USE OF SECONDARY LEAD FOR NEW GENERATIONS OF LEAD/ACID BATTERIES

Secondary lead will become more and more the main source of raw material for battery producers. The final objective of this study is to define maximum levels of impurities compatible with the use of secondary lead for oxide production for maintenance-free automotive batteries. Today, statistical investigations show that the quality of secondary lead can vary with the smelter, and can be adjusted in certain cases, but it is necessary to evaluate more accurately the effect of each harmful impurity (alone or in combination). Impurities affect principally the self-discharge of batteries. Addition of impurities to the electrolyte has been proved to give non-realistic values of their real influence in batteries. In order to obtain accurate results of the effect of impurities at various levels, syntheses of Barton or mill oxides containing Bi or Ag added to lead of high purity have been undertaken. It has been clearly shown that levels up to 200 ppm Bi or 40 ppm Ag can be admitted without significant differences in the performances of automotive batteries.