Testing alternator

livn

Registered User
My alternator seems to be acting up and i was wondering what is the best way to test it to make sure its working properly other than taking it to auto parts store. any ideas?
 
In the past I used to disconect the battery cable while the engine was running, and if the motor stalled, it usualy ment the alt wasnt working...but if it kept running, it was ok.

Not sure if this trick works on newer cars, but back in the day it was one way of checking.
 
That just tells you if the battery has a full charge or not.

You need equipment to check the output of the alternator. I'm not sure of the wires but you can use a meter to check the output voltage.
 
Put a voltmeter across the battery posts and see what the voltage is at idle. Should be 14V. 13.5V is acceptable but to me its a sign of a weak alternator. The parts houses will try to tell you that its OK, especially if its one that they sold you to begin with. They don't want to replace it.
 
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