POLAR COLUMN OR LEAD-ACID BATTERY AND MANUFACTURE THEREOF

PURPOSE:To improve the current-carrying performance of a polar column for a lead-acid battery by providing a tin-plating layer through a lead-plating layer in the surface of a bolt or a nut to improve adhesion between the polar column main body and the bolt or the nut. CONSTITUTION:In a polar column for a lead-acid battery, a tin-plating layer 3 is provided through a lead-plating layer 2 in the surface of a nut 1 containing copper as a main component. The base body of the nut 1 with the lead-plating layer 2 and the tin-plating layer 3 has the structure of being cast into a polar column main body containing lead as a main component. The nut l has a buried base part 1a at the base end and the tin-plating layer 3 is applied to the surface of the buried base part 1a through the lead-plating layer 2. The length cast into the polar column main body becomes long, so that the mechanical coupling strength and the current-carrying performance between the bolt or the nut and the polar column main body 4 are remarkably improved.