im not sure exactly but to help save battery power, turn off blue tooth, turn down brightness, make sure ur stopwatch isnt running, turn off location services for apps that you dont need, turn on autolock and set it for 1 minute, try not to use apps that run in background
When you have apps running in the background, they use up your battery life because they may not be in-use but they are still running. I have some games that require a lot of battery power (some need web access, some don't) so I always shut them down when I don't need them on. You should be able to shut them down by double-click home button, this brings up the apps all running in the background. Stuff you will probably need soon (mail, camera, etc) can be kept running but others should be shut down by holding your finger down on any app and when they wiggle tap the minus (be sure to swipe to the left to make sure you get them all).