A battery holder (25) holds a battery (27) in spaced relation to a printed circuit board (30), sufficient space (43) being provided between the printed circuit board (30) and the battery (27) for mounting of circuit components (47,49) on the printed circuit board (30) between the battery holder and the printed circuit board. A connection is provided between a connector (85) mounted on the printed circuit board (30) and a connector (82) mounted on leads (78) which are attached to the battery (27), the connection providing for the electrical connection and disconnection of the battery (27) and the printed circuit board (30). A housing (10) is provided for mounting the printed circuit board (30), battery holder (25) and battery (27) therein. The battery holder (25) is provided with a deformable retention clip (56) for retention of the battery (27) within a chamber (50,51) the holder (25), and in response to actuation by an operator, removal of the battery from the holder.