How can I test my alternator?

[Althejazzman]

Hi all,

I believe that my 924 has a duff alternator. I drove it for the first time last weekend, and by the end of a 15 minute journey the battery light was flickering and the gauge showed only about 11v. I am using a second hand battery, but it took a good charge a while back and still reads 12.2v.

The alternator on the 924 must be the only part that is harder to access than the 944! It's stuffed in amongst the exhaust downpipes, steering rack and a water hose. Only once I had released it from it's fittings could I test it with a multimeter.

With the engine off, I only managed 11.97v at the alternator hot terminal, so I'm losing about 0.23v between the battery and the alternator. I also measured resistance between the battery +ve and the alternator hot terminal and that read 200 Ohms.

Perhaps somebody could tell me if this means anything, and where I could get it refurbished.

[rapidstu]

i believe if you just measure the battery with the engine off you will get 12 ish volts but if you start the car this should go up to 13 or 14 volts. But i'm not an electrician.
If its duff you should be able to get it rebuilt for as little as £40 but exchange units can be more expensive.