There has already been written many posts about this problem, but only accepted solution is to call Dell service. I would like to add that it is not a real solution. My PC is not recognizing charger after it hybernates automatically when unplugged in sleep mode. Mainboard has been replaced several times, Windows has been cleanly reinstalled, BIOS went through couple of version updates but problem still persists. Motherboard replacement today end up in error after some minor change of BIOS setting, PC was not able to load Windows nor allowed to open BIOS setting after that and technician had to install old board back. Solution of DELL support? "We will send technician again with another board".
Frankly, I expected better product and better service when I bough this high end and high priced notebook.