The Battery Mimic is an enemy in Final Fantasy XII found in the Barheim Passage. It eats the electricity that powers the route and if the electricity is completely gone, it gets pitch black and Zombies and Skull Defenders appear. When one is defeated, 30% of the power is recharged.
What a strange manner of creature, to so readily absorb the crackling power of electricity! Having absorbed an appropriate amount of nourishment from their feast of lightning, they discharge spectacularly, this being their primary form of excretion. Forgoing food of substance, their life-span is pitifully short.