LITHIUM-ION BATTERY PROGNOSTIC TESTING AND PROCESS

• US 20080094031A1
• Filed: 10/18/2006
• Published: 04/24/2008
• Est. Priority Date: 10/18/2006
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Singh, Harmohan N., Johnson, James S.
• Granted Patent: US 7,576,545 B2
• Time in Patent Office: Days
• US Class Current: 320/132
• CPC Class Codes: G01R 31/387 Determining ampere-hour charge capacity or SoC
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 10/42 Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells H01M10/60 takes precedence
• CPC Class Codes: H01M 10/4285 Testing apparatus
• 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
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

In accordance with various embodiments, there are systems and methods for predicting end of life of a Li-ion battery. The method can include at least one of partially charging and partially discharging a battery, measuring an open circuit voltage of the battery before and after at least one of partial charging and partial discharging, and determining a state of charge value of the battery corresponding to the open circuit voltage measured before and after at least one of partial charging and partial discharging. The method can also include correlating at least one of a charge energy and a discharge energy with a change in the state of charge value and extrapolating to get a full battery capacity, tracking the full battery capacity as a function of time, and performing trend analysis of the full battery capacity over time to predict the battery'"'"'s end of life.

Claims

1. A method for determining full capacity of a Li-ion battery comprising:

partially charging a battery with a known state of charge by applying a constant current;

measuring an open circuit voltage of the battery before and after the step of partial charging;

determining a state of charge value of the battery corresponding to the open circuit voltage measured before and after the step of partial charging; and

correlating a charge energy with a change in the state of charge to determine a full capacity of the battery;

wherein the charge energy is the energy required for charging at a constant current until the voltage across the battery reaches a predetermined value; and

wherein the change in the state of the charge is the difference in the state of charge value of the battery before and after the partial charge.

2. The method according to claim 1, wherein the step of partial charging further comprises selecting a partial charge region from at least one of a charge and a discharge curve.

3. The method according to claim 2, wherein the step of partial charging further comprises selecting the partial charge region from the steepest region of at least one of the charge and discharge curves.

4. The method according to claim 1, wherein the battery is charged at a charge rate of about 0.1 C to about 1 C.

5. The method according to claim 1, wherein the state of charge value of the battery is determined by at least one of looking at a graph and a look up table of a state of charge versus open circuit voltage of the battery.

6. The method according to claim 1 further comprising depolarizing the battery before the partial charge.

7. The method according to claim 1 further comprising determining full capacity as a function of temperature.

8. A method for determining full capacity of a Li-ion battery comprising:

partially discharging a battery with a known state of charge by applying a load;

measuring an open circuit voltage of the battery before and after the step of partial discharging;

determining a state of charge value of the battery corresponding to the open circuit voltage measured before and after the step of partial discharging; and

correlating a discharge energy with a change in the state of charge to determine the full capacity of the battery;

wherein the discharge energy is the energy required for discharging until the voltage across the battery reaches a predetermined value; and

wherein the change in the state of the charge is the difference in the state of charge value of the battery before and after the partial discharge.

9. The method according to claim 8, wherein the step of partial discharging further comprises selecting a partial discharge region from at least one of a charge and a discharge curve.

10. The method according to claim 9, wherein the step of partial discharging further comprises selecting the partial discharge region from the steepest region of at least one of the charge and discharge curves.

11. The method according to claim 8, wherein the load applied is constant.

12. The method according to claim 8, wherein the load applied has a predetermined profile.

13. The method according to claim 8, wherein the state of charge value of the battery is determined by at least one of looking at a graph and a look up table of a state of charge versus open circuit voltage of the battery.

14. The method according to claim 8 further comprising determining full capacity as a function of temperature.

15. A method for predicting end of life of a Li-ion battery comprising:

at least one of partially charging and partially discharging a battery;

measuring an open circuit voltage of the battery before and after the step of at least one of partial charging and partial discharging;

determining a state of charge value of the battery corresponding to the open circuit voltage measured before and after the step of at least one of partial charging and partial discharging;

correlating at least one of a charge energy and a discharge energy with a change in the state of charge value and extrapolating to get a full battery capacity, wherein the charge energy or discharge energy is the energy required for partial charging or partial discharging and the change in the state of the charge is the difference in the state of charge value before and after at least one of the partial charge or partial discharge;

recording and tracking the battery'"'"'s full capacity as a function of time; and

performing trend analysis of the battery'"'"'s full capacity over time to predict the battery'"'"'s end of life.

16. The method of claim 15, wherein the step of at least one of partially charging and partially discharging a battery further comprises selecting at least one of a partial charge region and a partial discharge region from the steepest region of at least one of a charge and a discharge curve.

17. The method of claim 15, wherein the step of performing trend analysis comprises determining whether the battery'"'"'s full capacity has declined by a certain amount, wherein the certain amount depends upon the application in which the battery is used.

19. A system of claim 15, further comprising a temperature sensor for measuring a temperature of the battery.

18. A system for predicting end of life of a Li-ion battery comprising:

an instrumentation and control module comprising an analog-to-digital converter, a digital-to-analog converter, and an electronics control signal generator;

a power supply that supplies a current to partially charge the battery;

a current sensor disposed in series between the power supply and the battery to measure a current passing to the battery from the power supply;

a load to partially discharge the battery;

a current sensor disposed in series between the load and the battery to measure the current passing through the load;

a voltage sensor electrically connected to the battery to measure an open circuit voltage of the battery before and after at least one of a partial charge and a partial discharge of the battery;

a computer with a processor that determines the full capacity of the battery, prepares a trend analysis of the battery'"'"'s full capacity as a function of time, and predicts battery'"'"'s end of life.

20. A computer readable medium comprising program code that configures a processor to perform a method for predicting end of life of a Li-ion battery, said program code comprising:

a program code for at least one of partial charging and partial discharging the battery;

a program code for measuring an open circuit voltage of the battery before and after the step of at least one of partial charging or partial discharging;

a program code for determining a state of charge value of the battery corresponding to the open circuit voltage measured before and after the step of at least one of partial charging or partial discharging;

a program code for correlating at least one of a charge energy and a discharge energy with a change in state of charge and extrapolating to get the battery'"'"'s full capacity; and

a program code for performing trend analysis of the battery'"'"'s full capacity over time to predict the battery'"'"'s end of life.