Android app force closes on a real device but works on the emulator

[Monique7]

Hi, My app has an action bar with tabs with 3 fragments (1-list fragment with the list of running processes, 2-battery and memory info, 3-just some text). It works fine, with no errors on the emulator, but on a my phone it starts ok, I go through the tabs several times(I left the phone to go into sleep mode and back and the app still worked) and then it unexpectedly force closes.
I'm new to Android and I don't know how to correct these errors, Please help me!

Here are the logcat errors and the code for the Battery class:

05-15 07:24:30.809: E/AndroidRuntime(25883): FATAL EXCEPTION: main
05-15 07:24:30.809: E/AndroidRuntime(25883): java.lang.RuntimeException: Error receiving broadcast Intent { act=android.intent.action.BATTERY_CHANGED flg=0x60000010 (has extras) } in [email protected]
05-15 07:24:30.809: E/AndroidRuntime(25883):     at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:755)
05-15 07:24:30.809: E/AndroidRuntime(25883):     at android.os.Handler.handleCallback(Handler.java:605)
05-15 07:24:30.809: E/AndroidRuntime(25883):     at android.os.Handler.dispatchMessage(Handler.java:92)
05-15 07:24:30.809: E/AndroidRuntime(25883):     at android.os.Looper.loop(Looper.java:154)
05-15 07:24:30.809: E/AndroidRuntime(25883):     at android.app.ActivityThread.main(ActivityThread.java:4624)
05-15 07:24:30.809: E/AndroidRuntime(25883):     at java.lang.reflect.Method.invokeNative(Native Method)
05-15 07:24:30.809: E/AndroidRuntime(25883):     at java.lang.reflect.Method.invoke(Method.java:511)
05-15 07:24:30.809: E/AndroidRuntime(25883):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:809)
05-15 07:24:30.809: E/AndroidRuntime(25883):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:576)
05-15 07:24:30.809: E/AndroidRuntime(25883):     at dalvik.system.NativeStart.main(Native Method)
05-15 07:24:30.809: E/AndroidRuntime(25883): Caused by: java.lang.NullPointerException
05-15 07:24:30.809: E/AndroidRuntime(25883):     at com.example.mytaskmanager.Battery.setare(Battery.java:77)
05-15 07:24:30.809: E/AndroidRuntime(25883):     at com.example.mytaskmanager.Battery$1.onReceive(Battery.java:120)
05-15 07:24:30.809: E/AndroidRuntime(25883):     at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:746)
05-15 07:24:30.809: E/AndroidRuntime(25883):     ... 9 more