The Battery use screen allows you to see which apps are consuming the most battery power. Information on this screen allows you to identify downloaded apps you may want to turn off when not being used, so you can get the most out of your battery power.
From the Home screen, touch and hold the Recent Apps Key (in the Touch Keys bar) > Settings > About phone > Battery > Battery use.
OR
From the Home screen, touch and hold the Recent Apps Key (in the Touch Keys bar) > Settings > Battery, then tap the Battery icon (at the top of the screen).
The top of the Battery use screen displays a usage graph and below it, battery usage times. It lists all of the apps or services using battery power from the greatest amount of energy used to the least amount.
Tap an app or service in the Battery use screen to see the details about its power consumption, including either how long since last connected to a power source or how long you were last running on battery power. Different apps or services offer different kinds of information, and they may even include options to modify the settings so you can reduce power consumption by that app (or stop running the app).