This was an unexpected surprise. Ruby was running fine until all of a sudden she wouldn't start. Even after many jumpstarts, she would still stop running after approximately 30 seconds. At that point I had to determine if the generator wasn't working, or if the battery had something wrong with it.
After a quick inspection of the battery, I could see that the terminals were loose. When tightening them didn't work, I pulled the battery out to charge, and to look at the terminals. The positive terminal needed to be replaced to be tightened. Quick replacement later and Ruby was back up and running.