Please follow steps below for troubleshooting：
Activate Power Saver
Enable Smart saving and select your preferred mode in Settings > Power management > Power saver
*Ultra-saving mode is recommended when other modes do not meet your requirement
Please be noted this mode disconnects network connection when the device is suspended
Disable connection that are not used
Disable connection that are not currently used, such as Wi-Fi, location, network data usage, WiFi hotspot, Bluetooth, GPS
When WiFi and 3G network are both available, use WiFi for first priority
Steps：Slide down the screen from upper area to access Quick settings and disable those functions
Close background apps
- Tap recent apps key and perform "Clear All"
- Slide down the screen from upper area to access Quick settings and tap "Boost"
- Check "Battery used by app" and "Keep awake" status in Settings > Power management > Power Consumption Table and close those apps that drain battery quickly
Disable auto-sync and auto-update
- Google account：Disable individual sync function in Settings > Google > Accounts
- Play Store：Open Play Store > tap upper-left menu icon > Settings > Auto-update apps > Do not auto-update apps
- Data usage：Settings > Data usage > upper-right menu icon > disable Auto-sync data
- Google Now cards：Settings > Google > Search > Now cards > turn off Show cards
Others
- Adjust brightness of display in Settings > Display > Brightness
- Close live wallpaper
Tap and hold home screen (to access home screen management) and then tap Wallpapers for settings
- Adjust device sleep time in Settings > Display > Sleep
- Disable Auto-rotate screen in Settings > Display
- Use darker wallpaper
- Remove widgets that are not used on home screen
- Restart device
