In Sleep mode, WiFi feature is still running.
To save battery, switch off the WiFi feature before setting the device to Sleep mode.
- Tap on ‘Settings’.
- Under ‘Wireless & Network’, tap on ‘WiFi’.
- Tap the menu button at the top right corner.
- Tap on ‘Advance’.
- Tap on 'Keep WiFi on during sleep'
- Tap on 'Only when Plugged in'.