Middle or large-sized battery pack assembly

A battery pack comprising:

• (a) a module assembly comprising two or more battery modules, each of which comprises a chargeable and dischargeable battery cell, the battery modules being stacked to have a two layer structure comprising an upper layer and a lower layer while being in contact with each other in a lateral direction;
• (b) a first upper layer connection member mounted at the upper layer module assembly to surround a portion of opposite sides and a front upper end of outermost battery modules of the upper layer module assembly, and a second upper layer connection member mounted at the upper layer module assembly to surround a portion of the opposite sides and a rear upper end of the outermost battery modules of the upper layer module assembly;
• (c) a first lower layer connection member mounted at the lower layer module assembly to surround a portion of opposite sides and a front lower end of outermost battery modules of the lower layer module assembly, and a second lower layer connection member mounted at the lower layer module assembly to surround a portion of the opposite sides and a rear lower end of the outermost battery modules of the lower layer module assembly;
• (d) a pair of side support members coupled to the upper layer connection members and the lower layer connection members to simultaneously surround sides of the upper and lower layer module assemblies;
• (e) insulation members mounted at interfaces between the sides of the upper and lower layer module assemblies and the side support members;
• and
• (f) a first lower end support member coupled to the side support members to support the front lower end of the lower layer module assembly, and a second lower end support member coupled to the side support members to support the rear lower end of the lower layer module assembly.