Paul,
Do you mean the internal regulator inside Alt. ??
P.S. I just start the car from chargring Jumper, then i went to supermarket , diconnect the Bat + Termnel , then came after hour, then i start the car , and the needle stay at 14.5 V. its was strange, even with 900 RPM !!
Then drive the car for 10 min. every thing was fine, then again after i top the car and Engine goes to 900 RPM, the needle start to play up and down, 1/4 - 1/2 position !
BTW, i change my Alterenator before year ago with NEW one!