Patent ID: 7990111
Filing Date: 2011-08-02
Classification: B60L,G01R,Y02T

Abstract:
1. An apparatus that estimates an internal electric state of an in-vehicle secondary battery of which terminal voltage is regulated at a target value by operating an in-vehicle alternator, the apparatus comprising: a current detector that detects charge current flowing to the battery and discharge current from the battery; sampling means that samples and holds, at intervals, the current detected by the current detector; charge means that performs constant-voltage charging of the battery at a preset value given to the battery immediately after start of the vehicle or during running of the vehicle; first calculation means that calculates a polarization-relevant quantity relevant to an amount of polarization caused in the battery immediately after start of the constant-voltage charge using data of the charge current from the sampling and holding means; determination means that determines whether or not a change rate of the calculated polarization-relevant quantity is less than a given threshold; acquisition means that acquires from the sampling and holding means a plurality of data of the charge current sampled and held during a predetermined period of time when it is determined that the change rate of the calculated polarization-relevant quantity is less than the given threshold; second calculation means that calculates a value of the charge current to be accumulated until the charge current reaches a given final value, using the plurality of data of the charge current; and estimation means that estimates the internal electric state of the battery based on the calculated accumulated value of the charge current.