The present disclosure relates to the manufacture of battery packs/assemblies and more specifically, the manufacture of battery packs/assemblies for use in aircraft. A lightweight battery assembly with cell compression and/or pressure management system is disclosed herein. The battery assembly can employ a composite battery enclosure impregnated with a plurality of primary fibers that define a direction of the composite battery enclosure's tensile strength. A cell-stack can be positioned in the composite battery enclosure such that the composite battery enclosure applies a predetermined pressure upon the cell-stack to compress the cell-stack in the direction of the composite battery enclosure's tensile strength.