Abstract: A battery including a vent tower extending inwardly into the battery cell and terminating at a free end. A passageway is provided through the vent tower to allow the venting of gas. The vent tower includes a porous, hydrophobic filter in the passageway adjacent the free end of the vent tower, and a pressure-relief valve in the passage. The free end of the vent tower is spaced sufficiently from any wall of the battery casing that any void defined by a horizontal plane along the free end of the vent tower and the walls of the casing below the horizontal plane is greater than the volume of free electrolyte regardless of the orientation of the battery.