Abstract: A battery ECU executes a program that includes the steps of: sensing a vehicle speed; sensing a battery temperature; calculating a battery SOC; calculating, based on the battery temperature and battery SOC, a vehicle speed threshold value for starting charge limiting control; and setting a charge limiting flag for limiting an amount of electric energy to be to be charged even before regenerative braking, if the sensed vehicle speed is higher than the calculated vehicle speed threshold value.

Abstract: A battery characteristic detecting method according to the invention includes a first step in which constant current discharge from a battery is performed at a predetermined current value, and a voltage during constant current discharge is measured; a second step in which overpotential for mass transfer control in the battery or resistance for the mass transfer control in the battery is calculated based on the voltage measured in the first step; and a third step in which a determination that a characteristic change has occurred in the battery is made, when the overpotential for the mass transfer control in the battery or the resistance for the mass transfer control in the battery calculated in the second step is larger than a predetermined threshold value.

Abstract: A replacement method is provided for replacing a to-be-replaced battery module with a replacing fresh battery module in a battery assembly formed by electrically connecting a plurality of battery modules in series or parallel. The method includes the step (S110) of charging the fresh battery module so that the quantity of charged electricity of the fresh battery module is 5 to 20% less than the quantity of charged electricity of a battery module other than the to-be-replaced battery module, and the step (S120) of replacing the to-be-replaced battery module with the charged fresh battery module.