One major disadvantage of the Wi-Fi is excessive battery drain which makes its users to be very conscious about the usage of the Wi-Fi. For the Android users, who prefer to remain connected with the Wi-Fi for a longer span of time, Android has a feature which enables the optimized usage of the battery when your Android device is connected to the Wi-Fi. If this feature is opted, the Android applies the state of the art technology to use minimum battery to run Wi-Fi and saves a lot of battery for the other functions of the Android device.
If you want to get benefit from this feature of battery optimization, the instructions may help you.
Instruction
Command Line: Settings – HOME > Wi-Fi –WIRELESS & NETWORKS > Settings Popup Menu Button > Advanced > Wi-Fi optimization.
1: Tap the icon of ‘Settings’ on the HOME screen of your Android 4.4.4 KitKat device to open up the ‘Settings’ screen. 
2: Tap the ‘Wi-Fi’ in the WIRELESS & NETWORKS’ section. 
3: At the ‘Wi-Fi’ screen, tap the ‘Settings’ button, given at the bottom right corner of the screen. It will open up a popup menu. 
4: Tap the ‘Advanced’ in the ‘Settings’ popup menu.
5: At the ‘Advanced Wi-Fi’ settings screen, see the ‘Wi-Fi optimization – Minimum battery usage when Wi-Fi is on’ is not checked, i.e. disabled. 
6: Tap the ‘Wi-Fi optimization – …………. ‘ to activate and enable this feature. 
From now onward, the Android will use your battery, carefully and scientifically, while the Wi-Fi is connected. Now, you may remain connected with Wi-Fi for a longer period of time as the responsibility of battery optimization is shifted, to some extent, to the Android.
That’s all!