Method of detecting residual capacity of secondary battery

• US 6,920,404 B2
• Filed: 09/20/2001
• Issued: 07/19/2005
• Est. Priority Date: 09/28/2000
• Status: Expired due to Fees

• Current Assignee: GS Yuasa International Ltd. (GS Yuasa Corporation)
• Original Assignee: Japan Storage Battery Company Limited (GS Yuasa Corporation)
• Inventors: Yamanaka, Kenji
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Desta, Elias
• Application Number:
  US10/148,234
• Publication Number:
  US 20020193954A1
• Time in Patent Office: 1,398 Days
• Field of Search: 702 60- 65, 702/70, 702/124, 702/126, 702180-184, 702/57, 702/187, 702/189, 702/198, 702FOR 103-106, 702/111, 702/134, 702/170, 702/171, 320/127, 320/134, 320149-159, 324426-437, 324/439, 324/441, 324600-601, 324/649, 324/691, 324/720, 324/721, 700/293, 700/297, 700/298, 307/116, 307/125, 307/130, 307/131, 307/132.EA
• US Class Current: 702/63
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables

Abstract

Correlations between a residual capacity of a secondary battery and 4 parameters of an internal resistance, temperature, a discharge current and one of an open circuit voltage and a discharge voltage of the secondary battery are previously determined and a contour map of the residual capacity and 2 of the parameters is made, for example. Then, at least 2 varying parameters selected from the 4 parameters are detected while the secondary battery is in use and collated with the correlations to estimate the residual capacity of the secondary battery.

Claims

1. A method for estimating a residual capacity of a secondary battery, said method comprising:

assigning parameters of an internal resistance, a temperature, a discharge current and one of an open circuit voltage and a discharge voltage of the secondary battery;

collating the parameters with previously determined correlations between the parameters and the residual capacity of the secondary battery; and

determining the correlations of the secondary battery having a specific history, said determining of the correlations comprising;

plotting a measured internal resistance and one of the open circuit voltage and the discharge voltage into a voltage-resistance figure;

measuring discharge capacities corresponding to each plot at a temperature and a discharge current; and

drawing lines between plots in the voltage-resistance figure such that plots having the same discharge capacity are connected.

4. The method according to claim 1, further comprising detecting at least two varying parameters selected from the parameters while the secondary battery is in use.

5. The method according to claim 1, wherein the internal resistance plotted into the voltage-resistance figure is expressed as an internal resistance ratio on the basis of an initial internal resistance value define to be 1.0.

8. The method according to claim 1, wherein the internal resistance is assigned by an AC four-terminal method or a discharge I-V method.

11. The method according to claim 4, wherein the internal resistance is assigned by an AC four-terminal method or a discharge I-V method.

12. The method according to claim 5, wherein the internal resistance is assigned by an AC four-terminal method or a discharge I-V method.

2. A method for estimating a residual capacity of a secondary battery said method comprising:

assigning parameters of an internal resistance a temperature, a discharge current and one of an open circuit voltage and a discharge voltage of the secondary battery;

collating the parameters with previously determined correlations between the parameters and the residual capacity of the secondary battery; and

detecting at least two varying parameters selected from the parameters while the secondary battery is in use.

6. The method according to claim 2, wherein the at least two varying parameters are the internal resistance and one of the open circuit voltage and the discharge voltage of the secondary battery.

9. The method according to claim 2, wherein the internal resistance is assigned by an AC four-terminal method or a discharge I-V method.

3. A method for estimating a residual capacity of a secondary battery, said method comprising:

detecting parameters of an open circuit voltage or a discharge voltage and an internal resistance while the secondary battery is in use;

collating the detected parameters with previously determined correlations between an open circuit voltage or a discharge voltage and an internal resistance and a residual capacity under a temperature and a discharge current to calculate the residual capacity under the temperature and the discharge current; and

multiplying the residual capacity under the temperature and the discharge current by a temperature coefficient and a discharge current coefficient corresponding to the temperature and the discharge current of a condition under which the secondary battery is in use to calculate the residual capacity of the secondary battery under the condition.

10. The method according to claim 3, wherein the internal resistance is assigned by an AC four-terminal method or a discharge I-V method.

7. A method for estimating a residual capacity of a secondary battery, said method comprising:

assigning parameters of an internal resistance, a temperature, a discharge current and one of an open circuit voltage and a discharge voltage of the secondary battery; and

collating the parameters with previously determined correlations between the parameters and the residual capacity of the secondary battery,

wherein the internal resistance is assigned by an AC four-terminal method or a discharge I-V method.