Apparatus and methodology for providing electronic access control are disclosed. In an exemplary configuration, a retrofittable electronic lock can be used to provide secure storage to an enclosure. A user interface and LCD visual display can be provided to permit convenient adjustment of system operational parameters. In certain embodiments, the electronic access control system includes master-slave control capabilities. In other embodiments, the electronic access control system includes inventory management capability. In still other embodiments, apparatus and methodologies provide the secure storage of the enclosure when the enclosure is being moved or otherwise transported from one location to another location. Various alternative arrangements may provide various alert features, as well as battery features which facilitate rapid replacement and/or reconfiguration.