Automatic discharge of a failed battery

• US 8,577,630 B2
• Filed: 12/14/2007
• Issued: 11/05/2013
• Est. Priority Date: 12/14/2007
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Heizer, Stephen D., Wozniak, John A., Sawyers, Thomas P.
• Primary Examiner(s): Armand, Marc
• Assistant Examiner(s): SUAREZ, FELIX E
• Application Number:
  US12/747,549
• Publication Number:
  US 20100268494A1
• Time in Patent Office: 2,153 Days
• Field of Search: 702/63, 702/58, 702/60, 702/64
• US Class Current: 702/63
• CPC Class Codes: H01M 10/425 Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing printed circuits H05K1/00
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• 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: H01M 2200/00 Safety devices for primary or secondary batteries
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A system comprises a battery cell, control logic, and a battery drain latch circuit. The control logic is coupled to the battery cell and determines whether a battery pack has experienced a failure condition. The battery drain latch circuit is activated by the control logic, upon detection of a failure condition, to cause the battery cell to drain energy therefrom.

Claims

1. A system, comprising:

a battery cell;

control logic coupled to the battery cell, said control logic determines whether a battery pack has experienced a failure condition; and

a battery drain latch circuit that is activated by said control logic, upon detection of the failure condition, to cause said battery cell to drain energy.

2. The system of claim 1 wherein said battery drain latch circuit comprises a two-transistor latch.

3. The system of claim 1 wherein said battery drain latch circuit receives an input failure signal from said control logic, said input failure signal indicating an occurrence of the failure condition.

4. The system of claim 3 wherein said battery drain latch circuit continues to cause energy to be drained from said battery cell even upon a deassertion of the input failure signal.

5. The system of claim 1 wherein said battery drain latch circuit is electrically connected to a terminal of the battery cell.

6. The system of claim 1 wherein said control logic comprises a voltage regulator that provides a regulated voltage from said control logic, and wherein the battery drain latch circuit is electrically connected to a terminal of the voltage regulator.

7. The system of claim 1 wherein said battery drain latch circuit causes said battery cell to drain all of said energy in said battery cell, or all but 1% or less of said energy in said cell.

8. The system of claim 1 wherein said battery drain latch circuit comprises a resistor that dissipates energy drained from said battery cell.

9. The system of claim 1 further comprising host logic that receives operational power from said battery cell.

10. A system, comprising:

a microcontroller to detect a failure condition of a battery pack; and

a battery drain circuit to automatically causing the battery pack to dissipate energy contained therein based on the detection of a failure condition by the microcontroller.

11. The system of claim 10 wherein the battery drain circuit is also for activating a latch.

12. The system of claim 11 wherein the battery drain circuit is to dissipate energy through a resistor.

13. The system of claim 10 wherein the battery drain circuit is also for dissipating energy from a voltage regulator in the battery pack.

14. A method, comprising:

detecting a failure condition of a battery pack;

as a result of detecting the failure condition, asserting a failure signal to a latch; and

the latch causing energy to automatically be drained from the battery pack.

15. The method of claim 14 further comprising the latch continuing to cause the battery pack to continue to be drained upon deassertion of the failure signal.

16. The method of claim 15 wherein the latch causing energy to automatically be drained from the battery pack comprises dissipating energy through a resistor in the latch.

17. The method of claim 15 wherein the latch causing energy to automatically be drained from the battery pack comprises dissipating energy from a voltage regulator in said battery pack.