Accumulator/əˈkjuːmjəleɪtər/ Definition 1 of 4Pro Tip 1/2Energy Storage An accumulator often refers to a rechargeable battery used in various technologies. Don't forget to replace the accumulator in the flashlight. Pro Tip 2/2Charge Required The term implies that the device requires charging before it can provide power. The car won't start unless the accumulator has been charged.