Lead-acid battery life prediction device

摘要

PURPOSE:To estimate the life of a battery with high accuracy by short-circuiting a charging current measuring means during the period of time for recovery charging when the life of the lead-acid battery is estimated based on the accumulated value of over-charged quantity of electricity. CONSTITUTION:The switch control section 5B of a recovery charging detection circuit 5 is controlled by the measured voltage of a voltage measuring instrument 5A wherein a switch 13 is closed when the voltage of a battery 3 is less than the first set value, and the switch 13 is opened after a definite time has elapsed when it is equal to or more than the second set value. At the later stage of discharging and at the starting time of charging, the switch 13 is closed so that the measurement of recovery charging current by a shunt 10 is interrupted. Discharging current from the battery 3 flows through a diode 12 or the closed switch 13. Recovery charging is progressed so that the switch 13 is opened, and floating charging current after recovery charging has been effected flows through the shunt 10 so as to be measured. The accumulated value of stored self-discharging is subtracted from the accumulated value of the current one so that the over charged quantity of electricity is thereby obtained.