Further demonstration of improved performance from lead-acid batteries manufactured with bismuth-bearing high-purity lead

This investigation examines the cycle-life of valve-regulated lead-acid (VR LA) batteries which have been fabricated either with the manufacturer's own leady oxide (termed 'factory oxide') or with leady oxide prepared from Pas minco VRLA Refined(TM) lead (termed 'VRLA Refined(TM) oxide'). VRLA Refined (TM) lead is a soft lead of high purity with a specified amount (0.05 wt.%) of bismuth. To provide a comparison of performance, benchmark tests are pe rformed on batteries of equivalent design that have been supplied by two di fferent manufacturers. Batteries made from factory oxide exhibit cycle-live s which exceed the minimum life specified by the Japanese Industrial Standa rd (JIS) test and by the International Electrotechnical Commission (IEC) te st. Under the JIS procedure, the failure of both types of battery is due to expansion of the positive-plate material and subsequent extensive loss in connectivity between the constituent agglomerates of lead dioxide. By contr ast, battery failure under the IEC procedure is caused by undercharging of the negative plates. The use of VRLA Refined(TM) oxide produces a marked im provement in battery cycle-life. Gains in performance from 675 to 800 cycle s and from 510 to 675 cycles are obtained under JIS and IEC tests, respecti vely. It appears that the presence of bismuth at the specified level extend s battery life by strengthening and increasing the connectivity in the posi tive-plate material (JIS test) or by raising the chargeability of negative plates (IEC test). (C) 2000 Elsevier Science S.A. All rights reserved.