Battery module assembly, battery pack, and device using battery as power source

A battery pack, comprising:

• a case;
• at least two battery module assemblies arranged in the case, each battery module assembly comprising:
• at least two battery modules arranged along a first direction, each of the battery modules comprising a plurality of battery cells, and a shell side wall of a battery cell comprising two oppositely arranged first side walls and two oppositely arranged second side walls, wherein an area of a first side wall is larger than that of a second side wall, and wherein the first side wall is perpendicular to the first direction;
• and
• a cooling plate arranged between two adjacent battery modules to perform heat exchange with the first side walls of the battery cells of the two adjacent battery modules,
• wherein the at least two battery module assemblies are arranged along a direction perpendicular to the first direction;
• and
• a connecting portion, disposed between and connecting two cooling plates corresponding to two adjacent battery module assemblies such that the cooling plates are connected by the connecting portion to form a cooling plate assembly having an integral structure,
• wherein the case comprises a separator beam fixedly connected to a case side wall and dividing internal space of the case into a plurality of subspaces,
• wherein the at least two battery module assemblies are respectively arranged in the plurality of subspaces,
• wherein the connecting portion is fixedly connected to the separator beam,
• wherein the case comprises a case cover and a case bottom respectively arranged at two ends of the case side wall along the first direction,
• wherein the case cover and the case bottom are detachably connected to the case side wall, and
• wherein the cooling plate assembly is positioned in the middle of the case side wall along the first direction, such that the cooling plate assembly, the case side wall, and the case cover form a space for accommodating battery modules on an upper layer, and the cooling plate assembly, the case side wall, and the case bottom form a space for accommodating the battery modules on a lower layer.