electrical problem.....help please.
 

im having an overcharge problem with the mustang...i replaced the alternator thought that was the problem. i changed it then 2 weeks later the alt gose bad again..so this time i take the alt go to autozone have them test out the alternator it passes no problems so i was like okay give me a brand new batt. he was like sure no problem...i bought a brand new batt. put the alt back on. new batt on started the mustang the gauges read fine for about 30sec. then it started to over load again. as soon as i seen that i shut down the car and just left it parked...i come back tonight just to crank it over and the car is DEAD....WTF?? no juice what so ever. nothing couldnt unlock the doors or anything i took the battery off. i do not know what is going on here...where is the car taking power from? i took the system wire off the car thinking that might be the problem NOPE....maybe its a bad ground? where are all my grounds located?? anyone know? if anyone knows anything please help me out thanks.