Provided herein are battery packs comprising a first polymeric endplate, a second polymeric endplate, and a plurality (n) of partitions extending between the first endplate and second endplate and defining (n−1) battery cavities. Each cavity is capable of receiving a battery cell stack comprising a plurality of battery cells and optionally cooling plates and foam pads. Partitions comprise a plurality of polymeric repeating spacers, and each spacer from each partition can correspond to a cooling plate common to a plurality of battery cell stacks. Each of the repeating spacers and cooling plates can include a plurality of aligned apertures, and corresponding bolts can occupy the aligned apertures and secure the same to the endplates. Each repeating spacer can correspond to a complete or partial battery unit, wherein a complete battery unit comprises a first battery cell, a cooling plate, a second battery cell, and a foam pad.