Stopper for closing filling hole of battery - has filter preventing acid droplets being carried to outside by evolved gases

摘要

The stopper consists of a tubular bush (1). The bush is closed (6) at one end and has a small hole (10) in that end. The bush is pushed into the filling hole of the battery and has a lip (4) that rests around the hole. A filtering substance (7) with numerous capillary channels fills the bottom half of the bush and is held in by a perforated olate (8). A plug fits into the top of the bush. The filtering substance removes acid droplets and water vapour from the gases leaving the battery and prevents them reaching the outside the corroding the battery casing. The substance may be filter paper, polyethylene granules, or porous plastics.