How to Conserve iPhone battery life
The iPhone truly is a computer that fits in your pocket. The device sends email, browses the Internet and lets you play a variety of games. All of these features, however, reduce the battery life of the iPhone. The battery life determines the amount of time the iPhone runs before it needs charging. To extend the battery life on your iPhone as much as possible, follow a few simple rules.
Keep your iPhone out of extreme heat and cold. According to Apple, heat is the factor most likely to reduce the battery life of your iPhone. Never let your iPhone sit in temperatures that exceed 113 degrees Fahrenheit. Try to keep the phone's temperature between 32 and 95 degrees Fahrenheit at all times.
Turn off location services and push notifications when you are not actively using them. Location services let your iPhone access your GPS coordinates when you're mapping directions or checking in with an application like Facebook. Push notifications let applications notify you of new events, such as when it is your turn in a game. Both location services and push notifications cause your iPhone to burn battery power. Turn them off using the "Settings" application.
Fetch new emails less often. Your iPhone can check for new incoming emails as frequently as every 15 minutes. Each time your device looks for new email, it expends battery life. Set the iPhone Mail app to check for new emails less frequently to conserve battery life.
Minimize the use of graphics-intensive apps when you need to conserve battery life. If you minimize the amount of time spent playing games or using other applications, the screen on your iPhone will be able to dim more often, allowing the device to go into rest mode. Even applications that do not require an Internet connection still deplete the battery.
Turn off the Internet when you are not actively using it. By default, the iPhone always has the 3G network running. Go to the "Settings" application, select "Network" and disable the 3G network to conserve battery life. Use Wi-Fi Internet whenever possible; Wi-Fi may be slower but often uses less battery life. You can also turn off Wi-Fi using the "Settings" application.
Reduce the screen brightness on the iPhone. Go to the "Settings" menu and slide the "Brightness" bar to the left. Dimming the backlight on your device uses less battery than running it at full brightness.