NOVELTY - The battery module has battery group which includes battery columns with first battery column and second battery column. A connection terminal portion is coupled with terminal planes of the battery cells, and a coupling portion (91R) has first coupling portion (91R1) coupled with the first battery column and second coupling portion (91R2) coupled with the second battery column. A center of extension starting end of the extension portion (91R3) is between a first position of horizontal distance L divide by 12 on a first side of the first coupling portion from the centerline.    USE - Battery module for power storage device for power storage system for electronic appliance and electric vehicle (all claimed).    ADVANTAGE - Allows the voltage of the battery cells to be detected more accurately. Allows the communication unit to conduct bidirectional communication since the control signal is received from the control box through the communication terminal. Provides power storage device which is capable of easy and efficient assembly and achieves high energy due to space reduction. Increases the safety and improves the operability by conducting the setting operation from the outside of the exterior case. Improves the energy density of the power storage device since a larger number of battery cells can be housed in the limited space of the battery case. Suppresses the deformation of the battery cells since the load applied from the upper battery cell and lower battery cell can be reduced and the pressure and stress can be dispersed.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a power storage system;    (2) an electronic appliance;    (3) an electric vehicle;    (4) a power system; and    (5) a connection terminal.    DESCRIPTION OF DRAWING(S) - The drawing shows plan views of the connection terminal portion.    Coupling portion (91R)    First coupling portion (91R1)    Second coupling portion (91R2)    Extension portion (91R3)    Holes (96)