Galaxy Note 9: How can I optimise and extend the battery life

On the Settings screen, tap Device maintenance > OPTIMISE NOW.

The quick optimization feature improves device performance through the following actions:

 • Clearing some memory.

 • Deleting unnecessary files and closing apps running in the background.

 • Managing abnormal battery usage.

 • Scanning for crashed apps and malware

You can also save battery power by preventing apps that are running in the background from using battery 
power when they are not being used. Tick apps from the apps list on App power monitor and tap SAVE POWER.

Navigate to Settings > Tap Device Maintenance > Tap Battery > Tick Apps & Tap SAVE POWER

View Battery Usage data and optimize battery usage. Enable Optimize battery usage for individual apps. Some functions, such as those that use mobile networks or sync data, will be restricted to save battery power.

Navigate to Settings > Tap Device Maintenance > Tap Battery > Tap Battery Usage > Tap More icon (:) and Select Optimise Battery Usage

Check the using account lists on device and turn off auto-sync feature for the unused options.

Navigate to Settings > Cloud and accounts > Accounts > Disable 'Auto Sync Data'