A battery assembly includes a first battery frame assembly having a first plastic frame member and a first thermally conductive plate. The first plastic frame member has a rectangular ring-shaped peripheral wall and a plurality of cross-members. The battery assembly further includes a first thermally conductive plate having peripheral edges encapsulated within the first substantially rectangular ring-shaped peripheral wall. The plate further includes exposed portions configured to contact air passing through a first plurality of channels in the peripheral wall and past the first thermally conductive plate and through a second plurality of channels in the peripheral wall. The battery assembly further includes a first battery cell configured to contact the first thermally conductive plate.