Power cell

A power cell was a type of energy source.

Cybermen
The second variant of Cyber-body used by the Cybermen of the Cyber Legions during the Cyber Wars of the 250th Millennium, (TV: Nightmare in Silver, PROSE: Ghost in the Machine) as well as numerous identical Cybermen across N-Space (TV: Dark Water, Death in Heaven et al.) and a parallel universe, (AUDIO: Code Silver) featured blue power cells, instead of the Cyber-chest packs and chest units used by previous Cyberman evolutions, (TV: The Tenth Planet et al.) or the chest plates used by the Cybusmen. (TV: Rise of the Cybermen, The Age of Steel, A Good Man Goes to War)

Other
TARDISes contained TARDIS power cells. (TV: Rise of the Cybermen)

Phason pods were a type of compressed power cells. (AUDIO: Daughter of the Gods)