When the battery charge level drops below 18%, the device displays a notice to connect the device to power. You should charge the battery using one of the charging accessories.
When the battery charge drops below 10%, the device displays a notice to connect the device to power. You must charge the battery using one of the charging accessories.
When the battery charge drops below 4%, the device turns off. You must charge the battery using one of the charging accessories.
To enable Battery Saver mode, swipe down from the Status bar and then touch Battery saver.