Battery indicator has disappeared from Gnome panel

Note: Try steps 4/5 first, it may be fixed with 1st hit.

Below the extended instruction to debug the problem with the indicator.

1. Check if indicator-power-service is running:

   ps ax | grep indicator-power
   

2. If it's running, try reset its settings then restart it:

   dconf reset -f /com/canonical/indicator/power/
   pkill -f indicator-power-service
   

   No success, locate it then try it from terminal (looking for any errors in output):

   sudo updatedb; locate -r indicator-power-service$
   

   My system is 64bit, So:

   /usr/lib/x86_64-linux-gnu/indicator-power/indicator-power-service
   

   If it works with command, then some thing wrong with its autostart.

3. As it was checked, it isn't running on start up. Verify the existence of:

   /usr/share/upstart/sessions/indicator-power.conf

   description "Indicator Power Backend"
   
   # Want to move to indicator-services-[start|end], but that's not all
   # there yet.  Use the signals that exist today for now.
   
   start on indicators-loaded or indicator-services-start
   stop on desktop-end or indicator-services-end
   
   respawn
   
   exec /usr/lib/x86_64-linux-gnu/indicator-power/indicator-power-service
   

   /etc/xdg/autostart/indicator-power.desktop

   [Desktop Entry]
   Type=Application
   Name=Indicator Power
   Exec=/usr/lib/x86_64-linux-gnu/indicator-power/indicator-power-service
   NotShowIn=Unity;
   NoDisplay=true
   StartupNotify=false
   Terminal=false
   

4. This works for me with a fresh Ubuntu 14.04, Modifing indicator-power.desktop for autostart conditions similar to the other indicators. (Submitted bug report lp#1330302)

   sudo nano /etc/xdg/autostart/indicator-power.desktop

   Remove:

   NotShowIn=Unity;
   

   Replace it with:

   OnlyShowIn=Unity;XFCE;GNOME;
   AutostartCondition=GNOME3 unless-session gnome
   

5. Logout/Login

---

Well if it didn't work:

1. Try purge it then reinstall it:

   sudo apt-get remove --purge indicator-power
   sudo apt-get install indicator-power
   

   Reboot, Check again

2. No success, as workaround you can run it this way (you may close terminal after this):

   /usr/lib/x86_64-linux-gnu/indicator-power/indicator-power-service & disown $!
   

   & run it in background
   disown $! command to detach a process for current terminal, $! variable that hold PID of last process run in background

   Or better if add it to user startup applications, see How do I start applications automatically on login?

(1)

sudo apt-get install indicator-applet-complete
sudo apt-get install dconf-editor

change icon-policy to present. This might help you.

(2)

If first one do not work you can try to install indicator-power by sudo apt-get install indicator-power. If indicator-power is already install then uninstall it and then reinstall. This might get the power indicator back on the panel. Have fun.