Charging system questions
 

What should the voltage read across the battery with the car running? My car:

Engine off: 12.6 volts
Engine at 1500 rpm: 13.8 volts.
Engine at 1500 rpm with AC, lights, stereo, fan, etc. on: 12.8 volts

Normal? Alternator having a hard time keeping up? Time for a new one?

Vic
88 Carrera

That is about where my 83 is.

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Robert Stoll
83 SC
83 944

Vic, your charging system sounds just fine.

Kurt V
72 911E

I think anything in the 11-14 range is ok. Not above 14 though (or below 11 for that matter).
Nick.

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_ _ __ _ _
Nick Shumaker
1982 911SC Coupe
nickshu@yahoo.com
PCA -- Rocky Mtn. Region

VJ,

It sounds within normal range but you might do some more checks. Most any alternator will give you descent power. Putting a load on the system is a good way to test it, but it seems to drop quite a bit. What is the voltage at 2000 or normal cruise speed? Below 13 is a bit low for me and might signal that your brushes are a bit worn...

If it stays above the voltage that the battery shows without the motor running, then normally the alternator is in good shape and able to handle anything you throw at it but I still do not like to see anything lower than 13.

I have installed a digital volt gauge inside the car (lost my alternator last fall) and keep an eye on mine. Normally runs 13.8 to 14.3 with no excessive load, and no lower than 13.6 with everything on, but my alternator is a fresh overhaul unit.

JA

Thanks for the hints, guys ... the car is still under a 90 day bumper to bumper from the non-Porsche dealer (also a Bosch service center, luckily). It goes in next week so I'll have the system checked out just in case.

Vic
88 Carrera

12.8 with the lights on, etc. is a tad low really. 13.8-14.2 is the desired range unloaded, and 13.0 would be the lowest it should go with a normal load. poss. regulator problem. also check your battery clamps for corrosion and the battery ground strap to it's inner fender connection. looseness, or crusty connections will cause a low voltage situation.