Battery charge level detecting device

摘要

In the area of the charge level of 20 ~ 80% where the charge level of a battery (50) does not appear in the terminal voltage of the battery, the battery ECU (68) estimates charge level by integrating the currents of the charge and discharge of the battery. When the engine ECU (46) detects that the ignition key is turned on, the motor generators (26, 28) are driven by the engine (10), and the generated electric power is accumulated in the battery (50). When the area where the charge level appears in the terminal voltage, is reached, the calculation of the charge level is performed from the current and voltage at that time. When this charge level has reached 80%, the calibration of said estimated charge level is performed by this value. Furthermore, it is also possible for this calibration to be prohibited when a heavy current is flowing and the error may become large in the calculation of the charge level. By the above mentioned methods, the charge level of a battery can accurately be detected.