What Are the Symptoms of a Bad Alternator, ...will the car run off the battery Options

[7TPorsh]

The other morning my car wouldn't crank; lights on dash but no juice. So I charge the battery up and start the car....drive around for a bit. Stop and start after half hour. OK

rive some more and get home...turn the car off and same thing; no juice. I take the battery to FLAPS who analyzes it and says it's bad....even though my meter says 12.5 volts.

I get a new battery and installl. Car starts and runs and I drive back to FLAPS to test system in the car. Master guru technician says machine says I need a new voltage regulator. Of course they don't car it so I drive back home.

i get in the DD and hunt down a new voltage regulator and put it in. Car start and drives...so i drive back to FLAPS. On the short drive there the car is running "on and off".

i make it there. the 2nd master guru technician hooks up the meter and I manage to barely get the car started and running but it shuts off. He tells me the same thing again, the voltage regulator is bad.

I say i changed the voltage regulator and he says no its the one in the alternator. (IMG:style_emoticons/default/blink.gif)

So I coast the car back towards home but couldn;t get it started...going to try again later.
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So does this sound like a bad alternator? Car cranks but wont fire. Always thought it would run off the battery if alt is bad. Please help.

[dangrouche]

here is the comprehensive thread involving the alternator. Also make sure the incandescent idiot light bulb at the instrument gauge is working. If you changed it to an LED, the voltage for an LED bulb does not trigger the charging circuit. Yes, the car does run on the battery, for an hour or less.

http://www.ratwell.com/technical/ChargingSystem.html

[porschetub]

here is the comprehensive thread involving the alternator. Also make sure the incandescent idiot light bulb at the instrument gauge is working. If you changed it to an LED, the voltage for an LED bulb does not trigger the charging circuit. Yes, the car does run on the battery, for an hour or less.

http://www.ratwell.com/technical/ChargingSystem.html

Good call on that reply and (IMG:style_emoticons/default/agree.gif) or the other side is that it runs on the altenator until the revs drop then it dies,I don't know that much(lol) but really feel the OP has a bad altenator and is running on the battery because the brushes in his altenator are screwed or the commutator is carboned up.