Understanding VRLA charging and other operational characteristics

Recommended float voltages for many valve-regulated Pb-acid (VRLA) battery designs are based on commonly-held assumptions regarding minimum plate polarization. Long term testing has shown that some of these standard voltages may be unnecessarily high. However, optimizing VRLA operation in a laboratory environment is not sufficient if charging behavior changes markedly under other operating conditions. The authors have undertaken an extensive program to verify the battery behavior, using the Tafel relationship and accelerated life testing. This paper explores the way in which charging and other characteristics vary, particularly at elevated temperatures. The test results shed new light on the accuracy of high-temperature accelerated life testing as it is often carried out on VRLA cells. >