Review of factors that affect the deep cycling performance of valve-regulated lead/acid batteries

The effects of compression, positive-grid growth, electrolyte stratification and uniformity across a series string of cells during deep-cycling service of valve-regulated lead/acid batteries are considered. Without adequate control, each of these will cause premature failure. Although substantial improvements in cycleability have been made in recent years, more understanding and optimization of these factors is necessary for further improvements. In particular, little is known about the changes in the properties of separators during service that effect compressive forces on the positive plate, and more knowledge is required on the influence of grid growth and on the influence of cell design on electrolyte stratification in valve-regulated batteries. In addition, the paper considers the progressive variation between cells in long series strings, which is a major cause of early failure of these designs.