An apparatus for delivering electrical power to an electrically powered medical device includes a battery, a first compartment, and a second compartment where the second compartment can hold the first compartment and the first compartment can hold the battery. A sterile space is defined between the first compartment and the second compartment. The first compartment and the battery may be selectively electrically coupled with the electrically powered medical device such that the first compartment does not compromise the sterility of the electrically powered medical device.