Hold MENU, and select Settings > Power Manager.

Battery Saver

Customizes system settings to extend battery life in watch mode (Customizing the Battery Saver Feature).

Power Modes

Customizes system settings, activity settings, and GPS settings to extend battery life during an activity (Customizing Power Modes).

Battery Percentage

Displays remaining battery life as a percentage.

Battery Estimates

Displays remaining battery life as an estimated number of days or hours.