Some apps like...
Task Manager
Task Killer
Ram Booster
Anti Virus
Will cause your battery, you can remove all these apps which is not essential for an android device...
Also reduce sync interval for your accounts...
My battery runs flat too fast
Disable all data connections over mobile networks to save power when you’re not using the Internet. Doing so does not prevent your phone from transmitting data over other wireless networks.
Turn off GPS, Bluetooth™ and Wi-Fi® when you don’t need these features. You can turn them on and off more easily by adding the Quick settings widget to your Home screen.
Use Extended standby mode to minimise battery consumption when the screen is inactive.
Increase the synchronisation interval for your email, calendar and contacts.
Check the battery usage menu in the phone to see which applications use the most power.
Close and exit applications that you are not using.
Lower the screen brightness level.
Turn off your phone or activate Airplane mode if you are in an area with no network coverage. Otherwise, your phone repeatedly scans for available networks, and this consumes power.
Use an original headset from Sony™ to listen to music. A headset consumes less battery power than the phone’s loudspeakers.
Disable any live wallpaper.