Get a BroadcastReceiver to outlive it's Activity
===

I work on an Android app, what should simply post some information about the battery in the notification-bar. I started this project like all the tutorials advised:

 - I created a BroadcastReceiver. It handles the UI stuff.
 - Then i created an IntentFilter, what filters only the
   ACTION_BATTERY_CHANGED intents
 - Then i simply registered the IntentFilter and the BroadcastReceiver instances
   with the registerReceiver() method of my main Activity.

It works really fine, until the Activity (what registered the two) stops. By stoping i mean, i press the back button on the phone, and i assume the onStop() or/and onDestroy() methods get called. 

My question is, how could i get the BroadcastReceiver to run after the Activity is finished, and only stop recieving, when i 'Force close' the app?