Tubes of Transference

The Ark is equipped with Tubes of Transference which allow Transformers in one set of tubes to be re-energized by draining the remaining fuel from other Transformers in another set of tubes. The process is automated by the Ark's computer and involves thousands of wires and cables attaching themselves to the Autobots inside the tubes.

Fiction

Marvel The Transformers comics

As part of a last ditch effort of the energy deficient Autobots to defend themselves from an incoming assault by Decepticons, Optimus Prime ordered the Tubes of Transference be used on all of the functional Autobots except Ratchet to re-energize himself, Huffer, Ironhide, Bluestreak, and Mirage. The plan wouldn't have worked if not for Sparkplug Witwicky's sabotage efforts. The victory, however, was very short-lived. The Last Stand