In certain embodiments, an apparatus comprises a battery housing and mechanical switches. The battery housing is configured to house one or more batteries and comprises a connector configured to provide current to a device. A surface of the battery housing forms slots, where each slot is configured to receive a battery. Each mechanical switch is coupled to a slot and is configured to allow current from the battery to flow to the connector if a battery is received in the slot, and to pass current through the slot if a battery is not received in the slot.