Patent attributes
For the measurement of the voltage of each block which constitutes a battery pack with different timings, a voltage (V) and current (I) every block the current of which is measured at the same timing as the voltage is measured are read (S100-S108) and an inner resistance (R) is derived from the temperature (T) of the assembled battery (S110, S112). A value of the difference (IN−IN+1) of two currents corresponding to two voltages of respective blocks of a plurality of battery blocks multiplied by the inner resistance (R) of the battery pack is added to the difference (VN−VN+1) of two voltages to calculate the voltage difference ΔV (S116). When the maximum value ΔVmax of the calculated voltage difference ΔV exceeds the threshold value Vref, the state is judged to be an overdischarge (S122, S124, S128).
