Abstract: A valve-regulated, deep-cycling, gas-recombinant, high energy, lead-acid battery operating at superambient temperatures and internal pressures wherein the sidewalls of the battery container (i.e., intersected by the intercell partitions) are abnormally thin and reinforced against bulging by ribs which project from the container and extend in a direction transverse the intercell partitions. The ribs will preferably have a sinuous shape for optimal strength and heat transfer from the battery.