Cosmic Energy Cell (5e Equipment)
From D&D Wiki
A cosmic energy cell is a far more advanced form of a common energy cell. In terms of energy storage, it is exponentially more powerful. Equipment which normally runs off of power cells can use cosmic energy cells, in which case they effectively never need to be reloaded or recharged - the drain on the cosmic power cell is so insignificant as to be non-measurable. Some awesomely powerful artifacts only use cosmic energy cells, expending shots, strikes, or charges as normal. Even among the majority of starfaring civilizations, such powerful and compact energy sources only exist in myth and legend.
Weight: 5 oz.