How to save battery life in andriod

>Turn off hotword detection

 Go to “Google app -> Settings -> Voice -> “Ok Google” hotword detection -> OFF”.
>If you are not a great fan of Google Now, it is best that you turn off the complete service
 from “Google app -> Settings -> Google Now -> OFF”. Select the “Also turn off Location History” box and tap the “Turn Off” option.
>Adjust Location mode
 Go to “Settings -> Location -> Mode”, and you’ll see that there are three modes: High accuracy, 
which uses GPS, WI-Fi, and mobile networks to determine location.
>Enable Android Run Time (ART)
 Go to “Settings -> About phone,” and repeatedly tap “Build number” until it says “you are a developer.”
> This will turn on the Developer Mode. Now, come back to the previous menu, and you’ll see
 “Developer options” just above the “About phone” option.
>Once inside the “Developer options” menu, tap the “Select runtime” and select “Use ART.”
Your phone will reboot and the whole conversion process will take ten to twenty minutes.
>Turn off auto-sync and always-on Wi-Fi scanning

While not exclusive to Android KitKat, there are a couple of more useful tricks that you can use to boost your phone’s battery life. The first is the auto-sync feature that assumes you’d like to sync everything including Calendar, Contacts, Keep, Photos, and more. As you can see, Google syncs a lot of stuff which in turn seriously affects your phone’s battery.

>To disable auto sync, head to “Settings -> Google -> [tap your account]” , and disable 
the services you don’t want Google to sync.
>Did you know that your phone scans for Wi-Fi connections even if you’ve turned off the Wi-Fi option? 
Yes, that’s true, and the reason is that it helps apps, games, and Google Play pinpoint your phone’s location.This, again, negatively impacts your phone’s battery. 
>To disable this feature, head to “Settings -> Wi-Fi -> Advanced”, and turn off the “Scanning always available”
 feature.