Battery recharge estimator using battery impedance response

Patent metadata

Field	Value
Publication number	US-9252465-B2
Application number	US-201113114336-A
Country	US
Kind code	B2
Filing date	May 24, 2011
Priority date	May 24, 2011
Publication date	Feb 2, 2016
Grant date	Feb 2, 2016

Abstract

An exemplary embodiment includes a method for determining a time to recharge a rechargeable battery system including providing impedance data over a frequency range, said impedance data characterizing the operation of a rechargeable battery within a selected time window; analyzing said impedance data for predetermined behavior of said impedance data indicating an approaching state of discharge of said battery; and, determining from said predetermined behavior of said impedance data whether a recharge of said rechargeable battery is indicated.

First claim

What is claimed is:

1. A method for determining whether a recharge of a rechargeable battery system is indicated comprising:
providing impedance data over a frequency range, said impedance data characterizing operation a rechargeable battery within a selected time window;
analyzing said impedance data for predetermined behavior of said impedance data indicating an approaching state of discharge of said battery; and,
determining from said predetermined behavior of said impedance data whether a recharge of said rechargeable battery indicated; and
recharging said rechargeable battery if a recharge of said rechargeable battery is indicated by said impedance data.

2. The method of claim 1 , wherein said impedance data is calculated from a Fourier transform of current and voltage data characterizing discharge behavior of said battery system.

3. The method of claim 1 , wherein said step of analyzing comprises presenting said impedance data as imaginary impedance versus frequency data and characterizing a slope of said data near zero frequency.

4. The method of claim 3 , wherein said characterizing comprises determining whether said slope is negative.

5. The method of claim 3 , wherein said step of analyzing comprises presenting said impedance data as imaginary impedance versus real impedance plot over said frequency range and characterizing a low frequency portion of said plot.

6. The method of claim 5 , wherein said characterizing comprises determining whether said low frequency portion extends outward of a radius of a semicircle comprising said plot.

7. The method of claim 1 , wherein said step of analyzing comprises presenting said impedance data as imaginary impedance versus real impedance plot over said frequency range and characterizing a low frequency portion of said plot.

8. The method of claim 1 , wherein said rechargeable battery comprises a lithium containing cathode on discharge.

9. The method of claim 1 , wherein said rechargeable battery comprises a vehicle battery system.

10. The method of claim 1 , wherein said steps of providing, analyzing, and determining are implemented by programmable instructions executed by one or more on board vehicle controllers.

11. The method of claim 1 , further comprising determining an estimated time within which said recharge should take place.

12. A method for determining whether a recharge of a rechargeable battery system is indicated comprising:
providing impedance data over a frequency range, said impedance data characterizing operation a rechargeable battery within a selected time window;
analyzing said impedance data for predetermined behavior of said impedance data indicating an approaching state of discharge of said battery; and,
determining from said predetermined behavior of said impedance data whether a recharge of said rechargeable battery is indicated including determining an estimated time within which said recharge should take place; and
recharging said rechargeable battery at said estimated time if a recharge of said rechargeable battery is indicated by said impedance data.

13. The method of claim 12 , wherein said impedance data is calculated from a Fourier transform of current and voltage data characterizing discharge behavior of said battery system.

14. The method of claim 12 , wherein said step of analyzing comprises characterizing a slope of an imaginary portion of said impedance data versus frequency data near zero frequency.

15. The method of claim 14 , wherein said characterizing comprises determining whether said slope is negative.

16. The method of claim 12 , wherein said step of analyzing wherein said step of analyzing comprises presenting said impedance data as imaginary impedance versus real impedance plot over said frequency range and characterizing a low frequency portion of said plot.

17. The method of claim 12 , wherein said rechargeable battery comprises a lithium containing cathode on discharge.

18. The method of claim 12 , wherein said rechargeable battery comprises a vehicle battery system.

19. The method of claim 12 , wherein said steps of providing, analyzing, and determining are implemented by programmable instructions executed by one or more on board vehicle controllers.

20. A vehicle system for determining whether a recharge of a rechargeable battery system is indicated comprising:
an on-board controller in communication with a vehicle battery system, said controller programmed to determine impedance data over a frequency range, said impedance data characterizing operation a rechargeable battery within a selected time window;
said controller further programmed to analyze said impedance data for predetermined behavior of said impedance data indicating an approaching state of discharge of said battery system;
said controller further programmed to determine from said predetermined behavior of said impedance data whether a recharge of said rechargeable battery is indicated;
wherein said controller is further programmed to output at least one of a signal and a numerical value in response to a determination that said recharge is indicated by said impedance data.

Assignees

• Hariharan Krishnan S
• Gm Global Tech Operations Inc

Inventors

• Hariharan Krishnan S

Classifications

• H01M10/48 Primary

  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 title

• Y02T10/7011

  Cross-Sectional Technologies · mapped topic

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• G01R31/3662

  Physics · mapped topic

• Y02E60/10

  Energy storage using batteries · CPC title