Patent ID: 7511456
Filing Date: 2009-03-31
Classification: H01M,Y02E

Abstract:
1. A middle- or large-sized battery pack having a plurality of battery cells, which can be charged and discharged, stacked one on another with high density and electrically connected with each other, wherein the battery pack comprises, a lower case having an upper receiving part, in which the plurality of battery cells are successively stacked one on another as unit cells; an upper case having a lower receiving part, which covers the upper end of the unit stacked on the lower case; a first circuit unit for electrically connecting the stacked unit cells with each other, the first circuit unit having a sensing board assembly for detecting the voltage, the current, and/or the temperature of the battery and being located at the front of the battery pack in the displacement direction of electrode terminals of the unit cells; a second circuit unit electrically connected to the first circuit unit, the second circuit unit having a main board assembly for controlling the overall operation of the battery pack and being located in a lower receiving part of the lower case; and a third circuit unit electrically connected to the second circuit unit, the third circuit being connected to an external output terminal while preventing overcharge, overdischarge, and/or overcurrent and being located at the rear of the battery pack, wherein the upper case and the lower case of the battery pack are separated from each other; wherein at least one cable, which serves as the electrically connecting member, is arranged such that the cable extends along the thickness of at least one of the unit cells, whereby a tensile force is directly applied to the cable when the thickness of the battery cells (the unit cells) is changed; and wherein, a predetermined region of the cable, which can be disconnected by thickness increase of the battery cells, is located at one end (a) of opposite ends (a, b) of the battery cells, when the battery cells swell due to abnormal operation of the battery pack or degradation of the battery pack caused by the charge and discharge of the battery cells for a long period of time, the thickness of the battery cells is increased at the end (a), and stress is concentrated on the predetermined region of the cable, whereby the disconnection of the electrically connecting member is accomplished.