Thermal analysis of rapid charging nickel/metal hydride batteries

A two-dimensional thermal model was presented to predict the temperature distribution of cylindrical 8-Ah Ni/MH battery. Under the forced convection, the temperature rise of the battery is up to about 37, 42 and 51 °C, and the temperature profiles become non-uniformed at the end of 1C, 2C and 4C rate charge, respectively. It is indicated that the increase of the convection coefficient can decrease the battery temperature, however, lead seriously to the less uniform temperature profile across the battery. The numerical studies indicate that the increase of thermal conductivity can improve the uniformity of temperature profile to some extends. The battery temperature increases obviously when charged at higher rates. Overcharge can result in an increasingly higher temperature rise and a steeper temperature gradient within a battery.