Alternator quits charging after ~2400 RPM

[JRPony]

Heres the scoop:
As I was merging on to the freeway, I mashed the throttle. The car accelerated for about a half a second, then the engine hesitated for about a second, then started accelerating again. After that, the battery light was on and the voltmeter was dropping.

So I thought that I had snapped the drive belt. But power steering and a/c worked still. I still decided to pull over and check it out real quick. But when I came to a stop, the battery light shut and the voltmeter went up. After doing some experimenting, I found that below 2400 rpm, the alternator would charge but anything above that and the battery light would come on.

So its pretty much a stock 88 5.0. I put on a PA perf 130 amp alternator about 2.5 years ago. The belt is ok and tight. Battery connections are ok. My first guess is that the regulator went out. Anybody else agree or disagree? Thanks in advance.

 

[88mouse]

take it down to the local auto part store and have them check it just to make sure.

 

[JRPony]

I load tested the alternator myself at about 2000 rpm and its putting out 110 amps. Above 2400, it drops to 0. Does anyone have an opinion on this?

 

[rockytoohot]

Could be a short in the windings. I had the same problem with an alternator once but it would spike badly and cook the regulator but only at higher rpm. The test bench at my local rebuilder couldn't find the problem as there test bench couldn't spin the alt fast enough. I would recommend replacing the whole unit and save the hassle.