NOVELTY - An assembled battery system comprises at least two non-aqueous electrolyte secondary cells (101), where each secondary cell is installed in a parallelepiped cell case (102) and comprises a positive electrode (106) that occludes and emits lithium ions, a negative electrode (107) that occludes and emits lithium ions, and a non-aqueous electrolyte comprising an electrolyte dissolved in a non-aqueous solvent; and a cooling member is provided between the adjacent pair of the parallelepiped cell case, where the cooling member comprises an opening portion and an isolating wall.    USE - As assembled battery system (claimed) for electric automobiles and as cells for energy storage.    ADVANTAGE - The assembled battery system provides a cooling construction that can reduce temperature variation of each unit cell, and that can cool the non-aqueous electrolyte secondary cells with good efficiency.    DETAILED DESCRIPTION - An assembled battery system comprises at least two non-aqueous electrolyte secondary cells (101), where each secondary cell is installed in a parallelepiped cell case (102) and comprises a positive electrode (106) that occludes and emits lithium ions, a negative electrode (107) that occludes and emits lithium ions, and a non-aqueous electrolyte comprising an electrolyte dissolved in a non-aqueous solvent, where the non-aqueous electrolyte secondary cells are arranged so that each larger area side of an adjacent pair of the parallelepiped cell case faces in parallel to one another; and a cooling member is provided between the adjacent pair of the parallelepiped cell case, where the cooling member comprises an opening portion and an isolating wall, which define a cooling medium flow conduit between two larger area sides of the adjacent pair of the parallelepiped cell case.    DESCRIPTION OF DRAWING(S) - The figure shows the cross sectional structure of the non-aqueous electrolyte secondary cell.    Non-aqueous electrolyte secondary cells (101)    Parallelepiped cell case (102)    External positive terminal (103)    External negative terminal (104)    Electrolyte filling hole (105)    Positive electrode (106)    Negative electrode (107)    Separators (108)