Battery not holding charge

2000 SAAB 9-5
31,000 MILES • 6 CYL • 2WD • AUTOMATIC
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WYLIE
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The battery went dead. When I start the car with a jump, and the car is running, and I disconnect the positive pull on the battery, the car dies. I think it is the alternator, what do you think?
Mar 22, 2011 at 11:27 PM
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CARADIODOC
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I HOPE it's the generator because if it was working, disconnecting the battery cable can destroy the many computers on the car from excessive voltage. That was a trick done many years ago by mechanics who didn't understand these systems. A better and safer test is to use an inexpensive digital voltmeter to measure battery voltage. With the engine not running, a fully charged battery will read near 12.6 volts. If it is closer to 11.0 volts, suspect it has a shorted cell. With the engine running, the voltage must be between 13.75 and 14.75 volts. If it stays near 12.0 to 12.6 volts, suspect the generator or voltage regulator.
Mar 22, 2011 at 11:42 PM