Factors that accelerate the wetting of auxiliary electrodes in sealed lead/acid batteries

An auxiliary electrode is a useful means to operate successfully a sealed lead/acid battery for a long cycle life by absorbing any excessive amounts of gas. When the auxiliary electrode becomes wet with electrolyte, its capability for gas absorption deteriorates and, as a result, the service life of the battery is shortened. Consequently, it is very important to identify the main factors that accelerate the wetting of auxiliary electrodes. An auxiliary electrode in a sealed lead/acid battery is partly immersed in electrolyte and partly exposed to a mixed-gas atmosphere. The gas pressure in the battery can change over a wide range with time. The potential of the auxiliary electrode is regulated to a specific value through the use of a non-linear type resistor. Both electrochemical and chemical reactions occur simultaneously on the auxiliary electrode. In this study, various factors that accelerate the wetting of auxiliary electrodes have been identified and the degree of their individual effects have been determined. As a result, it has been found that the electrochemical reaction exerts the strongest effect.