A battery system includes an enclosure having opposed first and second major walls, a perimetral wall connecting the first and second major walls along respective perimeters thereof, and an interior defined by the first and second major walls and the perimetral wall, wherein the enclosure is configured for containing an anode assembly, a cathode assembly and an electrolyte within the interior. A longitudinal embossment is formed in the perimetral wall extending outward from the interior and extending along opposed adjacent portions of the first and second perimeters. A wall port is defined in the perimetral wall in fluid communication with the interior, wherein the wall port is configured for permitting flow of the electrolyte therethrough into and out of the interior. First and second electrodes extend through the perimetral wall and are configured for electrical connection with the anode assembly and cathode assembly, respectively.