From BlackBerry.Com
Extend battery life
Try performing the following actions:
Set your BlackBerry® device to turn on and turn off automatically.
Charge your device regularly.
Keep your battery connections clean. Every few months, use a cotton swab or dry cloth to clean the metal contacts on the battery and the device.
Set backlighting to remain on for a shorter period of time and lower its brightness.
Turn off the connection to a wireless network when you are not in a wireless coverage area.
Switch your vibrating notifications to sound notifications or LED notifications, lower the volume of your sound notifications, or select a shorter ring tone.
Delete the original message when you send a reply.
Send a message to multiple contacts using Add To, Add Cc, or Add Bcc.
Turn off the flash in the camera.
Close third-party applications from the application menu when you are finished with them.
Change your browser options for animated graphics so that they repeat less often on web pages.
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