Some ampere numbers for your info / comparison
 

So between my recent alternator travails and some other posts I've read on the board, I though I'd post some numbers of what amperes my 1985 911 Targa had:

1. Shutdown, hood open, hood light on: 700ma
2. Shutdown, hood open, hood light off (son pressed switch): 80ma
3. Ignition switch in "Accessory" position: Hood light on: 1.1 Amps
4. Engine off, ignition switch in "run" position, hood light on, 3.11 amps

Thanks for the #'s
I have been trying to work thought a Alternator problem myself.
When my alternator is cool (engine Cold) I start up the car and alternator runs @ 14 volts but after running the car for several minutes the voltage drops to whatever the Battery voltage is. After running the car for a few hours my battery voltage drops and the car will not start or dies. Luck that the tachometer starts to go tack'o before It get to the point where the car dies's.

Luck that the tachometer starts to go Wack'o before It get to the point where the car dies's.
Sorry!!

Dan,

For me my "health" indicator was my stereo - too high (failed regulator) or too low (failed alternator), but it was not enough lead time - maybe ten minutes. Based on my experience I'd say you have a bad alternator, but Wayne's 101 Projects book has a great troubleshooting guide if you have it.

Brian