I have discovered battery drain and it is caused by GPS but I don't understand how is that possible when my location is turned off and location permission is denied for every app installed and also any app I use don't need gps. I don't have any unfamous or pirated apps installed, and didn't get any new apps since 5 days, and problem started today. So is there any way to see which app is using gps since here is just blank name..?
Go to setting--> Location
Then you will see list of recent apps who requested location. If you are still seeing apps there who is using location service then you can find which app is using your location service .
May be Google Play Services is the culprit here. It drains a battery a lot, infact it uses wifi scan in the background too!. So turning permissions off for it might help with the battery drain.
Whatever have happened here it is solved by rebooting phone (d'oh). I hate this way of solving bugs on R2D2's.
In the settings you can go to apps and there should be a menu where you can see which app has which permission, there you can click on location and you will see. Sincerely Rikvola