Solução
Citando o site de suporte oficial da Samsung:
Battery Life Extender sets the maximum battery charge level to 80% in order to extend the life of your battery.
In order to turn Battery Life Extender off in Windows 7, you will need to access the BIOS. To access the BIOS and turn this function off, follow the steps below:
Turn your computer on.
When you see the Samsung logo appear, press the F2 key repeatedly. The BIOS appears.
Note: If the BIOS does not appear, turn your computer off and follow the steps above again.
Use the right arrow key on your keyboard to move to the Advanced tab in the BIOS.
Use the down arrow key to highlight Battery Life Cycle Extension, then press Enter.
Use the up/down arrow keys to select Disabled and then press Enter.
Press the F10 key to save and exit. Your computer will now start up and Battery Life Extender is disabled.