Easy Alternator test? Options

[ChrisReale]

Is there an easy multi-meter test you can do to see if the alternator has crapped out? I guess the fact that my battery doesn't charge is proof enough, but I just wanna make sure.

[type47]

I'd like to listen to a discussion on how the VR works. Here is a link to the PP elec diagram containing VR and Battery:

http://www.pelicanparts.com/914/parts/Elec...lectric_74E.jpg

[Dave_Darling]

I'd like to listen to a discussion on how the VR works.

It compares the battery voltage to the alternator voltage. When the alt voltage is higher than the battery voltage, it disconnects the field windings of the alternator, making it no longer charge. When the alt voltage is lower than the battery voltage, it connects the field windings of the alt, making it charge. It effectively turns the alternator on and off, over and over again, pretty quickly.

That is a simplified version, at least. There are more details, and I think those start taking into account how quickly the electric fields in the windings build up and decay, and how the compared voltages are actually biased so you charge at ~14V rather than ~12V, but the description is a half-decent overview.

I believe the alt light runs off of the alternator voltage wire that goes to the VR. I'm not sure exactly when the power for the light has to go through the VR, but it probably has something to do with the way the light is used to "bootstrap" the alternator to get it to start charging.

--DD