What is thermal runaway?
Batteries in enclosures can go into thermal runaway, which very rapidly produces hydrogen, whenever several conditions are simultaneously present. 1) The batteries are exposed to high temperatures inside the enclosure (above 100 F) for a sustained period, either because the enclosure is unprotected, or because the cooling system is inadequate or has failed. 2) The batteries continue to be charged at high voltage and current because there is no temperature compensation in the battery charging circuit, or because said circuit has failed. 3) Batteries have aged and become dehydrated. Solar heating will cause the internal temperature of a plain metal battery box to go above 100 F in most of the country during much of the year. According to Bellcore, internal enclosure temperatures will increase to between 21 F and 27 F above the external daily high temperature, depending on the U. S. location. Thus, if the external daily high temperature reaches only 80 F, then the internal temperature of
