So I wanted to get a percentage of battery remaining instead of time remaining, and tried the solution in Can I set the power indicator to show battery percentage instead of time remaining?.
sudo apt-get install battery-stats
But then when I went to my panel, I found I could no longer add new instances of Power Manager Plugin to my panel or Notificaion Area items. Both the items were greyed out and when I selected them, I could not click add. I then ran:
sudo apt-get remove battery-stats
But that did not fix things. I'm not sure if installing the battery stats thing was the cause of my problem, I only discovered this problem right after installing it.
I'm running XUbuntu 16.04.