MONITORING BATTERY HEALTH IN AN HVAC SYSTEM

• US 20110029193A1
• Filed: 07/30/2010
• Published: 02/03/2011
• Est. Priority Date: 07/31/2009
• Status: Active Grant

• Current Assignee: Thermo King Corporation (Trane Technologies plc)
• Original Assignee: Thermo King Corporation (Trane Technologies plc)
• Inventors: Brabec, Ladd J., Shaw, John J., Abbott, Phillip M., Musich, Matthew A.
• Granted Patent: US 8,423,238 B2
• Time in Patent Office: Days
• US Class Current: 701/35
• CPC Class Codes: G01R 31/3828 using current integration
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health

Abstract

Systems and methods of monitoring battery health in an HVAC system. The charge state of a rechargeable battery and the number of amp-hours provided to or from the rechargeable battery are monitored. The number of amp-hours provided is recorded and an end-of-life condition is detected based on the number of amp-hours provided during the charge or discharge cycle. In some constructions, the end-of-life condition is detected by comparing the number of amp-hours provided during the charge or discharge cycle to a threshold. In some constructions, the end-of-life condition is detected by calculating a rate of change of the number of amp-hours provided during a charge or discharge cycle and comparing the rate of change to a threshold.

Claims

1. A control system for an HVAC system, the control system comprising a processor and a computer readable memory storing instructions that, when executed by the processor, cause the control system to:

monitor a charge state of a battery;

monitor at least one of a number of amp-hours provided by the battery during usage and a number of amp-hours provided to the battery during charging;

detect when the battery is in a first charge state;

detect when the battery is in a second charge state;

record a number of amp-hours provided during at least one of a discharge cycle and a charge cycle, the discharge cycle including depleting the battery from the first charge state to the second charge state without any intervening charging of the battery, and the charge cycle including charging the battery from the second charge state to the first charge state without any intervening usage of the battery; and

detect an end-of-life condition of the battery based on at least one of the number of amp-hours provided by the battery during the discharge cycle and the number of amp-hours provided to the battery during the charge cycle.

2. The control system of claim 1, wherein the instructions, when executed by the processor, cause the control system to detect the end-of-life condition by comparing the number of amp-hours provided by the battery during the at least one of the discharge cycle and the charge cycle to a threshold.

3. The control system of claim 1, wherein the instructions, when executed by the processor, further cause the control system to record a number of amp-hours provided by the battery during each of a plurality of discharge cycles and cause the control system to detect the end-of-life condition by

calculating a rate of change of the number of amp-hours provided by the battery during a discharge cycle;

and

comparing the rate of change to a threshold.

4. The control system of claim 1, wherein the instructions, when executed by the processor, further cause the control system to record a number of amp-hours provided to the battery during each of a plurality of charge cycles and cause the control system to detect the end-of-life condition by

calculating a rate of change of the number of amp-hours provided to the battery during a charge cycle;

and

comparing the rate of change to a threshold.

5. The control system of claim 1, wherein the instructions, when executed by the processor, further cause the control system to

record a total number of amp-hours provided by the battery;

record a number of full and partial discharge cycles provided by the battery; and

monitor battery voltage.

6. The control system of claim 1, wherein the battery is fully charged when in the first charge state and is storing less than 20% of a full charge when in the second charge state.

7. The control system of claim 1, wherein the instructions, when executed by the processor, further cause the control system to

detect whether the control system is connected to an external power source;

and

charge the battery and provide power to the HVAC system from the external power source when the control system is connected to the external power source.

8. A vehicle comprising the control system of claim 1, an HVAC system, an alternator, and a rechargeable battery all coupled to the control system.

9. The vehicle of claim 8, wherein the instructions, when executed by the processor, further cause the control system to determine whether the vehicle is running and to charge the battery and provide power to the HVAC system from a vehicle alternator when the vehicle is running.

10. A method of monitoring battery health in an HVAC system comprising:

monitoring a charge state of a battery;

monitoring at least one of a number of amp-hours provided by the battery during usage and a number of amp-hours provided to the battery during charging;

detecting when the battery is at a first charge state;

detecting when the battery is at a second charge state;

recording a number of amp-hours provided during at least one of a discharge cycle and a charge cycle, the discharge cycle including depleting the battery from the first charge state to the second charge state without any intervening charging of the battery, and the charge cycle including charging the battery from the second charge state to the first charge state without any intervening usage of the battery; and

detecting an end-of-life condition of the battery based on at least one of the number of amp-hours provided by the battery during the discharge cycle and the number of amp-hours provided to the battery during the charge cycle.

11. The method of claim 10, wherein the act of detecting an end-of-life condition of the battery includes comparing the number of amp-hours provided by the battery during the at least one of the discharge cycle and the charge cycle to a threshold.

12. The method of claim 10, further comprising recording a number of amp-hours provided by the battery during each of a plurality of discharge cycles and wherein the act of detecting an end-of-life condition of the battery includes

calculating a rate of change of the number of amp-hours provided by the battery during a discharge cycle;

and

comparing the rate of change to a threshold.

13. The method of claim 10, further comprising recording a number of amp-hours provided to the battery during each of a plurality of charge cycles and wherein the act of detecting an end-of-life condition of the battery includes

calculating a rate of change of the number of amp-hours provided to the battery during a charge cycle;

and

comparing the rate of change to a threshold.

14. The method of claim 10, wherein the battery is fully charged when at the first charge state and is holding less than 20% of a full charge when in the second charge state.

15. The method of claim 10, wherein the HVAC system is installed in a vehicle, and further comprising:

detecting whether the control system is connected to an external power source;

charging the battery from the external power source when the control system is connected to the external power source; and

powering the HVAC system from the external power source when the vehicle is connected to the external power source.

16. The method of claim 10, wherein the HVAC system is installed in a vehicle, and further comprising:

determining whether the vehicle is running;

charging the battery from a vehicle alternator when the vehicle is running; and

powering the HVAC system from the vehicle alternator when the vehicle is running.

17. A control system for an HVAC system, the control system comprising a processor and a computer readable memory storing instructions that, when executed by the processor, cause the control system to:

monitor a charge state of a battery;

monitor a number of amp-hours provided by the battery to the HVAC system;

detect when the battery is in a full-charge state;

detect when the battery is in a full-discharge state;

record a number of amp-hours provided by the battery during a complete discharge cycle, wherein the complete discharge cycle includes depleting the battery from the full-charge state to the full-discharge state without any intervening charging of the battery; and

detect an end-of-life condition of the battery based on the number of amp-hours provided by the battery during the complete discharge cycle.

18. The control system of claim 17, wherein the battery is in the full-discharge state when the remaining charge is less than 20% of a full charge.

19. A vehicle comprising:

an HVAC system;

an alternator;

a rechargeable battery; and

the control system of claim 17, wherein the instructions, when executed by the processor, further cause the control system to

detect when the vehicle is running,

charge the battery from electricity provided by the alternator when the vehicle is running,

power the HVAC system with electricity provided by the rechargeable battery when the vehicle is not running, and

detect the end-of-life condition of the battery by

comparing the number of amp-hours provided by the battery during a complete discharge cycle to a first threshold,

calculating a rate of change of the number of amp-hours provided by the battery during a complete discharge cycle, and

comparing the rate of change to a second threshold.