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Do cars run from alternator once started ?

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Old Jul 21, 2004 | 03:30 PM
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Default Do cars run from alternator once started ?

Hi guys - quick (and hopefully easy) question.

I just bought a Hawker battery and was wondering -

The battery is only used to start the car, the alternator provides current/amperage to the circuit once the car is running/alt is spinning, correct ?

The battery would only be drawn on if the amperage the alternator is putting out is exceeded (and I think the factory alternator is 108 amps, right ?).

Just need to be educated with an official answer please.

Bad30th
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Old Jul 21, 2004 | 04:48 PM
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The battery also provides a function similar to a capacitor, in that it "smoothes" voltage fluctuations. But basically, yes... if you are drawing more current than the alternator can supply then you will end up with a dead battery or a dead battery.
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Old Jul 21, 2004 | 05:07 PM
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Originally Posted by PFDarkside
The battery also provides a function similar to a capacitor, in that it "smoothes" voltage fluctuations. But basically, yes... if you are drawing more current than the alternator can supply then you will end up with a dead battery or a dead battery.
That's somewhat true. The battery basically starts the car and runs accs' when the car is not started. As far as the "capacitor" comment, a 12v battery cannot discharge quickly enough to provide this function unless it is designed to do so. Most are not. It may provide a "cushion" for the charging system, but unless you have a Mega-Watt stereo system with multiple big *** amps that should never come into play. If your Alt. is functioning properly this should never be an issue. You could test the "running off of the Alt." theory by unhooking your + cable while running and watch it continue to run, just not on newer cars. Computer controlled cars could see a MAJOR voltage spike in this scenario which could possibly kill the ECM.
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Old Jul 22, 2004 | 09:17 AM
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Thank you for the replies, that's exactly what I needed to know.

Bad30th
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