System and Method to Determine an Internal Resistance and State of Charge, State of Health, or Energy Level of a Rechargeable Battery

• US 20110172939A1
• Filed: 01/08/2010
• Published: 07/14/2011
• Est. Priority Date: 01/08/2010
• Status: Abandoned Application

• Current Assignee: Lux Aviation Engineering Corporation, Panacis Inc.
• Original Assignee: Panacis Inc.
• Inventors: Uprety, Sandip, McKernan, Edward
• Application Number:
  US12/684,814
• Publication Number:
  US 20110172939A1
• Time in Patent Office: Days
• US Class Current: 702/63
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• CPC Class Codes: H01M 10/486 for measuring temperature
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A battery monitoring system includes a current, voltage, and temperature sensor. The system includes a processor in communication with each of the current, voltage, and temperature sensor that is configured to read a first bulk current of the at least one of a battery and a battery cell at a first time using the current sensor, and, when the first bulk current is less than a first threshold, read a second bulk current of the at least one of a battery and a battery cell at a second time using the current sensor. When the second bulk current has a value between a second threshold and a third threshold and the difference between the first time and the second time is less than a pre-determined delay threshold, the processor is configured to use the first and second bulk current values to determine an internal resistance of the battery or cell.

Claims

1. A battery monitoring system, comprising:

a current sensor configured to measure a bulk current of at least one of a battery and a battery cell;

a voltage sensor configured to measure a terminal voltage of the at least one of a battery and a battery cell;

a temperature sensor configured to measure a temperature of the at least one of a battery and a battery cell; and

a processor in communication with each of the current sensor, voltage sensor, and temperature sensor, the processor being configured to;

read a first bulk current of the at least one of a battery and a battery cell at a first time using the current sensor, and,

when the first bulk current is less than a first threshold, read a second bulk current of the at least one of a battery and a battery cell at a second time using the current sensor, and

when the second bulk current has a value between a second threshold and a third threshold and the difference between the first time and the second time is less than a pre-determined delay threshold, use the first and second bulk current values to determine an internal resistance of the battery or cell.

2. The battery monitoring system of claim 1, wherein the processor is configured to:

read a first terminal voltage of the at least one of a battery and a battery cell at the first time using the voltage sensor; and

,

when the first bulk current is less than the first threshold, read a second terminal voltage of the at least one of a battery and a battery cell at the second time using the voltage sensor.

3. The battery monitoring system of claim 1, wherein the processor is configured to:

determine a difference between the second bulk current and the first bulk current; and

use the difference to determine a discharge rate compensation factor for the internal resistance of the at least one of a battery and a battery cell.

4. The battery monitoring system of claim 1, wherein the processor is configured to determine a state of health (SOH) of the at least one of a battery and a cell.

5. The battery monitoring system of claim 1, wherein the processor is configured to determine a state of charge (SOC) of the at least one of a battery and a cell.

6. The battery monitoring system of claim 1, wherein the processor is configured to determine a battery energy level (BEL) of the at least one of a battery and a cell.

7. The battery monitoring system of claim 1, wherein the first threshold is a number of amps (A) approximately equal to a value of one-third of a numerical value of an amp-hour capacity of the at least one of a battery and a cell.

8. The battery monitoring system of claim 1, wherein the second threshold is a number of amps (A) approximately equal to a value of one-half a numerical amp-hour capacity of the at least one of a battery and a cell.

9. The battery monitoring system of claim 1, wherein the third threshold is a number of amps (A) approximately equal to a value of three times a numerical amp-hour capacity of the at least one of a battery and a cell.

10. A battery monitoring system, comprising:

a memory for storing data; and

a processor for communicating with each of a current sensor, voltage sensor, and temperature sensor, the processor being configured to;

record load current values and terminal voltage values of at least one of a battery and a cell in the memory,

detect a step change in load current of the at least one of a battery and a cell, the step change beginning at a first time and ending at a second time,

use a first load current value and a first terminal voltage value of the at least one of a battery and a cell detected at the first time, and a second load current value and a second terminal voltage value of the at least one of a battery and a cell detected at the second time to determine an internal resistance of the at least one of a battery and cell.

11. The battery monitoring system of claim 10, wherein the processor is configured to determine whether the difference between the first time and the second time is less than a delay threshold.

12. The battery monitoring system of claim 10, wherein the processor is configured to:

determine a difference between the second load current value and the first load current value; and

use the difference to determine a discharge rate compensation of the internal resistance of the at least one of a battery and a battery cell.

13. The battery monitoring system of claim 10, wherein the processor is configured to determine a state of health (SOH) of the at least one of a battery and a cell.

14. The battery monitoring system of claim 10, wherein the processor is configured to determine a state of charge (SOC) of the at least one of a battery and a cell.

15. The battery monitoring system of claim 10, wherein the processor is configured to determine a battery energy level (BEL) of the at least one of a battery and a cell.

16. A battery monitoring system comprising a processor, a computer readable medium, a current sensor, a temperature sensor, a voltage sensor, and computer readable program code encoded in the computer readable medium to monitor the status of at least one of a battery and a battery cell, the computer readable program code comprising a series of computer readable program steps to effect:

reading a first bulk current of the at least one of a battery and a battery cell at a first time;

when the first bulk current is less than a first threshold, reading a second bulk current of the at least one of a battery and a battery cell at a second time; and

when the second bulk current has a value between a second threshold and a third threshold and the difference between the first time and the second time is less than a delay threshold, using the first and second bulk current values to determine an internal resistance of the battery or cell.

17. The battery monitoring system of claim 16, wherein the computer readable program code includes a series of computer readable program steps to effect:

reading a first terminal voltage of the at least one of a battery and a battery cell at the first time; and

,

when the first bulk current is less than a first threshold, reading a second terminal voltage of the at least one of a battery and a battery cell at the second time.

18. The battery monitoring system of claim 16, wherein the computer readable program code includes a series of computer readable program steps to effect:

determining a difference between the second bulk current and the first bulk current; and

using the difference to determine a discharge rate compensation of the internal resistance of the at least one of a battery and a battery cell.

19. The battery monitoring system of claim 16, wherein the first threshold is a number of amps (A) approximately equal to a value of one-third a numerical amp-hour capacity of the at least one of a battery and a cell.

20. The battery monitoring system of claim 16, wherein the second threshold is a number of amps (A) approximately equal to a value of one-half a numerical amp-hour capacity of the at least one of a battery and a cell.

21. The battery monitoring system of claim 16, wherein the third threshold is a number of amps (A) approximately equal to a value of three times a numerical amp-hour capacity of the at least one of a battery and a cell.

22. A battery monitoring system comprising a processor, a computer readable medium, a current sensor, a temperature sensor, a voltage sensor, and computer readable program code encoded in the computer readable medium to monitor the status of at least one of a battery and a battery cell, the computer readable program code comprising a series of computer readable program steps to effect:

recording load current values and terminal voltage values of at least one of a battery or cell in the memory;

detecting a step change in load current of the at least one of a battery and a cell, the step change beginning at a first time and ending at a second time; and

using a first load current value and a first terminal voltage value detected at the first time, and a second load current value and a second terminal voltage value detected at the second time to determine an internal resistance of the at least one of a battery and cell.

23. The battery monitoring system of claim 22, wherein the computer readable program code includes a series of computer readable program steps to effect determining whether the difference between the first time and the second time is less than a delay threshold.

24. The battery monitoring system of claim 22, wherein the computer readable program code includes a series of computer readable program steps to effect:

determining a difference between the second load current value and the first load current value; and

using the difference to determine a discharge rate compensation of the internal resistance of the at least one of a battery and a battery cell.