A group of rechargeable batteries held within a holder or container intended to provide temporary electrical energy to operate a medical device, typically when it is not possible, intentional, or convenient to connect the device being powered to a mains electricity (AC-powered) electrical outlet. It is typically used during a transport situation (e.g., a neonatal incubator), or when the device is designed to power a cordless devices (e.g., an endoscopic device or a rechargeable battery-powered surgical drilling system handpiece). This is a reusable device.