Abstract: A battery pack assembly is provided for supplying electrical power to an electronic device, such as an electronic receiver of an animal confinement system. The battery pack assembly is removably insertable within a receptacle of the electronic receiver to electrically connect a battery contained within the battery pack assembly to internal electronics of the electronic receiver. The battery pack assembly includes a battery housing having an open end and a closed end. A pair of contact members electrically contact one terminal of the battery adjacent the open end and provide electrical contact with the one terminal of the battery from outside the battery housing adjacent the closed end. A flexible contact member, such as a spring, electrically contacts the opposite terminal of the battery adjacent the closed end and provides electrical contact with the opposite terminal of the battery from outside the battery housing adjacent the closed end. The flexible contact member biases the battery toward the open end.