The truth is, these task managers and Android work against each other. Task killers are redundant, unnecessary and typically cause more harm than good. Yes, this goes against all that you have been told as an Android user; they seem like they’re helping. This is called a placebo effect. So why are these app managers bad? How do they actually cause harm? Unlike a PC where you must manage memory yourself by closing programs, the Android OS (2.2 and above) is meant to manage memory and processes on its own. Let’s say the user launches an application. This app will then stay in memory until it absolutely needs to be closed. This is done to improve application launch time; the app will “run” in the background – leaving battery and performance essentially unaffected – ready to be launched again at any moment. If a previously launched application is kept in memory, launching it again at a later time will take much less time. Killing the app removes it from memory and will slow down the application launch next time you need it. Android will automatically begin closing applications as needed, starting with the ones that have been inactive for the longest. Now that we have that out of the way, you can kill the app using the “force stop” feature is built into Android itself, effectively making any third-party task managers pointless. This all means that the use of a task killer does, in fact, have a negative effect on your phone’s battery life. If you are constantly shutting down apps manually then the system is never merely putting apps to sleep, but it constantly shutting down and reopening apps. It also means that the system will never be able to properly learn your app usage habits and ultimately your battery life will suffer. If you are using a task killer app then I highly recommend you uninstall it immediately. Once you’ve done that then you will have to wait a few weeks before your phone has learned more about how you use your apps before you will see a noticeable difference in the length of time you can use your phone before needing to charge it. In the end, however, it is definitely worth it. Task killer apps and battery manager apps can also effect connectivity settings/permissions installed by your carrier specifications/software/firmware on the device and can be easily fixed by a master reset or restoring to factory settings. So that’s it – if you’re running Android 2.2 or above then do not use a task killer/battery manager and completing a master reset/factory restore if they were installed will resolve unseen issues . Great link for more info http://android-developers.blogspot.com/