Abstract: A battery vent plug providing repeated relief of a pressure condition within a battery at relatively low internal pressures. The vent plug is arranged to prevent dropping of the internal pressure to zero upon venting while yet having a small relief-reseal pressure range. The vent plug includes a relief valve within a housing defined by a rubber cylinder releasably engaging an annular seat on the housing about an inlet to a vent chamber within the housing. The rubber cylinder is maintained under a preselected compression assuring sealing thereof to the seat at pressures below a preselected venting pressure. Upon removal of the sealing portion of the cylinder from the seat, the pressurized gas escapes around the cylinder and through a hole in the housing to atmosphere.