Eight years of experience with valve-regulated batteries for automotive use

In 1985, Matsushita developed a valve-regulated lead/acid (VRLA) battery with an expanded grid for automotive use. Since 1989, these batteries have been adopted as original equipment for cars. To take full advantage of their benefits, the batteries are installed away from the engine compartment, for example, in the boot of the car. Despite a steady market for automotive VRLA batteries, there are still a few problems that accompany their use. These must be solved in order to enhance reliability and improve customer satisfaction. The major areas of concern are life at high temperature, and recovery after over-discharge and long standing. Work in these areas is reported here.