Battery pack

• US 6,137,264 A
• Filed: 03/20/1998
• Issued: 10/24/2000
• Est. Priority Date: 03/20/1998
• Status: Expired due to Term

• Current Assignee: Maxim Integrated Products, Inc. (Analog Devices, Inc.)
• Original Assignee: Dallas Semiconductor Corporation (Analog Devices, Inc.)
• Inventors: Douglass, James M., Ezell, Richard William, Downs, Richard E.
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US09/045,302
• Time in Patent Office: 949 Days
• Field of Search: 320/127, 320/128, 320/132, 320/133, 320/135, 320/150, 320/155, 320/DIG. 21, 320/149
• US Class Current: 320/133
• CPC Class Codes: H02J 7/00714 in response to battery charging or discharging current
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices

Abstract

A rechargeable battery pack with low powered, gas gauge circuitry for monitoring and accumulating various operating parameters of the rechargeable battery pack, includes a current monitor for measuring the current flow into and out of a battery cell in the rechargeable battery pack. An integrated current accumulator connected to the current monitor is used to maintain a measure of the net charge having flowed into and out of the battery cell. A charging current accumulator, which is also coupled to the current monitor, is used to maintain a measure of the total charge having flowed into the battery cell, while a discharging current accumulator is used to maintain a measure of the total charge having flowed out of the battery cell. A highly accurate oscillator is used to drive the accumulators to greatly increase the accuracy of the gas gauge functions derived therefrom.

Claims

1. A battery pack comprising:

at least one battery cell;

circuitry coupled to said at least one battery cell, said circuitry for monitoring at least one parameter relating to the battery pack; and

a timekeeper coupled to said circuitry, said timekeeper for providing a timing signal to said circuitry;

wherein said circuitry includes a temperature monitor coupled to said timekeeper.

2. The battery pack as recited in claim 1, wherein said circuitry includes a current monitor for measuring at least indications of discharging current from said at least one battery cell at select intervals timed by said timing signal.

3. The battery pack as recited in claim 2, wherein said circuitry includes a first accumulator coupled to said current monitor, said first accumulator for accumulating values representing the total amount of charge having flowed out of said at least one battery cell.

4. The battery pack as recited in claim 2, wherein said at least one battery cell is rechargeable;

and

wherein said current monitor further measures at least indications of the charging current into said at least one battery cell.

5. The battery pack as recited in claim 4, and further comprising a second accumulator coupled to said current monitor, said second accumulator for accumulating values representing the total amount of charge having flowed into said at least one battery cell.

6. The battery pack as recited in claim 4, and further comprising a third accumulator coupled to said current monitor, said third accumulator for accumulating values representing the net amount of charge having flowed into and out of said at least one battery cell.

7. The battery pack as recited in claim 4, wherein said timekeeper generates an end-of-charge timestamp in response to completion of the charging of said at least one battery cell.

8. The battery pack as recited in claim 1, wherein said timekeeper further generates a disconnect timestamp.

9. The battery pack as recited in claim 8, wherein said disconnect timestamp is used to calculate the amount of self-discharge of said at least one battery cell.

10. A battery pack comprising:

at least one battery cell;

a current monitor coupled to said at least one battery cell, said current monitor for measuring the discharging current from the at least one battery cell and for measuring the charging current to the at least one battery cell;

a clock coupled to said current monitor, said clock for generating a clock signal to time said current monitor measuring the discharging current; and

a first accumulator coupled to said current monitor, said first accumulator for accumulating the total amount of charge having flowed out of said at least one battery cell; and

a second accumulator coupled to said current monitor, said second accumulator for accumulating the total amount of charge having flowed into said at least one battery cell.

11. The battery pack as recited in claim 10, and further comprising a third accumulator coupled to said current monitor, said third accumulator for accumulating values representing the net amount of charge having flowed into and out of said at least one battery cell.

12. The battery pack as recited in claim 11, and further comprising a temperature monitor coupled to said clock, said temperature monitor for at least monitoring the temperature of said at least one battery cell.

13. The battery pack as recited in claim 12, and further comprising memory to store an identification code.

14. The battery pack as recited in claim 13, wherein said clock circuit further generates an end-of-charge timestamp in response to a completion of the charging of said at least one battery cell.

15. The battery pack as recited in claim 14, wherein said clock circuit further generates a disconnect timestamp.

16. The battery pack as recited in claim 15, wherein said clock includes a crystal oscillator.

17. A rechargeable battery pack comprising:

at least one rechargeable battery cell;

a current meter coupled to said at least one battery cell, said current meter for measuring the discharge current from said at least one rechargeable battery cell;

a discharge current accumulator coupled to said current meter, said discharge current accumulator for accumulating the total charge having flowed out of said at least one rechargeable battery cell; and

a clock coupled to said current meter, said clock for generating a clock signal to time said current meter measuring the discharge current from said at least one rechargeable battery cell, and further to time said discharge current accumulator accumulating the total charge having flowed out of said at least one rechargeable battery cell;

wherein said current meter is further for measuring charring current into said at least one rechargeable battery cell.

18. The rechargeable battery pack as recited in claim 17, and further comprising a charge accumulator connected to said current meter, said charge accumulator for accumulating the total charge having flowed into said at least one rechargeable battery cell.

19. The rechargeable battery pack as recited in claim 17, and further comprising an integrated current accumulator coupled to said current meter, said integrated current accumulator for accumulating the net total of charge having flowed into and out of said at least one rechargeable battery cell.

20. The rechargeable battery pack as recited in claim 17, wherein said clock includes a crystal oscillator.

21. The rechargeable battery pack as recited in claim 17, wherein said clock further generates an end-of-charge timestamp in response to a completion of the charging of said at least one rechargeable battery cell.

22. The rechargeable battery pack as recited in claim 17, wherein said clock further generates a disconnect timestamp.

23. A battery pack comprising:

at least one rechargeable battery cell;

a current monitor coupled to said at least one rechargeable battery cell, said current monitor for measuring the discharge current from said at least one rechargeable battery cell; and

a clock coupled to said current monitor, said clock for generating a clock signal to time said current monitor measuring the discharge current from said at least one rechargeable battery cell;

wherein said clock includes a crystal oscillator.

24. The battery pack as recited in claim 23, and further comprising a discharge accumulator coupled to said current monitor, said discharge accumulator for accumulating the total amount charge having flowed out of said at least one rechargeable battery cell.

25. The battery pack as recited in claim 23, wherein said current monitor further measures charge current into said at least rechargeable one battery cell.

26. The battery pack as recited in claim 25, and further comprising a charging accumulator coupled to said current monitor, said charging accumulator for accumulating the total amount of charge having flowed into said at least one rechargeable battery cell.

27. The battery pack as recited in claim 25, and further comprising a net current accumulator coupled to said current monitor, said net current accumulator for accumulating the net amount of charge having flowed into and out of said at least one rechargeable battery cell.

28. The battery pack as recited in claim 23, and further comprising a temperature monitor for at least monitoring the temperature of said at least one rechargeable battery cell.

29. The battery pack as recited in claim 23, wherein said clock circuit further generates an end-of-charge timestamp in response to a completion of the charging of said at least one rechargeable battery cell.

30. The battery pack as recited in claim 23, wherein said clock circuit further generates a disconnect timestamp.