battery light came on checked charging system , was at 12.4 low , alternator in/op , checked again in morning with my fluke 14.7 engine cold ran unit fully loaded, lights a/c ect, noted voltage gradually dropped to 12.3, inspected alternator belt ect ect, noted 4 pin plug going into alternator, does alternator have internal regulator or is there an external regulator ?

 

dgallegos, the voltage regulator is external (part of the ECU). What you are describing is most likely bad battery cables. If you start up the car with the engine cold and then turn on a lot of electrical stuff, let the car sit for like 5 minutes with all the stuff going and then cup your hand OVER!!!!! (DO NOT TOUCH!!!!!) the battery posts. I bet you will find one of them extremely hot and the other at engine bay temp. The hot one is your bad cable. Replace and see what you have at that point.