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Windows' Battery Saver Mode lowers the system resources to increase battery life. Hibernate mode saves a snapshot of your current Windows session to the hard drive so you can turn the laptop off. The higher your screen brightness is, the faster you'll drain your laptop's battery. Windows 10 logs the CPU usage of all the programs you have installed to see if there's any software that's hogging the laptop's browser. Turn off Bluetooth and Wi-Fi to save more power.