Method for charging determining life of and detecting state of charge of battery

• US 6,583,606 B2
• Filed: 05/29/2001
• Issued: 06/24/2003
• Est. Priority Date: 05/29/2000
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Takami, Nobuyuki, Yoshihara, Yasuyuki, Jimbo, Hiroyuki, Koike, Kiichi
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US09/867,279
• Publication Number:
  US 20020014879A1
• Time in Patent Office: 756 Days
• Field of Search: 320/132, 320/137, 320/149, 324/426, 324/431, 324/433, 340/635, 340/636, 429/61, 429/90
• US Class Current: 320/149
• CPC Class Codes: H02J 7/0069 Charging or discharging for charge maintenance, battery initiation or rejuvenation

Abstract

A method for charging a lead battery is provided. In the method, a SOC is controlled so as to be less than 100%, and when the lead battery has not been charged and discharged for a predetermined time, refresh charge is performed so that the SOC becomes at least 90% or more.

Claims

1. A method for charging a lead battery, wherein:

a state of charge is controlled so as to be less than 100%; and

when the lead battery has not been charged and discharged for a predetermined time, refresh charge is performed so that the state of charge becomes at least 90% or more.

5. A method according to claim 1, wherein:

in the refresh charge, after a charging current is lowered to a predetermined value even though the lead battery is subjected in constant-voltage charge using a predetermined control voltage, constant-current charge is performed, or constant-voltage charge is performed using a control voltage higher than the predetermined control voltage.

7. A method according to claim 1, wherein the state of charge is calculated based on an open circuit voltage of the lead battery immediately before the start of charge and discharge of the lead battery.

8. A method according to claim 1, wherein the state of charge is calculated based on an open circuit voltage of the lead battery when charge and discharge are paused, or based on a discharging current and a discharging voltage.

2. A method for charging a lead battery, wherein:

a state of charges is controlled so as to be less than 100%; and

every time the lead battery is charged and discharged in predetermined time intervals, refresh charge is performed so that the state of charge becomes at least 90% or more.

6. A method according to claim 2, wherein a set value of the state of charge, after the refresh charge, is increased with an increase in a cycle of the refresh charge.

3. A method for charging a lead battery, wherein:

a state of charge is controlled so as to be less than 100%; and

when the state of charge is lowered below a predetermined value, refresh charge is performed so that the state of charge becomes at least 90% or more.

4. A method for charging a lead battery, wherein:

a state of charge is controlled so as to be less than 100%; and

when a temperature of the lead battery is less than or equal to a predetermined value, refresh charge is preformed so that the state of charge becomes at least 90% or more.

9. A method for determining the life of a battery, wherein:

the battery is subjected to refresh charge, a state of charge of the battery after the refresh charge is presumed to be 100%, charge and discharge are performed, and

a state of charge (1) of the battery after the charge and discharge, the state of charge (1) obtained base on quantity of the charge, and a state of charge (2) obtained based an open circuit voltage are compared with each other, and the life of the battery is determined based on a difference between the state of charge (1) and the state of charge (2).

10. A method for determining the life of a battery, wherein a first DC-IR value is obtained with respect to a state of charge of the battery in an initial state where the battery is not degraded, based on charging and discharging currents and an open circuit voltage, and

the first DC-IR value is compared with a second DC-IR value of the battery in the initial state obtained in advance, and the life of the battery is determined based on a difference between the first and second DC-IR values.

11. A method for detecting a state of charge or a lead battery, wherein an open circuit voltage of the lead battery or a discharging voltage of the lead battery when a discharging current is less than or equal to a predetermined value is measured, and the state of charge of the lead battery is detected based on a relationship between the predetermined open circuit voltage and the state of charge or a relationship between the discharging voltage and the state of charge, and

when the state of charge is calculated, a variation in the open circuit voltage or a variation in the discharging voltage and a variation in the state of charge are measured with respect to a predetermined time, and the relationship between the predetermined open circuit voltage and the state of charge or the relationship between the discharging voltage and the state of charge is corrected.

12. A method according to claim 11, wherein the variation in the state of charge is obtained based on a quantity of charged and discharged electricity obtained by integrating charging and discharging currents in the predetermined time.

13. A method for determining degradation of a lead battery using a method for detecting a state of charge of a lead battery according to claim 11 or 12, wherein the degradation of the lead battery is determined based on a corrected relationship between an open circuit voltage of the lead battery and the state of charge or a corrected relationship between a discharging voltage and the state of charge.

14. A method according to claim 13, wherein a ratio of a variation on the open circuit voltage or a variation in the discharging voltage to a variation in the state of charge is calculated, and the degradation of the lead battery is determined based on the ratio.

15. A method according to claim 14, wherein a value (K) is calculated by dividing the variation in the open circuit voltage or the variation in the discharging voltage by the variation in the state of discharge, and when the value (K) is greater than or equal to a predetermined value, it is determined that the lead battery is degraded.