Battery charging rate estimation device and battery charging rate estimation method

摘要

Battery state-of-charge estimation apparatus detects current-passage state of charging/discharging current through a secondary battery just before passage of current stops, measures voltage value between both electrodes of the secondary battery after passage of charging/discharging current stops, measures elapsed time from when passage of charging/discharging current stops to when voltage value between both electrodes of the secondary battery is measured, estimates open-circuit voltage value using the detected current-passage state, the measured voltage value, the measured elapsed time, and open-circuit voltage value relationship information which relates to relationship between transition of voltage value between both electrodes of the secondary battery after passage of current stops and the open-circuit voltage value of the secondary battery and which is prepared for each current-passage state just before passage of charging/discharging current stops and previously stored in ROM of control unit. State of charge of the battery is estimated based on the estimated open-circuit voltage value.