Vehicle battery monitor apparatus and method for detecting battery change
A battery monitor apparatus and method for an automotive battery system including a battery for supplying power to in-vehicle electrical equipment and sensors for detecting battery voltage, the charge/discharge current and the battery temperature are disclosed. The capacitance and the internal actual resistance of the battery are calculated at the time of starting the engine. Further, the theoretical internal resistance of the battery corresponding to the ambient temperature and the battery open-circuit voltage during the stationary engine state are detected in advance. Based on the change in the battery open-circuit voltage, the battery change is provisionally determined. After that, battery change or degeneration can be determined based on battery capacitance, the actual and theoretical internal resistance values of the battery, the battery open-circuit voltage and the provisional battery change determination value.
1. An automotive battery monitor apparatus comprising:
a battery change detector for detecting that the battery mounted on a vehicle has been changed;
a battery real internal resistance calculation unit for detecting, upon receipt of an engine start request and upon detection by the battery change detector that the battery has been changed, the internal resistance of the battery based on the battery discharge state at the time of starting the engine;
a battery capacitance calculation unit for calculating the battery capacitance after the battery change based on the internal resistance calculated by the battery real internal resistance calculation unit;
a battery charge rate calculation method changing unit for changing the method of calculating the battery charge rate based on the battery capacitance calculated by the battery capacitance calculation unit; and
a battery degeneration detector for detecting the degeneration of the battery based on the calculated battery capacitance when the battery change detector determines that the battery has not been changed;
wherein the battery real internal resistance calculation unit detects the real internal resistance of the battery by dividing a change of the battery voltage at predetermined time intervals by a change of the battery current at the same predetermined time intervals, the detection occurring after a battery change at the time the engine is started but before the vehicle is driven.