Can someone please check their voltmeter?

[piggiepigg]

hi folks,
i understand that volt meters in cars aren't exactly acurate but bear with me a sec. i noticed when revving the motor that the cabin lights dim and the volt meter goes from ~14v to ~12v. another member here explained that this may be completely normal. and by turning on the headlights and retrying this, the voltage should remain steady at 14v's and the headlights should not dim. thank you member that was exactly correct. however in drive and while driving down the road, it is dipping to 12v indicated or lower, sporadically. can someone please try this test on their own vehicle to see if you get similar results?

i'm troubleshooting the alternator and want to know it's bad before yanking it. i had it tested at checker, well they tested the voltage at the battery with the headlights on and the blowermotor full tilt while the car was running and bingo solid 14 volts. but it has not been tested in drive.

thank you for your help


how do i post pictures? i read the faq and there supposed to be a browse option at the bottom but i don't see it. i only see 'insert image' icon and when i hit that it says 'enter the text to be formatted'

[Canucklehead]

Originally Posted by piggiepigg

however in drive and while driving down the road, it is dipping to 12v indicated or lower, sporadically. can someone please try this test on their own vehicle to see if you get similar results?

It doesn't matter whether you are in drive, neutral, going backwards or just sitting in your driveway. If you put load on the engine with the headlights off the alternator will stop charging the battery until conditions stabilize. This is done to improve fuel economy. If your voltmeter is dropping below 14VDC and you aren't accelerating you likely have a VR problem (bad diode).