Lead-Acid Battery: Post Seals for the New Bell System Battery

The posts on all lead-acid batteries are sealed to prevent the escape of sulfuric acid electrolyte from the battery container. If this highly corrosive aqueous solution of sulfuric acid escaped, it would constitute a hazard and a nuisance in a central office. Electrolyte leaking from the seal of a post can create a high conductivity path to ground. This path, connected to the battery, can lead to heating and arcing which may result in the ignition and burning of adjacent combustible materials. In addition, batteries with leaking post seals require costly periodic maintenance. Leaked electrolyte must be cleaned up, neutralized and replaced. The post seals of many batteries in float operation leak after being in service for times which are incompatible with Bell System objectives of reliable component performance for twenty to forty years. In this paper, we describe a post sealing system which is developed to be compatible with the expected long-lived behavior of the other components of the new Bell System battery. Post seals (there are three types) on batteries currently in telephone plant have at least two features in common: (i) They exert circumferential pressure 011 the post to make the seal. (it) They have seal lengths of less than one-half inch. One type of seal is flexible so as to accommodate motion of the post, relative to 1405