Do I need a new alternator?

[gassy]

The car is dead after 24 hrs. Jump it, same thing. Batteries register full charge.
Thanks in advance

[gassy]

what does that involve? learning as I go.

[David]

Put a volt meter across the battery terminals with the engine off it should be about 12.3 to 12.7 with the engine running it should be about 13.7 to 14.5. (those are rough numbers)

[gassy]

thanks man

[gassy]

I was just reading one of the links you posted--the batteries are older than 5 years--i'll start there...thanks again!

[Wil Ferch]

Or...your battery charging light is burned out..and it doesn't just mean your light is gone , it means the excitation voltage is not there and could cause electrical problems.

Do this, turn the key to "on"...but not so far to "start"..is the battery light on ??

Wil

[gassy]

Thanks Wil--my car is in storage at work--otherwise I'd try it right now--I'll try that this week. Thanks,
Christian.

[ThePointman]

I just had my alternator rebuilt and what has been mentioned above is exactly what you need to do. Put a voltmeter across the battery terminals when the engine is running. It Should read from 13.7 to 14.2 volts. If the reading is less then 12 volts you have a charging issue which would most likely be the alternator. Once removed the alternator can easily be tested.

[MAS956]

I'm helping a friend disgnose a charging issue and would like to have the alternator bench tested. The local Kragen said their computer didn't recognize the Porsche alternator and thus they could not test.

Does this need to go to a specialty shop?

Thanks,