Recently I came across the fact that in Ubuntu (at least in 12.10) there is no battery percentage when you click on the icon, it only displays the time left until it will run out. To fix this need I have, I have made an applet with the entire purpose of showing the percentage in the unity panel.
To install the applet, download the Github repo zip from this link
sudo chmod +x /path/to/dir/INSTALL.py sudo ./path/to/dir/INSTALL.py
After executing this, you should now be able to search for battery percentage in the dash and find the application as a blue icon with a battery and percentage icon.
Anyone who wants any changes made to this application can feel free to add an issue on the github repo