My 2006 F150 battery light is coming on at different times. Usually when it is very cold and dark. If I rev the engine above 2000 revs it will go out but only temporary. I have replaced the fan belt and the tensioner feels very strong. Also, I checked the alternator and battery connections they seem fine. The battery is less than 2 years old. Any help would be appreciated. Thanks
Doug from New Brunswick Canada
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Welcome to the forum, Doug!
From what you describe it sounds more like the alternator or voltage regulator (located in the alternator) is on its way out. Most parts stores can test that for you or you can do the same thing with a volt/ohm meter. Under normal conditions your alternator should be putting out 13.4 to 14.5 VDC or so at an idle.
This condition can also be caused by a bad cell in the battery and the same test (engine off) can prove that out fairly quick as well. As indicated, your battery should read between 11.5 and 12.6 VDC since each cell typically provides about 2.1 VDC.
Hope that helps!
Mac
From what you describe it sounds more like the alternator or voltage regulator (located in the alternator) is on its way out. Most parts stores can test that for you or you can do the same thing with a volt/ohm meter. Under normal conditions your alternator should be putting out 13.4 to 14.5 VDC or so at an idle.
This condition can also be caused by a bad cell in the battery and the same test (engine off) can prove that out fairly quick as well. As indicated, your battery should read between 11.5 and 12.6 VDC since each cell typically provides about 2.1 VDC.
Hope that helps!
Mac
Hi Mac
Yesterday I measured the battery volts with the engine at iddle without any lights on and read 14.4. Turned the lights, wipers heater fan on and the volts dropped to 14.0. With the engine off the battery measured 12.3 volts. Today the battery measures 12.3 with the engine off but when I start the engine the voltage drops to 11.8 and the battery light comes on. So, I'm assuming the alternator needs changing. Thanks
Yesterday I measured the battery volts with the engine at iddle without any lights on and read 14.4. Turned the lights, wipers heater fan on and the volts dropped to 14.0. With the engine off the battery measured 12.3 volts. Today the battery measures 12.3 with the engine off but when I start the engine the voltage drops to 11.8 and the battery light comes on. So, I'm assuming the alternator needs changing. Thanks
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