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Siress Belloby's energizer (TOS: "The Magnificent Warriors").

Energizers are electrical generators.

Commander Adama made plans to trade an older unmarked energizer on the planet Sectar in exchange for agro seed (TOS: "The Magnificent Warriors").

During a Cylon attack, energizer #1 is knocked out on Galactica, complicating firefighting efforts as well as critical surgery needed by Commander Adama (TOS: "Fire in Space").

Galactica 1980

Energizers provide power to the invisibility screens Doctor Zee created and outfitted on Colonial Vipers. Dillon voices his concern over needing to recharge such energizers in their craft during their brief incarceration at a police station (1980: "Galactica Discovers Earth, Part I"); a fully charged energizer can last for about 24 hours Earth time when the invisibility field is activated (1980: "Galactica Discovers Earth, Part II").