That sounds like a huge battery drain.
The Battery Manager will let you query for charging status, but you still need a context. Since you're instantiating this in the Application class, that works out for you.
Edit: just noticed that you'd already read the guide. Look at this section, and remember that the application itself is a valid context:
final IntentFilter ifilter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
Intent batteryStatus = this.registerReceiver(null, ifilter);
int level = batteryStatus.getIntExtra(BatteryManager.EXTRA_LEVEL, -1);