and positive terminals or posts 310 320 protrude from the top and side of the external battery housing so as to be external to the battery housing 10 and easily coupled to electrical connectors extending from the electrical system not shown this configuration accommodates the electrical connectors for common vehicle and equipment electrical systems variation in the placement the number and the type of possible posts or connections can be provided without departing from the inventive aspects of the instant invention one non limiting example of such a variation would be an exemplary embodiment providing internal connections to the common terminals for systems and vehicles in harsh environments the main positive output 110 and auxiliary positive output 210 are coupled to a switching device 300 which in turn selectively electrically couples in various operating positions the batteries 100 200 and their respective positive outputs 110 210 to the common positive terminal 310 based on various operating conditions and switch positions each operating position corresponds to different circuit configurations for coupling the main battery positive output 110 and auxiliary battery positive output 210 to the common positive output post or terminal 310 in the exemplary embodiment shown in fig1 5 switching device 300 is included in the housing it selectively electrically couples the main battery 100 or the auxiliary battery 200 to the electrical system additional embodiments can vary the number of operating positions or location and placement of the switching device 300 for instance in additional exemplary embodiments the switching device 300 may be included with an attachment or separate housing containing the circuitry and auxiliary battery 200 as discussed further in relation to fig6 and 7 herein.