Valve-regulated lead/acid batteries for electric vehicles: Present and future

In the USA, the State of California has officially planned to introduce zero-emission vehicles (ZEVs) in 1998. In Japan, Hino Motors, Ltd., has developed the HIMR bus as a low-pollution vehicle. Worldwide, vehicle developers are using valve-regulated lead/acid (VRLA) batteries as the power sources. This is because the technology has easy maintenance and good safety characteristics. The authors' company is working on the development of VRLA batteries and is continuing to improve them via feedback from both bench and field tests. By means of better positive plates, negative plates and separators, longer battery life has been achieved. This paper discusses the present status and future advancement of the VRLA batteries.