Saab: saab 900 alternator problem, digital voltmeter, saab 900

Question
my 1991 saab 900 turbo died slowly in a pouring down rainstorm 5 hours from home. after having it towed and speinding the entire next day working on it, i'm only more confused. it seemed apparent that it was an alternator problem as my headlights slowly dimmed, my windshield wipers were moving slower than a slug and it wouldn't "go" anymore or re-start. so we took off the alternator and was told it was just fine. we had the battery re-charged and it were told it was fine too. we replaced some frazzled wires and the belts, since we had it apart. after putting it all back together, we hit the road, only to have it die on the highway with the same initial problems.

so, how would you diagnose this? and is the voltage regulator built into the alternator for this car? any help is appreciated!!!

Answer
Cali:

  Since the evidence of a bad alternator is so strong, my guess is that the diagnosis of its being OK was wrong. You can check this yourself quite easily as follows; (The regulator is built within the alternator itself).

 A. Get a digital voltmeter...with the car running at idle, the battery voltage should be 12.5 volts or greater; if you rev it up, the voltage should be 13.5 volts or greater. If not, then the alternator is bad. Also, at night with the car idling and headlights ON, rev up the engine and note if the lights brighten slightly. If so, the alternator is ok.

 B. Go to <www.harborfreight.com> and procure the following   Alternator/Battery Tester U.S. General p/n 46972-3VGA, $3.99. You simply connect this to the battery for immediate results. It is accurate and the price is right!

  Hope this helps,
                  Jerry