I'm having a really weird issue. My Galaxy S4 (i9500) is having a serious battery drain issue. As with most people, Google Play Services is the culprit. However, I noticed that it drains at a rate of about 6% per hour while I'm at work, but only 2% per hour when I'm at home.
I have the exact same WiFi access points at work than at home (D-Link 1155), and I honestly have no idea what else could affect it. See the screenshot here:
You can clearly see the moment I got home, the drain stopped. Yes, my screen has been on less than it was at work, but the screen still wasn't the cause of the battery drain at work.
Literally the ONLY difference I see between home and work, is the strength of the mobile network signal (see screenshot).