Alternator questions

[MrShanks2U]

A few days ago I noticed that my battery light would come on and my voltmeter would die whenever I got above 3500 RPMs. Last time this happened, it was my alternator. I took the alternator off and had it tested at Advance Auto. They said it was charging fine.

One thing I noticed is that the tester at Advance didn't really seem to test the alternator under higher RPMs. If this is the case, wouldn't that mean that they aren't fully testing the alternator's ability to charge? Maybe I'm reading in to my observations too much. Where should I go from here?

 

[Big Jim M]

Their machine puts a load on an alternator. Most times if they say it is good, they are correct.
Could be a loose wire or perhaps a ground that is going away. I'd check the body grounds, and see if the thing does it again.
Big JIm