Alternator going bad?

[WVZR-1]

Originally Posted by -=Jeff=-

OK, get down to 11 volts when at 5k rpm

Below that rpm it is high 12s, I will data log to a file next time

You do seem to have issues either with the alternator or gauges! The load test is the only check and done on the vehicle. It could be the exciter wire OR maybe even a belt slip. I believe without looking you should be able to apply manual tension at the tensioner while running and see if that improves the charge rate.

LOAD TEST ON CAR - A little math and you'll know. All else is foolishness. You could do numerous replacements and until properly diagnosed still have issues.