Thermal behavior analysis of nickel/metal hydride battery during overcharging

To analyze the thermal behavior of the cylinder Ni/MH battery during overcharging[ff0c]a two-dimensional thermal model is provided in this work. More reliable data is provided to create the precise thermal model. The amount of heat of the battery during overcharging at different currents was measured using quartz frequency microcalorimeter. To obtain the heat transfer coefficient of the battery during overcharging, the heat dissipation rate was fitted into linear functions and three different exponential functions from the temperature value measured by the microcalorimeter. The heat dissipation process after the linear stage was regared to accord with some mathematical differential expressions, which facilities understanding of the variation rule of heat dissipation rate during the transition stage and overcharging process. Theoretical values were used as heat generation rates in the heat transport equation. Using the measured data, the internal temperature profiles at the end of each stage during charging at 1C, 3C and 5C were simulated using FEM.