Method and apparatus for monitoring discharge of a battery device based on battery self-discharge and discharge over time

• US 5,640,081 A
• Filed: 05/13/1994
• Issued: 06/17/1997
• Est. Priority Date: 05/13/1994
• Status: Expired due to Term

• Current Assignee: Apple Computer Incorporated (Apple Inc.)
• Original Assignee: Apple Computer Incorporated (Apple Inc.)
• Inventors: Austin, Steven E., Kim, Stephen J., Townsley, David B., Blanc, James J.
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): TOATLEY, GREGORY J
• Application Number:
  US08/242,319
• Time in Patent Office: 1,131 Days
• Field of Search: 320/2, 320/43, 320/48, 320/13, 320/19, 320/28, 320/31, 320/35, 331/111, 331/113, 331/143
• US Class Current: 320/127
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/3828 using current integration
• CPC Class Codes: Y10S 320/21 State of charge of battery
• CPC Class Codes: Y10S 331/03 Logic gate active element oscillator

Abstract

A novel battery monitoring device is described. The monitoring device determines amount of battery self-discharge, determines amount of battery discharge from a monitoring circuit, determines amount of battery discharge from a host device when the host device is in a first power consumption mode, and determines amount of battery discharge from the host device when the host device is in a second power consumption mode. The first mode causes greater discharge of the battery during a given period of time than the second mode.

Claims

1. A method for monitoring discharge of a battery comprising:

determining amount of battery self-discharge;

determining amount of battery discharge due to a monitoring circuit;

determining amount of battery discharge due to a host device when said host device is in a first power consumption mode; and

determining amount of battery discharge due to said host device when said host device is in a second power consumption mode, said first power consumption mode causing greater discharge of said battery during a given period of time than said second power consumption mode.

2. The method of claim 1 wherein said first power consumption mode is an on state and said second power consumption mode is an off state.

3. The method of claim 1 further comprising:

determining whether said battery is coupled to said host device.

5. The method of claim 1 further comprising:

measuring voltage across battery terminals of said battery; and

measuring temperature of said battery.

6. The method of claim 1 further comprising:

measuring current drawn by said host device.

7. The method of claim 1 wherein determining amount of battery self-discharge comprises:

calculating battery self-discharge over a specified time interval.

8. The method of claim 1 wherein determining amount of battery discharge due to said monitoring circuit comprises:

calculating battery discharge due to said monitoring circuit over a specified time interval.

9. The method of claim 1 wherein determining amount of battery discharge due to said host device when said host device is in said second power consumption mode comprises:

calculating battery discharge due to said host device over a specified time interval when said battery is coupled to said host device.

10. The method of claim 1 further comprising:

sending a first interrupt signal after a first time interval when said battery is coupled to said host device; and

sending a second interrupt signal after a second time interval when said battery is decoupled from said host device.

11. The method of claim 10 wherein said first time interval is shorter than said second time interval.

12. The method of claim 10 wherein determining amount of battery self-discharge comprises:

calculating battery self-discharge over said first time interval when said battery is coupled to said host device; and

calculating battery self-discharge over said second time interval when said battery is decoupled from said host device.

13. The method of claim 10 wherein determining amount of battery discharge due to said monitoring circuit comprises:

calculating battery discharge due to said monitoring circuit over said first time interval when said battery is coupled to said host device; and

calculating battery discharge due to said monitoring circuit over said second time interval when said battery is decoupled from said host device.

14. The method of claim 10 wherein determining amount of battery discharge due to said host device when said host device is in said second power consumption mode comprises:

calculating battery discharge due to said host device over said first time interval when said battery is coupled to said host device.

15. The method of claim 1 further comprising:

determining amount of battery discharge due to said host device when said host device is in a third power consumption mode.

16. The method of claim 15 wherein determining amount of battery discharge due to a host device when said host device is in said third power consumption mode comprises:

measuring current drawn by said host device; and

calculating battery discharge due to said host device over a specified time interval using a measured value of said current drawn across terminals of said battery.

17. The method of claim 1 further comprising:

determining whether said host device is operating is said first or second power consumption mode.

18. The method of claim 1 further comprising:

determining whether said host device has switched to a full operational mode.

4. A method for monitoring discharge of a battery comprising:

determining amount of battery self-discharge;

determining amount of battery discharge due to a monitoring circuit;

determining amount of battery discharge due to a host device when said host device is in a first power consumption mode; and

determining amount of battery discharge due to said host device when said host device is in a second power consumption mode, said first power consumption mode causing greater discharge of said battery during a given period of time than said second power consumption mode; and

determining whether said battery is coupled to said host device by;

receiving an interrupt signal;

disabling a host interrupt signal line; and

determining whether said interrupt signal still exists.

19. A battery monitoring device for coupling to a battery and a host device, said battery monitoring device comprising:

a current measuring apparatus capable of measuring current drawn by said host device;

a controller coupled to said current measuring apparatus, wherein said controller capable of determining battery self-discharge, determining battery discharge due to a monitoring circuit, determining battery discharge due to a host device when said host device is in a first power consumption mode, determining battery discharge due to said host device when said host device is in a second power consumption mode, said first power consumption mode causing greater discharge of said battery during a given period of time than said second power consumption mode; and

a memory device coupled to said controller and capable of storing battery data.

20. The battery monitoring device of claim 19 further comprising:

a voltage measuring apparatus capable of measuring voltage across terminals of said battery; and

a temperature measuring apparatus capable of measuring temperature of said battery.

21. The battery monitoring device of claim 19 further comprising:

a timer apparatus capable of generating a signal to said controller after a specified duration when said battery is coupled to a host device.

22. The battery monitoring device of claim 21 wherein said timer apparatus further comprises:

a capacitor;

a first resistor coupled to said capacitor capable of delaying discharge of said capacitor;

a first inverter coupled to said capacitor and having a first input, wherein said first inverter capable of applying charge to said capacitor when a first voltage potential on said first input is above a first threshold voltage Of said first inverter and wherein said first inverter capable of removing charge from said capacitor when a second voltage potential on said first input is below a second threshold voltage of said first inverter; and

threshold detection circuitry having a second input and a second output, said second output coupled to said first input of said first inverter and said second input coupled to said capacitor, wherein said threshold detection circuitry capable of applying said first voltage potential on said first input when a third voltage potential on said second input is below a third threshold voltage of said threshold detection circuitry, and wherein said threshold detection circuitry capable of applying said second voltage potential on said first input when a fourth voltage potential on said second input is above said third threshold voltage of said threshold detection circuitry, wherein said third threshold voltage of said threshold detection circuitry is different than said first and second threshold voltages.

23. The battery monitoring device of claim 19 further comprising:

a timer apparatus capable of generating a signal to said controller after a specified duration when said battery is decoupled from a host device.

24. The battery monitoring device of claim 19 wherein said controller further comprises:

an input capable of receiving an interrupt request signal from a host device.

25. The battery monitoring device of claim 24 wherein said controller further comprises:

a disable apparatus capable of disabling said interrupt request signal from said host device.

26. The battery monitoring device of claim 19 wherein said controller further comprises:

a reset device capable of resetting a timer apparatus.

27. The battery monitoring device of claim 19 further comprising:

a battery timer coupled to said controller and capable of transmitting a signal to said controller after a specified time interval.

28. The battery monitoring device of claim 27 wherein the controller further comprises:

an input capable of receiving said signal from said battery timer.

29. The battery monitoring device of claim 19 wherein said memory is capable of storing a value representing amount of charge remaining in said battery.

30. The battery monitoring device of claim 19 wherein said memory device capable of storing a value representing total amount of battery discharge.

31. In a system comprising a host device, a battery monitoring circuit and a battery, a method for monitoring discharge of said battery comprising:

determining whether said host device is operating in a first operating mode;

receiving an interrupt signal;

determining whether said battery is coupled to said host device;

if said battery is coupled to said host device;

determining whether said host device is operating in a second operating mode or a third operating mode;

determining battery discharge due to said host device over a first specified time interval;

determining battery discharge due to battery self-discharge over a second specified time interval; and

determining battery discharge due to said monitoring circuit over a third specified time interval.

32. The method of claim 31, wherein if said battery is not coupled to said host device, said method further comprises the steps of;

determining battery discharge due to battery self-discharge over a fourth specified time interval;

determining battery discharge due to said monitoring circuit over a fifth specified time interval.

33. The method of claim 31, wherein said first, second and third specified time intervals are equivalent.

34. The method of claim 31, wherein said fourth and fifth time intervals are equivalent.

35. The method of claim 31, wherein said fourth and fifth time intervals are different than said first, second and third time intervals.

36. The method of claim 31, wherein said step of determining whether said battery is coupled to said host device further comprises:

disabling a host interrupt signal line; and

determining whether said interrupt signal still exists.

37. The method of claim 31, wherein if said battery is coupled to said host device, said method further comprising the step of:

measuring a current;

comparing said current with a predetermined value; and

determining whether said host device is operating in said first operating mode.

38. The method of claim 31, wherein said step of determining whether said host device is operating in said second operating mode or said third operating mode comprises:

measuring a current;

comparing said current with a predetermined value;

if said current is less than or equal to said predetermined value, said host device is operating in said second operating mode; and

if said current is greater than said predetermined value, said host device is operating in said third operating mode.