Method of detecting battery internal resistance

The method of detecting battery internal resistance detects battery 1 temperature and internal resistance, and computes internal resistance at each temperature. In addition to detecting battery 1 temperature, the method detects battery 1 voltage and current at each detected temperature and computes internal resistance from the measured voltages and currents. Further, internal resistance computed from actual measurements establishes battery internal resistance versus measured temperature to determine internal resistance at a plurality of battery 1 temperatures.