A system for determining an operating mode of a battery includes a voltage sensor configured to detect a present voltage across terminals of the battery. The system further includes a non-transitory memory configured to store previously detected voltages across the terminals of the battery, and a previous operating mode of the battery. The system further includes a processor coupled to the voltage sensor and the non-transitory memory and configured to determine the operating mode of the battery by comparing the present voltage across the terminals of the battery to the previously detected voltages of the battery and based on the previous operating mode of the battery.