VENT PLUG FOR LEAD-ACID BATTERY AND LEAD-ACID BATTERY

PROBLEM TO BE SOLVED: To provide a lead-acid battery having high reliability in which clogging of a porous filter arranged as a flame arrestor is suppressed and a pressure release valve arranged in parallel to the porous filter is stably operated, in the lead-acid battery; and to provide a vent plug of the lead-acid battery. SOLUTION: The inside of the vent plug fit to a liquid opening of the lead-acid battery is divided into four or more exhaust hoods communicating with each other by gaps, two opening parts are formed in the exhaust hood arranged beyond one or more exhaust hoods from the exhaust hood communicating with the battery, the porous filter is arranged to cover one opening part, an exhaust cylinder is formed in the other opening part, and a cap-like valve is fit to the tip of the exhaust cylinder. The opening area S of the opening part on the side facing the porous filter is limited to less than the bottom area D of the porous filter, and the opening area of the opening part corresponding to the exhaust cylinder is limited to the area smaller than an internal circumference area. COPYRIGHT: (C)2011,JPO&INPIT