Anyone have any ideas as to why the car would not be producing enough voltage? I had the alternator re-built about 4 months ago and the voltage output has gotten steadily worse. I had the alternator checked today and it is putting out about 14.1 amps off the car so it's fine. When the lights, fan, and a/c are on it's only indicating a little over 12 volts on a meter. Is there anything that could be causing a drain on the system?

I keep frying batteries. Unfortunately this caused me some starting problems while at Devek days.

Eric Van Tassel

Black/Black 86.5 5spd

=====================

Eric,

I get the same type of voltage drop, that is reads around 12v., when the a/c and lights are on and haven't experienced any problems. If you're losing batteries, I suspect the problem is elsewhere. I assume you've already done the obvious stuff like cleaning all your ground connections and made sure the connections to the alternator and battery are tight and clean. Cleaning these connections corrected a low voltage condition on my car.

Is it possible you've got a drain on the system, when the car is off, that is pulling the battery down? I'm not sure what the off current drain from the battery should be.. probably just the clock. I'd check the "hidden" lights (glove box, engine compartment) and perhaps measure the current from the battery with the car off with a multimeter ... just put in on 'amps' and hook it in series w the battery. Maybe someone else knows the off state

current drain.

This is all I can think off that might be killing your battery if the alternator is putting out 14v..I assume you meant you could read that on the car with the engine running. If you don't get that w the engine running and lights/ac off then you could still have a problem w the circuitry that activates the alternator. There 's a fairly simple way to test it on the car. Check Greg Nichols tips section. If you can't find it, email me and I'll send you the procedure. Basically, the alternator is activated by current flow thru the "low voltage warning" lamp on the voltmeter and a parallel 68 (?) resistor. If you're not getting enough current thru there to the excitor coil of the alternator, then it won't operate properly but could test ok OFF the car. Does the warning light come on? Even if it doesn't, it could still be defective. You'll be able to check this w the procedure.

HTH,

Jim

==================

At 09:14 PM 8/10/01, Eric Van Tassel wrote:

>Anyone have any ideas as to why the car would not be producing enough voltage? I had the alternator re-built about 4 months ago and the voltage output has gotten steadily worse. I had the alternator checked today and it is putting out about 14.1 amps off the car so it's fine. When the lights, fan, and a/c are on it's only indicating a little over 12 volts on a meter. Is there anything that could be causing a drain on the system?

>I keep frying batteries. Unfortunately this caused me some starting problems while at Devek days.

1) Don't depend upon the voltmeter in the dash. use a good voltmeter at the jump start terminal or the battery to check output voltage.

2) I assume that you meant 14.1 volts, as 14 amps would not be sufficient to run the car. If so, this is fine.

3) The ribbed belt needs to be really, really tight. If you use the Porsche belt tension gauge, the timing belt should be at 5.0 on your car - the alternator should be at 9!

4) The most common problem is probably resistance build-up in electrical connections all over the car, with the flexible printed circuit board in the pod being the biggest offender for indicated voltage. Some other points to check: the ground strap on the bottom of the engine; the medium-heavy wires from the alternator to the starter; all battery cables and connections; and the ganglion behind the jump start terminal. if you are missing the plastic cover over the wire at the jump start terminal, water can get in and cause severe problems due to corrosion in the wires.

5) There are LOTS of things that can cause battery drain.

Wally Plumley

928 Specialists

====================

> Anyone have any ideas as to why the car would not be producing enough voltage? I had the alternator re-built about 4 months ago and the voltage output has gotten steadily worse. I had the alternator checked today and it is putting out about 14.1 amps off the car so it's fine. When the lights, fan, and a/c are on it's only indicating a little over 12 volts on a meter. Is there anything that could be causing a drain on the system?

> I keep frying batteries. Unfortunately this caused me some starting problems while at Devek days.

>

> Eric Van Tassel

> Black/Black 86.5 5spd

--------

Hello Eric,

It was nice to meet you at Devek Days. You didn't get this fixed when you were there? You stated measuring 12 V, but not where and at what RPM.

- the best place to measure the voltage is with a real volt meter (don't rely on the dash gauge) at the alternator, but that isn't really

practical. So, I'd suggest to measure voltage at the jump connector on the right side of the car under the hood.

- if you're seeing 12 V at low RPMs with all that load turned on, I'd say your alternator is OK. The maximum voltage the alternator can produce is about 13.5 V, but that will decrease as the electrical load increases. As I'm sure you've read in previous posts, make sure all the ground connectors are clean at their connection to the body and engine. Check the cables, that is a long run from the alternator back to the battery. Are the battery cable contacts clean [this isn't a normal problem with 928 batteries that sit far away from the heat of the engine]? You said the amps were checked, did they check the diodes? Just because it was rebuild doesn't mean the diodes were replaced. Was your battery checked? A bad battery can cause all kinds of crazy symptoms.

Hope this helps,

Rich

=======

The alternator should put out 13.5v, or a bit better, so that's what I'd check. The gauge light is in the excitation circuit and if it's on it would indicate a bad alternator anyways.

I'd pull the alternator and have it checked at an auto parts store. They'll be a bit perplexed on how to connect it but it'll work.

I put in the regulator and brush assembly for my Bosch unit from http://www.drivewire.com/ . Much cheaper than a rebuilt unit. I've got a Audi alt in but I recall seeing the parts for the real 928 alternators.

Glen