Now I just recently swapped my stock alt with an new H.O. and my voltage is dropping under normal conditions, such as ac running, lights on etc. I haven't changed anything such as wiring. Just direct swapped. Those are the only loads on the alt since I don't currently have my sub amp installed.

I know voltage drop is suppose to happen, but not like its doing now. Cold start is around 14 - 13.9. But when load is applied i'm dropping to like 13.2 -13.3. Sometimes lower but i rev before it gets any lower.

What could be some of my issues?

what vehicle are u refering to.

2001 Ford Explorer

it sounds like u have the same problem that i do. there is a voltage regulator in the alternator or ur voltage is controlled by ur ECU. when it heats up the voltage will go down. dont know if u can put an external voltage regulator on it. if u can i know u can get the blue fin regulator for fairly cheap.

Im thinking its controlled by the ECU, not unless mechman puts voltage regulators in his alternators. But if I was to go with a blue fin regulator, the amps of would have to be equal or greater than the amps of my alternator?

Upgrade the power wire from the alternator to the battery and add a ground from the grounding stud on the alternator to the battery. Also try putting the batteries on a slow charge overnight with a battery charger.

All wire has been upgraded with zero gauge and batteries have been charged but not slow charged