Mega-condensers are highly specialized components used for vehicles. Perhaps required for spaceships, the exact purpose is unknown, but at least two mega-condensers are known to exist:
In Feliner, Part 1, Panthro mentions needing a mega-condenser in order to finish the Feliner. Snarf suggests that the Ratstar might have one, which Panthro agrees is a good idea. Thus, in Feliner, Part 2, the ThunderCats attempt to track down the Ratstar's mega-condenser.
Mumm-Ra absconds with the device before the ThunderCats arrive, but eventually Lion-O tracks it down and takes possession of it.
In a later episode it is revealed that the ThunderTank has a mega-condenser as well.
- Snarf refers to it as "mega-dingus"
- ThunderCats outtakes include the Lion-O voice actor Larry Kenney struggling with the line: "Let's find the mega-condenser".