Method and apparatus for operating a battery to avoid damage and maximize use of battery capacity

• US 20070029970A1
• Filed: 01/11/2006
• Published: 02/08/2007
• Est. Priority Date: 08/02/2005
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Qian, Jinrong, Barsukov, Yevgen, Poole, Dan
• Granted Patent: US 7,443,140 B2
• Time in Patent Office: Days
• US Class Current: 320/130
• CPC Class Codes: H01M 10/448 End of discharge regulating measures
• 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: H02J 7/00306 Overdischarge protection
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A method for terminating battery discharge to avoid battery damage and maximize battery usage includes the steps of: (a) determining battery capacity; (b) storing a capacity result of the capacity determining; (c) determining battery voltage; (d) during a monitored battery operation, integrating battery current flow over a time interval to determine an integrated charge value at an end-of-interval-time; (e) determining an extant depth of discharge at the end-of-interval-time; (f) if the extant depth of discharge is neither within a first range of a maximum depth of discharge nor the battery voltage is within a second range of a minimum battery voltage, carrying out steps (d) through (f); (h) if the extant depth of discharge is within the first range of the maximum depth of discharge or if the battery voltage is within the second range of the minimum battery voltage, terminating the monitored battery operation.

Claims

1. A method for operating a battery to terminate discharge of said battery to avoid damage to said battery and substantially maximize use of chemical capacity of said battery;

the method comprising the steps of;

(a) determining a first depth of discharge of said battery while said battery is in a relaxed state before commencement of a first battery operation;

(b) determining current flow from said battery during said first battery operation;

(c) determining a second depth of discharge of said battery while said battery is in a relaxed state after completion of said first battery operation;

(d) determining a battery voltage across said battery;

(e) employing said first depth of discharge, said second depth of discharge and said current flow for determining a maximum chemical capacity of said battery after completion of said first battery operation;

(f) during a next battery operation following said first battery operation, integrating current flow from said battery with respect to time over a time interval to determine an integrated charge value at an end-of-interval-time substantially when said interval ends;

(g) employing said maximum chemical capacity, said integrated charge value and said first depth of discharge to determine an extant depth of discharge at said end-of-interval-time;

(h) if said extant depth of discharge is neither within a first predetermined range of a predefined maximum depth of discharge nor said battery voltage is within a second predetermined range of a predefined minimum voltage, carrying out steps (f) through (g);

(i) if said extant depth of discharge is within a first predetermined range of a predefined maximum depth of discharge or if said battery voltage is within a second predetermined range of a predefined minimum voltage, terminating said next battery operation.

2. A method for operating a battery to terminate discharge of said battery to avoid damage to said battery and substantially maximize use of chemical capacity of said battery as recited in claim 1 wherein said determining at least one of said first depth of discharge and said second depth of discharge is effected by consulting preestablished data relating depth of discharge with at least one measurable parameter associated with operation of said battery.

3. A method for operating a battery to terminate discharge of said battery to avoid damage to said battery and substantially maximize use of chemical capacity of said battery as recited in claim 2 wherein said at least one measurable parameter are said battery voltage and age of said battery.

4. A method for operating a battery to terminate discharge of said battery to avoid damage to said battery and substantially maximize use of chemical capacity of said battery as recited in claim 3 wherein said preestablished data relates depth of discharge for said battery with said battery voltage for a variety of ages of said battery.

5. A method for operating a battery to terminate discharge of said battery to avoid damage to said battery and substantially maximize use of chemical capacity of said battery as recited in claim 4 wherein said preestablished data is embodied in a family of graphic representations relating depth of discharge for said battery with said battery voltage for a variety of ages of said battery.

6. A method for operating a battery to terminate discharge of said battery to avoid damage to said battery and substantially maximize use of chemical capacity of said battery as recited in claim 4 wherein said preestablished data is embodied in a family of data representations relating depth of discharge for said battery with said battery voltage for a variety of ages of said battery.

7. A method for effecting termination of discharge of a battery to avoid damaging said battery and substantially maximize use of capacity of said battery;

the method comprising the steps of;

(a) periodically effecting a determination of capacity of said battery;

said periodic determinations being effected at different ages of said battery;

(b) storing a value representing at least a latest capacity result of said periodic determination of said capacity;

(c) determining a battery voltage drawn from said battery;

(d) during a monitored battery operation, integrating current flow from said battery with respect to time over a time interval to determine an integrated charge value at an end-of-interval-time substantially when said interval ends;

(e) determining an extant depth of discharge at said end-of-interval-time;

(f) in no particular order;

(1) comparing said extant depth of discharge with a predetermined value of maximum depth of discharge; and

(2) comparing said battery voltage with a predetermined value of battery voltage;

(g) if said extant depth of discharge is neither within a first predetermined range of said predetermined value of maximum depth of discharge nor said battery voltage is within a second predetermined range of said predetermined value of battery voltage, carrying out steps (d) through (f);

(h) if said extant depth of discharge is within a first predetermined range of said predetermined value of maximum depth of discharge or if said battery voltage is within a second predetermined range of said predetermined value of battery voltage, terminating said monitored battery operation.

8. A method for effecting termination of discharge of a battery to avoid damaging said battery and substantially maximize use of capacity of said battery as recited in claim 7 wherein step (a), said periodically effecting a determination of capacity of said battery, is carried out by a periodic measuring of said capacity while substantially fully discharging said battery.

9. A method for effecting termination of discharge of a battery to avoid damaging said battery and substantially maximize use of capacity of said battery as recited in claim 7 wherein step (a), said periodically effecting a determination of capacity of said battery, is carried out by the steps of:

(a)(1) determining a first depth of discharge of said battery while said battery is in a relaxed state before commencement of a determining battery operation;

(a)(2) determining current flow from said battery during said determining battery operation;

(a)(3) determining a second depth of discharge of said battery while said battery is in a relaxed state after completion of said determining battery operation; and

(a)(4) employing said first depth of discharge, said second depth of discharge and said current flow for determining a latest capacity result of said capacity of said battery after completion of said determining battery operation.

10. A method for effecting termination of discharge of a battery to avoid damaging said battery and substantially maximize use of capacity of said battery as recited in claim 9 wherein step (g) is modified to:

if said extant depth of discharge is neither within a first predetermined range of said predetermined value of maximum depth of discharge nor said battery voltage is within a second predetermined range of said predetermined value of battery voltage, carrying out steps (d) through (f) for a next monitored battery operation.

11. A method for effecting termination of discharge of a battery to avoid damaging said battery and substantially maximize use of capacity of said battery as recited in claim 10 wherein said determining at least one of said first depth of discharge and said second depth of discharge is effected by consulting preestablished data relating depth of discharge with at least one measurable parameter associated with operation of said battery.

12. A method for effecting termination of discharge of a battery to avoid damaging said battery and substantially maximize use of capacity of said battery as recited in claim 11 wherein said at least one measurable parameter are said battery voltage and age of said battery.

13. A method for effecting termination of discharge of a battery to avoid damaging said battery and substantially maximize use of capacity of said battery as recited in claim 12 wherein said preestablished data relates depth of discharge for said battery with said battery voltage for a variety of ages of said battery.

14. A method for effecting termination of discharge of a battery to avoid damaging said battery and substantially maximize use of capacity of said battery as recited in claim 13 wherein said preestablished data is embodied in a family of graphic representations relating depth of discharge for said battery with said battery voltage for a variety of ages of said battery.

15. A method for effecting termination of discharge of a battery to avoid damaging said battery and substantially maximize use of capacity of said battery as recited in claim 13 wherein said preestablished data is embodied in a family of data representations relating depth of discharge for said battery with said battery voltage for a variety of ages of said battery.

16. An apparatus for controlling operation of a battery to terminate discharge of said battery to avoid damage to said battery and substantially maximize use of chemical capacity of said battery;

the apparatus comprising;

(a) a processing and control unit coupled with said battery;

said processing and control unit determining a first depth of discharge of said battery while said battery is in a relaxed state before commencement of a first battery operation;

said processing and control unit determining a second depth of discharge of said battery while said battery is in a relaxed state after completion of said first battery operation;

(b) a first measuring unit coupled with said battery and with said processing and control unit;

said first measuring unit determining current flow from said battery during said first battery operation;

(c) a second measuring unit coupled with said battery and with said processing and control unit;

said second measuring unit determining a battery voltage across said battery;

said processing and control unit employing said first depth of discharge, said second depth of discharge and said current flow for determining maximum chemical capacity of said battery after completion of said first battery operation;

during a next battery operation following said first battery operation, said processing and control unit integrating current flow from said battery with respect to time over a time interval to determine an integrated charge value at an end-of-interval-time substantially when said interval ends;

said processing and control unit employing said maximum chemical capacity, said integrated charge value and said first depth of discharge to determine an extant depth of discharge at said end-of-interval-time;

if said extant depth of discharge is neither within a first predetermined range of a predefined maximum depth of discharge nor said battery voltage is within a second predetermined range of a predefined minimum voltage, said processing and control unit cooperates with said first and second measuring units to determine a subsequent depth of discharge at a subsequent time;

if said extant depth of discharge is within a first predetermined range of a predefined maximum depth of discharge or if said battery voltage is within a second predetermined range of a predefined minimum voltage, terminating said next battery operation.

17. An apparatus for controlling operation of a battery to terminate discharge of said battery to avoid damage to said battery and substantially maximize use of chemical capacity of said battery as recited in claim 16 wherein said processing and control unit effects said determining at least one of said first depth of discharge and said second depth of discharge by consulting preestablished data relating depth of discharge with at least one measurable parameter associated with operation of said battery.

18. An apparatus for controlling operation of a battery to terminate discharge of said battery to avoid damage to said battery and substantially maximize use of chemical capacity of said battery as recited in claim 17 wherein said at least one measurable parameter are said battery voltage and age of said battery.

19. An apparatus for controlling operation of a battery to terminate discharge of said battery to avoid damage to said battery and substantially maximize use of chemical capacity of said battery as recited in claim 18 wherein said preestablished data relates depth of discharge for said battery with said battery voltage for a variety of ages of said battery.

20. An apparatus for controlling operation of a battery to terminate discharge of said battery to avoid damage to said battery and substantially maximize use of chemical capacity of said battery as recited in claim 19 wherein said preestablished data is embodied in a family of data representations relating depth of discharge for said battery with said battery voltage for a variety of ages of said battery.