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Alternators
Car Batteries
Ford F-150

What would cause a battery to drain and not charge with the headlights on but charge up fine with the lights off?


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2006-07-29 04:40:11
2006-07-29 04:40:11

Sounds Like Your Voltage Regulator Is Bad. This Is Inside The Alternator On Most Cars. You May Have To Remove It For A Test. But Lots Of Parts Houses Can Test Unit On The Car. Also Your Battery May Be Weak. Start With The Alternator First. Good Luck The alternator could be marginal. If one or more of the diodes are faulty the alternator will not be capable of producing enough current. You should be able to have the alternator tested at a local auto parts retailer such as checker, Kragen or Auto Zone. If a diode is faulty those tests can certainly detect it.


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