A battery is a device with two or more connected cells that produce a direct current by converting chemical energy into electrical energy.

They are used on spacecraft as a means of power storage. Primary batteries contain all their usable energy when assembled and can only be discharged. Secondary batteries can be recharged from some other energy source, such as solar panels or radioisotope-based power (RTG), and can deliver power during periods when the space vehicle is out of direct sunlight. Batteries generate electrical current from a chemical reaction.

Batteries for spacecraft must be sealed to operate in vacuum. They must withstand the acceleration of launch, and vibration while attaining orbit. They must be able to operate over a wide temperature range and must not emit gases that would corrode the space vehicle, disturb its trajectory, or contaminate instruments or life support systems.

Batteries for vehicles orbiting the Earth must also resist the high ionizing radiation level above the shield of the Earth’s atmosphere. Artificial satellites, such as communication satellites, require battery systems that can withstand thousands of charge and discharge cycles over the satellite’s intended life.