Battery Pack and Holder

A battery pack, comprising:

• battery groups which are formed by stacking a plurality of battery cells each including a terminal surface having one side in a longitudinal direction including a positive electrode terminal and the other side in the longitudinal direction including a negative electrode terminal, and a pair of stacked surfaces adjacent to the terminal surface so that the terminal surfaces of the plurality of battery cells are directed in the same direction and the positive electrode terminal and the negative electrode terminal are alternately arranged, the stacked surfaces facing each other;
• and
• a holder which accommodates two or more kinds of electric components electrically connected to the battery groups and is disposed so that the electric components face a surface in which the positive electrode terminals and the negative electrode terminals of the battery groups are arranged,
• wherein the holder includes a load-side positive electrode terminal and a load-side negative electrode terminal to which a load is connected,
• the battery groups are constituted by a first battery group and a second battery group,
• arrangement of the positive electrode terminals and the negative electrode terminals of the first battery group is the same as that of the second battery group,
• the number of battery cells constituting the first battery group and the number of battery cells constituting the second battery group each are an even number,
• the battery pack further comprises an inter-group bus bar which electrically connects the first battery group and the second battery group to each other in series by connecting the positive electrode terminal and the negative electrode terminal of the battery cells disposed at one end of the first battery group and one end of the second battery group, respectively, in a stacking direction, to each other, the positive electrode terminal and the negative electrode terminal being adjacent to each other,
• a first inter-cell bus bar which electrically connects the battery cells constituting the first battery group to each other in series by connecting the positive electrode terminal and the negative electrode terminal of the adjacent battery cells in the first battery group to each other,
• a second inter-cell bus bar which electrically connects the battery cells constituting the second battery group to each other in series by connecting the positive electrode terminal and the negative electrode terminal of the adjacent battery cells in the second battery group to each other,
• a positive electrode-connection bus bar which is connected to the positive electrode terminal having a highest potential in the first battery group and the second battery group which are electrically connected to each other in series, and
• a negative electrode-connection bus bar which is connected to the negative electrode terminal having a lowest potential in the first battery group and the second battery group which are electrically connected to each other in series, and
• the positive electrode-connection bus bar and the negative electrode-connection bus bar are connected to the holder.