US 2010/0072949 A1Published application

Charging/Discharging Control Unit for Lithium Secondary Battery

AssigneeHitachi, Ltd.

InventorsYoshiaki Kumashiro, Yoshimi Yanai, Eiji Seki

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Abstract

In a charging/discharging unit provided with: a lithium secondary battery, a voltage detecting sensor for detecting a voltage and a current detecting sensor; the charging/discharging control unit is further provided with a controller, and a discharging element for performing a constant voltage discharging operation of 3 V. A voltage, V0, of the battery when a discharging operation is terminated (t=0) is measured by the voltage detecting sensor. If V0≦3.6 V, within a rest time during which the battery is not charged/discharged until a next charging operation, a voltage, V1, of the battery when a time, t1, has elapsed is measured by the voltage detecting sensor. If this voltage charge is in a range of V1−V0≧0.2 V, then the constant voltage discharging operation of 3 V is carried out for a time duration longer than or equal to 1 hour.

Claims15

Dependent claims

A charging/discharging control unit for a lithium secondary battery comprising:

a lithium secondary battery having a positive electrode and a negative electrode, which are capable of charging/discharging electric charges, and an electrolytic solution containing lithium ions;
a voltage detecting means for detecting a voltage of said lithium secondary battery;
and
a current detecting means for detecting charging/discharging currents of said lithium secondary battery;
wherein:
said charging/discharging control unit of the lithium secondary battery is further comprised of:
a controller for controlling a discharge voltage of said lithium secondary battery;
and
a discharging means for performing a constant voltage discharging operation of said lithium secondary battery;
and wherein:
in a case that a voltage, V0, of said lithium secondary battery when the discharging operation of said lithium secondary battery is terminated becomes V0≦Vcut with respect to a reference voltage, Vcut, if a voltage change, V1-V0, after a time, t1, has elapsed from the termination of the discharging operation is larger than or equal to a predetermined value, AV, then said controller causes said discharging means to perform the constant voltage discharging operation at a voltage, Vd, during a rest time until a next charging operation of the lithium secondary battery is commenced.

8 more elements

Dependencies are inferred from the claim text.