Ongoing Arrow alternator/charging problem

Hi everyone,

This group seems especially knowledgable, I hope you don't mind a
question about a friend's plane.

Its a 78 Arrow and is being used by a FBO for training. For the last
month or so, they can't seem to keep the battery charged. Started a
month ago and the alternator was found not putting out anything.

Swapped it for a rebuilt alternator and two weeks later -- dead
battery again. Same thing -- no output.

Took the alternator back to the seller who tested it and confirmed
that it wan't putting out. Bought a brand new one and installed it.
Seemed to be putting out, but pretty low amperage except at high RPMs
(Arrow has a load meter, not charge/discharge meter) .

Exactly two flight hours later -- dead battery. Apparently, the
alternator isn't putting out again. And the A&P is at a loss. I
suspected the voltage regulator, but he says he's had it tested.

Has anyone else run into a problem like this before? Or can anyone
offer a suggestion on where to look for the root of this problem? I'd
like to help him get this fixed -- we're both working on Instrument
time and we're splitting the time between his Arrow and my Cherokee.

Thanks guys...



Chuck