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US6756767: Method for charging and discharging battery based on charging capacity

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Filing Information

Inventor(s) Toshimichi Kawai ·
Assignee(s) NEC Corporation ·
Attorney/Agent(s) McGinn & Gibb, PLLC ·
Primary Examiner Edward H. Tso ·
Application Number US10274866
Filing date 10/22/2002
Issue date 06/29/2004
Prior Publication Data
Predicted expiration date 10/22/2022
U.S. Classifications 320/125  · 320/130  ·
International Classifications --
Kind CodeB2
International Classifications 320124 · 320125 · 320130 · 320135 · 320150 · 320160 ·
Foreign Priority JP2001324664 - 10/23/2001 ·
21 Claims, 9 Drawings


Abstract

A nonaqueous-electrolyte secondary battery charging/discharging method that provides a prolonged cyclic life. In the charging/discharging method, a secondary battery is continuously charged unconditionally until a charging capacity exceeds 20% of a full charging capacity. The charging is completed when the charging capacity exceeds 70% of a full charging capacity. A maintenance charging/discharging operation is performed to avoid the full charging capacity being in an error state when dV/dt exceeds a specified value “a” before a charging current exceeds 70% of the full charging capacity. Likewise, the maintenance charging/discharging operation is performed to avoid the full charging capacity being in an error state when dT/dt exceeds a specified value “b” before a charging current exceeds 70% of the charging capacity.

Independent Claims | See all claims (21)

  1. 1. An apparatus for charging and discharging a nonaqueous electrolyte secondary battery, said apparatus comprising: a first switch for connecting or disconnecting a secondary battery and a charging power source; a second switch for connecting or disconnecting the secondary battery and a load; a full charging capacity memory for storing a full charging capacity value of the secondary battery; means for detecting a charging capacity of the secondary battery during charging, for connecting the secondary battery and the charging power source by controlling said first switch when the detected charging capacity is less than a first predetermined ratio of the full charging capacity, and for disconnecting the secondary battery and the charging power source by controlling said first switch when the detected charging capacity is a second predetermined ratio or more of the full charging capacity; means for calculating a voltage variation dV/dt of the secondary battery during charging; means for calculating a temperature variation dT/dt of the secondary battery during charging; means for determining whether or not the voltage variation dV/dt exceeds a first specified value, determining whether or not the temperature variation dT/dt exceeds a second specified value, detecting whether or not the secondary battery is in a full charging state during charging based on the voltage and the temperature of the secondary battery during charging when at least one of the voltage variation dV/dt and the temperature variation dT/dt exceeds the associated specified value, and controlling said second switch when the secondary battery is in a full charging state, thus connecting the secondary battery and the load to permit discharging of the secondary battery; and means for detecting completion of discharging of the secondary battery, computing a full charging capacity based on a discharging current when discharging is completed, and updating the full charging capacity value stored in said full charging capacity memory.
  2. 3. A method for charging and discharging a nonaqueous electrolyte secondary battery, comprising: calculating a voltage variation dV/dt of said secondary battery during charging; calculating a temperature variation dT/dt of said secondary battery during charging; detecting a charging capacity of said secondary battery during charging and then, when the detected charging capacity is less than a first predetermined ratio of a stored full charging capacity, determining whether or not a detected voltage variation dV/dt exceeds a first previously specified value and determining whether or not a detected temperature variation dT/dt exceeds a second previously specified value; when at least one of said detected voltage variation dV/dt and said detected temperature variation dT/dt exceeds the associated previously specified value, detecting whether or not said secondary battery during charging is in a full charging state based on the voltage and the temperature of said secondary battery during charging; discharging said secondary battery when a full charging state is detected; detecting completion of discharging of said secondary battery; computing, upon completion of discharging, a full charging capacity based on a discharging current of said secondary battery, and updating said stored full charging capacity; and completing charging of said secondary battery when said stored charging capacity is a predetermined ratio or more of a stored full charging capacity.
  3. 5. A method for charging and discharging a nonaqueous electrolyte secondary battery, comprising: re-charging a battery, which is discharged, to less than a full charging amount of said battery; performing a maintenance charging/discharging operation to avoid the possibility of an erroneous full charging capacity when dV/dt exceeds a specific value “a” before said charging capacity exceeds 70% of said full charging capacity; and supplying a re-charging amount to a load.
  4. 9. A method for charging and discharging a nonaqueous electrolyte secondary battery, comprising: continuously charging said secondary battery unconditionally until a charging capacity exceeds 20% of a full charging capacity to avoid the temperature and the voltage of said battery becoming unstable in initial charging; ending the charging operation when said charging capacity exceeds 70% of said full charging capacity; performing a maintenance charging/discharging operation to avoid the possibility of an erroneous full charging capacity when dV/dt exceeds a specific value “a” before said charging capacity exceeds 70% of said full charging capacity; and performing a maintenance charging/discharging operation to avoid the possibility of an erroneous full charging capacity when dT/dt exceeds a specific value “b” before said charging capacity exceeds 70% of said full charging capacity.
  5. 12. A method for charging and discharging a nonaqueous electrolyte secondary battery, comprising: re-charging a battery, which is discharged, to less than a full charging amount of said battery; performing a maintenance charging/discharging operation to avoid the possibility of an erroneous full charging capacity when dT/dt exceeds a specific value “b” before said charging capacity exceeds 70% of said full charging capacity; and supplying a re-charging amount to a load.
  6. 13. An apparatus for charging and discharging a battery, said apparatus comprising: a first switch for connecting or disconnecting a battery and a charging power source; a second switch for connecting or disconnecting the battery and a load; a full charging capacity memory for storing a full charging capacity value of the battery; and a controller, wherein: said controller is responsive to the charging capacity of the battery during charging being less than a first predetermined ratio of the full charging capacity, for controlling said first switch to connect the battery and the charging power source, and responsive to the charging capacity of the battery being at least a second predetermined ratio of the full charging capacity for controlling said first switch to disconnect the battery and the charging power source; said controller is further responsive to at least one of the voltage variation dV/dt exceeding a first specified value and the temperature variation dT/dt exceeding a second associated specified value for detecting whether or not the battery is in a full charging state during charging based on the voltage and the temperature of the battery; said controller is further responsive to the battery being in a full charging state for controlling said second switch to connect the battery and the load; and said controller is further responsive to discharging of the battery being completed for computing a full charging capacity based on a discharging current.
  7. 15. A method for charging and discharging a battery, said method comprising: calculating a voltage variation dV/dt of said battery during charging; calculating a temperature variation dT/dt of said battery during charging; when said battery is completely discharged, computing a full charging capacity based on a discharging current of said battery detecting a charging capacity of said battery; when the detected charging capacity is less than a first predetermined ratio of the full charging capacity, charging the battery, determining whether or not a detected voltage variation dV/dt exceeds a first previously specified value, and determining whether or not a detected temperature variation dT/dt exceeds a second previously specified value; when at least one of said detected voltage variation dV/dt and said detected temperature variation dT/dt exceeds the associated previously specified value, detecting whether or not said battery is fully charged based on the voltage and the temperature of said battery.
  8. 17. A method for charging and discharging a battery, comprising: re-charging a battery, which is discharged, to less than a full charging amount of said battery; performing a maintenance charging/discharging operation when dV/dt exceeds a specific value “a” before said charging capacity exceeds 70% of said full charging capacity; and supplying a re-charging amount to a load.
  9. 19. A method for charging and discharging a battery, comprising: charging said battery until a charging capacity exceeds 20% of a full charging capacity; ending the charging operation when said charging capacity exceeds 70% of said full charging capacity; performing a maintenance charging/discharging operation when dV/dt exceeds a specific value “a” before said charging capacity exceeds 70% of said full charging capacity; and performing a maintenance charging/discharging operation when dT/dt exceeds a specific value “b” before said charging capacity exceeds 70% of said full charging capacity.
  10. 21. A method for charging and discharging a battery, comprising: re-charging a battery, which is discharged, to less than a full charging amount of said battery; performing a maintenance charging/discharging operation when dT/dt exceeds a specified value “b” said charging capacity exceeds 70% of said full charging capacity; and supplying a re-charging amount to a load.

References Cited

U.S. Patent Documents

Document NumberAssigneesInventorsIssue/Pub Date
US4829225* Electronic Power Devices, Corp. Podrazhansky et al. May 1989
US5606242* Duracell, Inc. Hull et al. Feb 1997
US6211653* Ford Global Technologies, Inc. Stasko Apr 2001

Foreign Patent Documents

Document NumberAssigneesInventorsIssue/Pub Date
JP9120843May 1997
JP2000023388HITACHI LTDJan 2000
JP2000030750MATSUSHITA ELECTRIC IND CO LTDJan 2000
* cited by examiner

Referenced By

Document NumberAssigneeInventorsIssue/Pub Date
US8604755 --

Patent Family

Document NumberAssigneeInventorsIssue/Pub Date
US20030076074 NEC Corporation Toshimichi Kawai Apr 2003
US6756767 NEC Corporation Toshimichi Kawai Jun 2004