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Low voltage

(1999 Chevrolet S10)
in Athol, MA on June 01, 2010
Would an alternator just die with out first showing signs of failure such as dimming lights,slow wipers and start up problems?
I was driving out of town 25 miles when battery light came on and voltage showed appx 11 amps. I was able to make serveral stops and starts over 4 hours and also make it back home. Traveling at least 75 miles for the day. The next morning my truck started right up and was maintaining appx 11 volts. If it were the alternator wouldn't my battery be dead?
Cables and terminals seem to be fine as well as the battery.
Could it be another problem vs. the alternator?
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Popular Answer
A fully charged battery will read 12.6 volts at rest, a short or open circuit in an alternator can happen at any time without warning. A quick check of the charging system is turn on the ignition switch to the on but not run position do you see an icon on the instrument panel representing a battery, if you do not see this battery icon the alternator is not seeing power to allow it to charge. Start the engine does the battery icon go out. A more complex but good diagnostic test is checking "voltage drop" on the battery ground and power cables. You can find a video on how to do a voltage drop test on youtube. Put a volt meter across the battery terminals with the engine off, at rest the battery voltage should be 12.6 volts if the battery is fully charged. Now get a friend to start the car while you watch the voltmeter, the voltage reading across the battery should read approximately 14.6 volts if the alternator is charging correctly.
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