I hope somebody can give me some suggestions. Its about my g/f's car. The other day she started her car and the battery light came on. The battery seems to be fine and is not running dead. Then periodicaly the light will go off then come back on shortly after. Its almost as tho it goes on and off when going over bumps in the road, but this is not always the case.

Any suggestions would be great.

 

Take a look at the alternator and make sure the wires are tight, and that the belt is ok.

 

i checked the belt and its fine. But I still have to check the alternator. Also is there any way to test the alternator without taking it into a shop?

 

here is a cheap way to see if your alternator is working. Turn you car on let it idle. Then unplug the negative cable from the battery. If the car stays running the alternator is good.

DEF

 

another way to test alternator.. with car off. put a voltmeter on the battery of the car.. u should get somewhere around 12V, then, while keeping the voltmeter on, start the car... if the alternator is good, the voltage should jump up to around 14.4V.
and you said the belt is tight? and the alternator is tight too? you cant move it back and forth to change the tension on the belt?

 

probably the alternator...specifically the contacts. usually worn out around 120k-150k miles. the reason that the light comes on then goes out over and over is due to the contacts(brushes) no longer have sufficent tension to conduct power through the windings inside the alternator. replacing the alternator will take care of this.

 

so if the alternator is worn out seekerONE then if i put a voltmeter on the battery would that tell me for sure? I just hate to have my g/f spend $100 or whatever it costs for a new alternator if thats not the problem

 

just an update to everyone. I replaced the alternator last night, and it appears that all the problems are solved. Thanks to everyone who took the time to give their advice on this topic.