This study discusses the temperature at the drum brake of a passenger bus vehicle. This is related to the development of electrical energy sources for electric vehicles in general. Heat energy can be converted into electrical energy using thermoelectric generator technology. The purpose of this research is to find the maximum temperature at the drum brake. The limitation in this paper does not show the conversion of heat energy into electrical energy, but displays the potential source of electrical energy from the drum brake's relatively high heat energy. It is estimated that due to the relatively large mass of the bus vehicle with the high moving speed, it will produce a large amount of heat energy. The approach to get the temperature at the brakes is the thermal transient simulation method based on ANSYS Academic. By taking systematic steps, the temperature simulation results were obtained at 259.47 °C. This brake temperature is estimated to be one of the high potential sources of electrical energy for electric buses. Further research is needed for the conversion process of heat energy into electrical energy for large vehicles such as electric buses.