NOVELTY - The assembly (10) has a container (14) e.g. support tray, housing a set of battery modules, where the container includes a base, a side wall (26) and three side walls extending from the base. A pressure release device e.g. rupture element (37), is arranged in the container for selectively allowing fluid such as gas, to escape beyond the container, where the pressure release device comprises scoring lines that rupture under high pressure conditions within the container. A potting material is placed in a case to partially encapsulate the modules.    USE - Battery pack assembly for a motor vehicle e.g. gasoline-electric hybrid vehicle and electric vehicle such as electric car.    ADVANTAGE - The assembly can activate the pressure release device placed in the container as pressure inside the assembly exceeds the normal or predetermined pressure, thus preventing escape of gases in to a passenger compartment of the vehicle to eliminate potential risk and any unwanted hazardous events to driver and/or passengers. The battery modules have excellent retention that surrounds and secures cells, and the electrode stack within the cell envelope from shifting. The potting material is placed in the case to partially encapsulate the modules, thus greatly reducing the potential permeation of liquids into the battery pack, or leakage from inside the battery module to the outside of the battery pack, thus preventing reduced product life or premature failures of the battery modules. The assembly includes polyurethane foam as a potential retention device, which is very competitive to that silicone or epoxy adhesives. The assembly utilizes the case that houses the modules and an encapsulant which locks the modules in position, and allows the assembly to be mounted in any orientation. The assembly reduces manufacturing costs due to simplified assembly methods. The assembly is simple in design and has a reduced mass.    DESCRIPTION OF DRAWING(S) - The drawing shows a perspective section view of a battery pack assembly with a cover removed showing a typical airflow path through the battery pack assembly and showing pressure release elements located on a base of a dish in an area inside a bridge.    Battery pack assembly (10)    Battery sub-packs (12)    Container (14)    Side wall (26)    Rupture element (37)