Supervolt

The Supervolt company was known to produce lightsaber power cells. At least one Sith, Darth Vader, was known to use the Supervolt batteries in his lightsaber.

However, these power cells were known to short out easily, as Vader's did while he was dueling the Energizer Bunny. This led to the Energizer Bunny's victory over Vader as Vader cried out in anguish.

Text and facts from the “Supervolt” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.