How old is the battery? If it is more then 3 years it might be time for a new one.

From the symptoms you describe it does sound more like an alternator related problem. You could pull the alternator and take it to an auto electric shop for testing and/or replace it with a rebuilt unit.
You could replace the regulator, mounted on the back of the alternator, with a new one. The brushes that wear out and cause many of these type problems are part of the regulator.

The Bosch alternators are used on other makes and parts are available through many channels.
The one on my 2004 Mercedes ML is the same as the 996.
These are some regulators that fit the one in our cars.

Macster

I'm with Frank that the alternator is at least suspect.

But before I went to the trouble of removing the alternator I'd have the charging system and battery checked out first with the alternator left where it is.

jsoderbe

Hi, thanks for the replies! Just to add some more info; the battery was my first suspect, so that one is new since 2 weeks. It seems to be holding up so far.

Regards,

Johan