Experiments on thermal run-a-way and its management for electrolyte immobilized lead-acid batteries

The thermal characteristics of the AT&T VR electrolyte immobilized (EI) lead-acid battery have been evaluated from ambient temperatures to 158°F and float voltages to 2.5 V/cell. The intent of this experimental program was to determine and evaluate the battery´s thermal behavior in applications and configurations in which it is presently used. The test program included free-standing cells and a 48 V 375 Ah battery in a close packed cubical configuration. It was concluded that free-standing cells and cells closely packed in a cube configuration will not exhibit thermal runaway when floated at 2.27 V/cell and temperatures at or below 131°F. The 48 V 375 Ah battery at 77°F and potentials above 2.5 V/cell exhibits the symptoms of thermal runaway. When elevated temperature and voltage conditions are encountered it is recommended that the battery float voltage be temperature compensated. The recommended coefficient to temperature compensate float voltage is -3 mV/°C. The derivation of this coefficient is given