When you're running low on juice, you can squeeze more endurance out of your S4 by turning off automatic account syncing. Doing this will tell your phone not to update email, Facebook and other data in the background. Just swipe down from the top of the screen and tap the Sync button in the Quick Settings menu if it’s green.
To disable automatic app updates, enter Google Play and press the Settings button. Then press the Auto-Update Apps button and choose the “Do not auto-update apps” option.