Edward N. Mrotek

THERMAL MANAGEMENT OF LEAD-ACID BATTERIES FOR ELECTRIC VEHICLES

A Globe Battery Division EV-3000 electric vehicle battery with its in-cell electrolyte circulation pumps was instrumented with temperature sensors and subjected to singular and repetitive deep discharge cycles while being cooled by natural and forced air convection. Temperature excursions within the battery became severe with repetitive cycling and natural convection cooling. The EV-3000s in-cell electrolyte pumps were shown to be a definite aid to battery thermo-regulation by i) allowing the charging process to be more energy efficient and thus generating less total heat, ii) reducing peak cell temperature, iii) producing a more uniform temperature distribution within the cells, and iv) transporting the elevated temperature, dense electrolyte produced during charge from the cell stack area to a more active heat transfer surface. Experiments have shown that forced air convection on the external surfaces of the battery can provide effective cooling when the battery is operated under moderate duty cycles and ambient temperatures. It is anticipated, however, that high energy density batteries may require more elaborate thermal management when subjected to elevated duty cycles or extreme external temperatures.