Battery pack

A battery pack comprising:

• a plurality of battery cells arranged in rows that are parallel with a first axis, wherein the battery cells arranged in the rows adjacent to each other in a second axis crossing the first axis are forwardly or backwardly misaligned with each other with respect to the first axis such that the battery cells of alternating rows are aligned in columns along the second axis;
• and
• a plurality of bus bars having a zigzag shape and forming a plurality of parallel modules by connecting corresponding ones of the battery cells arranged in the second axis in parallel and the battery cells in each row along the first axis are connected in series,
• wherein a bus bar from among the bus bars that is at an edge comprises:
• a first contact side;
• a second contact side;
• and
• a third contact side,
• wherein the first contact side, the second contact side, and the third contact side are respectively arranged on and elongated along a first line at a first side of a column of the battery cells, a second line at a central region of the column of the battery cells, and a third line at a second side of the column of the battery cells, that are parallel with the second axis and spaced apart from each other along the first axis, and
• the first, second, and third contact sides are located at an end region of the bus bar along the second axis, and the third contact side is not located at the central region of the column of the battery cells wherein the first through third lines are sequentially located in the order of a forward location then a backward location with respect to the first axis, and the first through third contact sides are sequentially arranged in the order of the forward location then the backward location with respect to the first axis.