Instructions

You can view power usage of today, yesterday and 2 days ago. You can also view
apps' foreground and background activity time, and their power consumption.
Power Saver Options
Go to "Settings" > "Battery" > "Power Saver Options" > "Sleeping Mode".
This feature can sense when you might be sleeping, and then switch to Low Power
Mode to make your phone more power-efficient.
High Performance Mode
Go to "Settings" > "Battery" > "High Performance Mode".
The system will operate in high performance mode, but it will increase extra power
consumption.