Alternator output question
 

My alternator/charging light (1983 911) is on steady with a occasional flicker. Is a constant reading of 11.6 at the battery terminal at 1200 to 1800 RPM enough to cause this? Thanks.

Sounds like a bad alternator. should be about 13-14 volts

Regulator appears to be shot, maybe the alternator. at that RPMs it should read 14.1-14.3 volts. 11.6 your battery is dead or damaged.

Remove the alt, then the regulator and inspect it, if good, put back carefully and have it bench tested, bring your pulley halves with you so they can put a belt on it.

Have battery tested too

Your alternator is probably shot. A VR regulates the voltage leaving the alternator. In other words, it limits what the voltage that goes to the battery. At idle or at 3000 rpms, it shouldn't be more that 14.3,.5 volts. I agree with the recommendation of pulling the alt. and look at the VR, particularly the brushes. If they are severely worn, perhaps not all the volts are getting to the battery.

What does your battery read with the engine off?

do one of 2 things, one of which will end with the second.
take the car to some place like advance and they will check it for free.
2, you obviously have something bad. take the alt out and take it to a shop and have it rebuilt/repaired.

Check your battery first. One bad cell will wreak havoc on your system.

Check your 14 pin engine connector. A bad connection there will prevent charging.

Pin #11 to be precise as to which one will get you! :)

Thanks to all you guys that have responded. My battery is at 12. It has no trouble keeping a charge as the car has set for a month or so but started up up right away. I'll check the 14 pin engine connector as soon as I figure out where it is.

14 pin connector for the engine harness is under the plastic cover in the rear engine compartment. Down low on the side of the panel near the 3 fuses. It just wiggles out.

Quickest check that I know of: with engine turned off...check battery voltage (should be at least 12.2V)...then..start engine...check battery voltage again (at battery)...should be more then 12.2V....if not...you have a problem.
Then...altenators use a feedback system to excite the stator coils...if you feed 12v (battery voltage) to this terminal at the altenator...it will output full voltage...only do this for a very short time.
If the alt puts out big volts (could be as much as 16V) then the alt is good and the reg is bad.
Bob

I had the same issue, my battery was good, but when running I would only get a reading of around 11V across the battery terminals. In my case it turned out to be both the brushes in the voltage regulator and the slip rings in the alternator. Here is a link to my earlier post with some photos and how I "fixed" it. Not sure if an 83 has the same alternator as my 86 but it is probably similar.

http://forums.pelicanparts.com/porsche-911-technical-forum/765796-temporary-alternator-fix-cheating.html

Check your Voltage regulator, it acts really funny when it's on the way out. How many miles on your car. If it's under 100K I would bet it is a regulator and not the alt itself. Brushes on the VR should be about 3/4 of an inch long when you remove it. Mine were about 1/2 inch and would not make good enough contact to generate power. I had few, to no voltage spikes, just low voltage at the battery with the car running. Sound familiar. I have a spare regulator if you want to try it first. I'll make you a deal on it. PM meSmileWavy