Alternator/generator/regulator problems of the 2010 Ford Mustang

My car battery is being drained and going dead, while car is completely off after sitting for more than 10 minutes. I have had the battery checked, alternator checked, and all fuses pulled and diagnosed to see if there was a shortage or bad fuses. All wires, connectors, and fuses were documented to be in good standing. The car had been driving perfectly and cranking with no problem, then this problem occurred out of the blue. The same day it went dead, that morning is when my car started up slightly different; but I did not pay it much attention, since it did crank. Later that day, I started my car and it slightly took a second longer to crank; which is when I then figured something was going wrong. I made it to my destination - where I was there for about a 1. 5 hours - got in the car to leave, and thats when I first experienced a completely dead battery. I then was able to get a jump, which started my car right back up; whereas, I then headed to autozone and good year tires to have my battery tested. Each place stated that my battery was 100% and charging perfectly. I then went to an auto electric shop after googling the problem, and seeing that many others have experienced the same problem with the same year and previous Mustang models. After 5 hours of diagnosing my car and seeking what the problem may be, I was informed by the car technician that the issue of the draining is being caused from the malfunctioning of the Smart junction box - located in the foot panel of the passenger side.