Abstract: The performance and life of electric-vehicle battery-systems are affected by the temperature. A
liquid cooling/heating Battery Thermal Management (BTM) with an optimum geometric structure was designed
to keep the average battery-system temperature in the range from 20 ℃ to 45 ℃ and the temperature gradient
within 3 ℃ . According to overall system flow balancing in a BTM, cooling/heating plates with different structure
parameters were simulated to investigate cooling effects of the BTM. An infrared thermal imager monitored the
cooling/heating plate temperature rises in battery-system heating experiments. Experimental and simulation
results were shown to be the same. The results show that the structure with an inlet and an outlet on the
same side has an even flow distribution. By combining the simulation and optimization, the obtained optimum
combination of the inlet velocity and the temperature in the cooling/heating plate reduces the plate-surfacetemperature
standard-deviation to 2.61 ℃ , and makes the battery system uniformly heated.

Key words: electric vehicle (EV), battery thermal management (BTM), battery module, flow balancing, liquid
cooling/heating plate, combined simulation and optimization