Development of a valve-regulated lead acid battery that decrease float current to prevent thermal runaway

Valve-regulated lead-acid batteries are used to supply power during commercial power failures or rectifier malfunctions. Use of valve-regulated lead-acid batteries, however, often leads to thermal runaway resulting from high ambient temperatures or high float voltage. Thermal runaway then causes destruction of the batteries and resultant service outages. Many attempts have been made to regulate rectifier voltage by varying temperature and controlling float voltage. NTT has developed a new longer-life valve-regulated lead-acid battery whereby float current is decreased, thus preventing thermal runaway