Battery and/or alternator problem - Automotive Wiring and Electrical


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Battery and/or alternator problem

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Auto Repair Home>> Automotive Repair>> Automotive Wiring and Electrical

rsaltsman
New User

Oct 3, 2009, 3:18 PM

Post #1 of 2 (956 views)

Battery and/or alternator problem	Sign In

I just bought a 1997 pontiac bonniville 3.8L v-6 it has 193,000 miles. Driving home 3 days ago the cars gauges and lights start acting eratically. Then the car shuts down. After I cleaned and tightened the posts and got a jump I drove home. The cars battery gauge kept jumping from about 10 volts to 18 volts. As soon as I got in the driveway it died again. I had to give it another jump to start it. The battery gauge still jumps from high to low volts but hasn't died again yet. I tested the alternator by touching the back spindle with a screwdriver to see if it is magnetic. It was. The battery is only 8 months old. We've had the car for 3 weeks and the battery gauge just started doing this 3 days ago.

Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 3, 2009, 3:24 PM

Post #2 of 2 (953 views)

Re: Battery and/or alternator problem	Sign In

Quote

I tested the alternator by touching the back spindle with a screwdriver to see if it is magnetic.

I don't know where you got that idea from but it certainly won't tell you if your alternator is good or not.

The first thing you need to do is fully charge the battery before testing anything. The use a digital voltmeter to measure the voltage across the battery with the engine idling and no accessories on. You should see approx 2 volts higher than the "engine off" battery voltage.

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