Collaborative investigation on charging electic-vehicle battery systems for night-time load levelling by Japanese electric power companies

摘要

In 1995, ten Japanese electric power companies and CRIEPI started a three-year collaborative investigation of battery systems for electric vehicles (EVs). In the first year, the charging procedure for valve-regulated lead/acid (VRLA) batteries connected in series in EVs has been evaluated for both night-time load levelling and prolonging the cycle life. An EV battery system with VRLA batteries can be charged by both constant current and constant current (CC-CC) and constant current and constant voltage (CC-CV) in less than 8 h under night-time conditions. The charging method with CC-CC prolongs the cycle life further than that with CC-CV. Excess charging capacity on the part of CV in CC-CV charging degrades the positive electrode through softening of the active material.