Patent ID: 8080332

Claim:
A battery pack comprising: a roughly rectangular casing including support protrusions extending from a bottom surface of the case into an interior of the case; a partition member that supports cylindrical battery cells, the partition member being supported by the support protrusions; a main circuit board disposed in the interior of the case and at the bottom surface of said casing, the main circuit board including holes having a greater diameter than a diameter of the support protrusions, the support protrusions extending from the bottom of the case through the holes in the main circuit board to the partition member; and the cylindrical battery cells arranged in two rows and two layers over said main circuit board and connected in series, said cells including: a first battery cell having a positive electrode terminal disposed in the vicinity of a positive electrode terminal connection part of said main circuit board provided with said positive electrode terminal connection part on one side and with a negative electrode terminal connection part on the other side; a second battery cell disposed over said first battery cell in the state of having a negative electrode terminal directed to the side to which a positive electrode terminal of said first battery cell is directed; a third battery cell having a negative electrode terminal disposed at said negative electrode terminal connection part of said main circuit board; a fourth battery cell disposed over said third battery cell in the state of having a positive electrode terminal directed to the side to which said negative electrode terminal of said third battery cell is directed; said positive electrode terminal connection part of said main circuit board and said positive electrode terminal of said first battery cell being electrically connected to each other through a first electrode tab; a negative electrode terminal of said first battery cell and a positive electrode terminal of said second battery cell being electrically connected to each other through a second electrode tab; a negative electrode terminal of said second battery cell and a positive electrode terminal of said fourth battery cell being electrically connected to each other through a third electrode tab; a positive electrode terminal of said third battery cell and a negative electrode terminal of said fourth battery cell being electrically connected to each other through a fourth electrode tab; and said negative electrode terminal of said fourth battery cell and said negative electrode terminal connection part of said main circuit board being electrically connected to each other through a fifth electrode tab.