Reset iPhone
Resetting your iPhone can correct multiple problems including signal strength and faulty battery indicators. Also, there are times when an application can consume battery power at a non-standard rate. When experiencing any issue with your iPhone try the power reset first. This can be accomplished by holding down the sleep and home buttons simultaneously until you see the Apple boot logo.
Drain the Battery Completely
The internal iPhone battery is just like any other rechargable battery. It's important that you completely change and discharge the battery during usage. This is considered a charge cycle and the full drain process will help optimize battery capacity. There are also studies that indicate full charge cycles will extend the life of the battery. The full charge and discharge is particularly important after you perform an
iPhone battery replacement.
Update to the Latest Software
Always make sure your iPhone has the latest software from Apple. Generally speaking, you can find battery performance and tuning enhancements in these updates. You can update your iPhone by using iTunes and select "Check for Updates" to see if there is a new version available. This is also recommended if you are experiencing any other functionality issues with your iPhone.
Minimize Use of Location Services
Applications that actively use location service such as Maps can reduce battery life. To disable lcoation services, go to Settings > General > Location Services.
Wi-Fi
The wireless Wi-Fi module in the iPhone is constantly seeking and evaluating the wireless signal around you for usage. This does impact battery life. If you know you won't we using Wi-Fi and are in a situation where preserving battery life is important, disable this setting. Wi-Fi can be disabled by going into Settings > Wi-Fi options. There is a slider to disable this feature. Note: The iPhone will remember the default wireless Access Point that was selected along with the security password as it is disabled. This makes it easier when it comes time to re-enable Wi-Fi.
Screen Brightness
The screen brightness setting will have a large impact on battery performance. We recommend this slider setting be position around the 1/4 area. This will provide for good brightness during indoor usage. This setting may need to be increased to 1/2 position for outdoor usage. There should be no need to increase the brightness above the 1/2 setting. The brightness setting can be found under Settings > Brightness option.
BlueTooth Wireless
The Bluetooth component on the iPhone allow the connection of wireless devices that are Bluetooth compatible. These are typicall headsets however wireless music peripherals are becoming more common. If your not using any of these features the Bluetooth component should be disabled to conserve battery life. This setting can be found under Settings > General > Bluetooth.
3G Radio
The iPhone has the capability of running either in the Edge or 3G data mode. The 3G mode provides for significently greater download speeds. These speeds can top 100kbps with a quality cell signal. However, the service availability is usually limited to larger population areas and it does create a greater draw on the battery. The Edge data network more widely available but is a much slower network. If your in an area that does not have 3G service you should disable the 3G radio on the iPhone. This can be disabled by going into Settings > General > Network. The 3G option slider will be at the top of the screen.
Push Mail
If you have a push mail account such as Yahoo!, MobileMe or Microsoft Exchange, turn off push mail when you don't need it. Go to Settings > Fetch New Data and set Push to Off. Message sent to your push email accounts will now be received on your phone based on the global Fetch setting rather than as they arrive. See Fetch eMail about above.
Mail Fetch
The iPhone has the capability to fetch emails from your POP service provider on a predetermined frequency. The fetch function also works when the phone is in standby mode. The more mailboxes and greater the fetch frequency the greater draw on the battery. Try and limit the number of mailboxes and reduce the fetch frequency. This setting can be found under Settings > Fetch New Data.
Use Airplane Mode in low or no Coverage Areas
Because your iPhone always tries to maintain a connection with the cellular network, it may use more power in low or no coverage areas. This can decrease battery life as it searches for the signal. Turning on Airplane Mode can increase battery life in these situations. Keep in mind when in Airplane Mode you cannot send or receive calls.
The introduction of the iPhone 3Gs has generated concerns around battery perfomance. Much of this concern has surfaced on Apple's 