Q: Why would my battery drop and my car start running rough only when turning on A/C?

Had A/C Compressor replaced by a shop about a year ago after original quit blowing cold air even when charged. Since then, anytime the A/C is turned on and you hear the compressor kick on, it draws a lot of power and eventually if left on, drains the battery. Even at high RPMS it still drains, just slower. Have gone through 8 alternators now as it fries the voltage regulator. Quit using it through winter as it was not required. Now that summer is here, I cant put it off any longer as it is getting hot. Car has new alternator and connectors, new battery and terminals, cooling fan motor, IAC (idle air control) valve, and vacuum lines. Even bought another A/C clutch as the one that was on with replacement was making a weird noise and was recommended i replace it. Starting to wonder if compressor may be faulty. Have had charging system tested by 3 different shops and they all say it tests perfect. At a complete loss as to what more i could do other than replace the compressor again.

My car has 83648 miles.
My car has an automatic transmission.