Process for detecting remaining capacity of battery

• US 5,658,682 A
• Filed: 02/20/1996
• Issued: 08/19/1997
• Est. Priority Date: 12/11/1992
• Status: Expired due to Fees

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Usuda, Masafumi, Kayano, Morio
• Primary Examiner(s): NUZZOLILLO, MARIA
• Application Number:
  US08/603,542
• Time in Patent Office: 546 Days
• Field of Search: 429/90-94, 324/427, 324/431
• US Class Current: 429/92
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A maximum output power and a discharged electric power amount from the battery is calculated; a future variation in maximum output power relative to the discharged electric power amount is evaluated, thereby determining a remaining capacity of the battery on the basis of the electric power amount discharged until the maximum output power reaches a preset lowest maximum-output power. Thus, the remaining capacity of the battery can be correctly detected, irrespective of the charged state, the discharge rate, the degree of deterioration of the battery and the like.

Claims

1. A process for detecting a remaining capacity of a battery after a period of time of discharging use of the battery, comprising the steps of:

measuring values of discharging current and voltage over the period of time;

determining a discharging current-voltage relationship characteristic of the battery based on a relationship between said measured discharge current and voltage over a range of discharging currents and voltages;

calculating maximum output power densities of the battery based on said determined relationship characteristic over the period of time;

calculating discharged electric power amounts of the battery based on values of said measured discharge current and voltage over the period of time;

determining a relationship between said maximum output power densities and said discharged electric power amounts over the period of time;

determining a maximum discharged electric power amount at a preset lowest maximum output power density based on said determined relationship between maximum output power densities and discharged electric power amounts of the battery;

determining the difference between said determined maximum discharged electric power amount and a present value of said calculated discharged electric power amount;

detecting said determined difference as a present remaining capacity of the battery; and

driving a battery system monitoring means in response to said detected remaining capacity of the battery.

2. A process for detecting the remaining capacity of a battery according to claim 1, wherein the predetermined relationship between the maximum output power density and the discharged electric power amount of the battery is determined by at least a primary regression.

3. A process for detecting the remaining capacity of a battery according to claim 1, wherein the predetermined relationship between the maximum output power density and the discharged electric power amount of the battery is determined by a comparison of an initial value of maximum output power density with an actually measured value of maximum output power density.

4. A process for detecting the remaining capacity of a battery according to claim 1, wherein a battery condition correcting factor is calculated based on predetermined assumed values of maximum output power density and discharged electric power amount in comparison with current said calculated values of maximum output power density and discharged electric power amount.

5. A process for detecting the remaining capacity of a battery according to claim 1, wherein a battery condition correcting factor is calculated based on predetermined assumed values of maximum output power density and discharged electric power mount in comparison with current said calculated values of maximum output power density and discharged electric power amount.

6. A process for detecting the remaining capacity of a battery according to claim 1, wherein the step of calculating said maximum output power density includes a step of dividing by a weight of the battery for producing said maximum output power density density value.

7. A process for detecting the remaining capacity of a battery according to claim 1, wherein the determined relationship characteristic of the battery is a linear relationship between discharge current and voltage approximated from a plurality of measurements of said discharging currents and voltage during a plurality of discharges of the battery.

8. A process for detecting the remaining capacity of a battery according to claim 1, wherein said range is a predetermined range of discharging currents between maximum and minimum discharging currents.

9. A process for detecting the remaining capacity of a battery according to claim 1, wherein said range is a predetermined range of discharging currents from zero to an intermediate discharging current substantially below a maximum discharging current.

10. A process for detecting the remaining capacity of a battery according to claim 1, wherein a correction factor based on said calculated maximum output power densities and discharged electric power amounts during the period of time is used for modifying values of said predetermined relationship for determining the maximum discharged electric power amount.

11. A process for detecting the remaining capacity of a battery according to claim 1, wherein the step of calculating said maximum output power densities includes multiplying one-half of the maximum discharge current at a minimum voltage in said determined relationship characteristic by one-half of the maximum value of the maximum voltage at a minimum discharge current in said determined relationship characteristic.

12. A process for detecting a remaining capacity of a battery after a period of time of discharging use of the battery, comprising the steps of:

measuring values of discharging current and voltage over the period of time;

determining a discharging current-voltage relationship characteristic of the battery based on a relationship between said measured discharge current and voltage over a range of discharging currents and voltages;

calculating maximum output power densities of the battery based on said determined relationship characteristic over the period of time;

calculating discharged electric power amounts of the battery based on values of said measured discharge current and voltage over the period of time;

determining a relationship between said maximum output power densities and discharged electric power amounts over the period of time;

determining a maximum discharged electric power amount at a lowest effective a maximum output power density based on said determined relationship between maximum output power densities and discharged electric power amounts of the battery;

determining the difference between said determined maximum discharged electric power amount and a present discharged electric power amount and detecting said determined difference as the remaining capacity of the battery; and

driving an indicator to indicate said determined difference as a present remaining capacity of the battery.

13. A process for detecting the remaining capacity of a battery according to claim 12, wherein the determined relationship between the maximum output power density and the discharged electric power of the battery is determined by at least a primary regression.

14. A process for detecting the remaining capacity of a battery according to claim 12, wherein the determined relationship between the maximum output power density and the discharged electric power of the battery is determined by a comparison of an initial value of maximum output power density with an actually measured value of maximum output power density.

15. A process for detecting the remaining capacity of a battery according to claim 12, wherein a battery condition correcting factor is calculated based on predetermined assumed values of maximum output power density and discharged electric power in comparison with current said calculated values of maximum output power density and discharged electric power.

16. A process for detecting the remaining capacity of a battery according to claim 12, wherein a battery condition correcting factor is calculated based on predetermined assumed values of maximum output power density and discharged electric power amount in comparison with current said calculated values of maximum output power density and discharged electric power amount.

17. A process for detecting a remaining capacity of a battery after a period of time of discharging use of the battery, comprising the steps of:

measuring values of discharging current and voltage over the period of time;

determining a discharging current-voltage relationship characteristic of the battery based on a relationship between said measured discharge current and voltage over a range of discharging currents and voltages;

calculating maximum output power values of the battery based on said determined relationship characteristic over the period of time;

calculating discharged electric power amounts of the battery based on values of said measured discharge current and voltage over the period of time;

determining a relationship between said maximum output power values and said discharged electric power amounts over the period of time;

determining a maximum discharged electric power amount at a preset lowest maximum output power density based on said determined relationship between maximum output power values and discharged electric power amounts of the battery;

determining the difference between said determined maximum discharged electric power amount and a present value of said calculated discharged electric power amount; and

detecting said determined difference as a present remaining capacity of the battery after the period of time; and

driving a remaining-capacity indicator in response to said determined difference for indicating a present remaining capacity of the battery on said remaining-capacity indicator.