Apparatus for controlling connection of battery pack

The present invention discloses an apparatus and method for controlling a connection between the parallel connection when the battery pack a plurality of battery packs. A plurality of battery packs connected to the control device in accordance with the present invention, is provided on the battery pack, each of the charging and discharging path switch unit for selectively opening and closing the charge and discharge path; A first control section that is provided in the battery pack, respectively, measured SOC of each battery pack, and controls the opening and closing of the switching part; And receives the SOC measurement value for each of the battery packs from the first control unit, grouping together a battery pack having a SOC value is within a predetermined error range, and the selection of the selection that contains the largest number of battery packs of the group, the group the battery pack to each other in parallel, the parallel connected battery pack in the after car SOC between to the parallel connected battery pack and the parallel unconnected battery pack to be charged or discharged in a position keeps within a predetermined range, that is not connected the parallel and a second control section that allows the battery pack is further connected to the parallel.