Apparatus and method for maintaining a threshold value in a battery

• US 6,249,106 B1
• Filed: 09/21/2000
• Issued: 06/19/2001
• Est. Priority Date: 09/21/2000
• Status: Expired due to Fees

• Current Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Rajashekara, Kaushik, Turner, Steven Richard, Strickland, Tracy Frye
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): TIBBITS, PIA FLORENCE
• Application Number:
  US09/666,581
• Time in Patent Office: 271 Days
• Field of Search: 320/127, 320/134, 320/135, 320/136
• US Class Current: 320/136
• CPC Class Codes: H02J 7/00306 Overdischarge protection
• CPC Class Codes: H02J 7/0032 disconnection of loads if battery is not under charge, e.g. in vehicle if engine is not running
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]

Abstract

A battery protection system for a battery having a switching mechanism positioned intermediate to the positive terminal and an electrical load of the battery. A controller manipulates the switching mechanism between an open position and a closed position, the closed position connects the electrical load to the battery and the open position disconnects the electrical load from the battery. The battery protection system utilizes a battery state-of-charge detection system, which instructs the controller to open the switching mechanism when the detection system detects a battery state-of-charge that is lower than a threshold value. The battery protection system is also equipped with a vehicle status detection system, which instructs the controller to close the switching mechanism when a vehicle startup condition is detected by the vehicle status detection system.

Claims

1. A battery discharge protection system comprising:

a) a microprocessor being capable of receiving a plurality of inputs, said inputs corresponding to signals from a vehicle;

b) a plurality of electronic switches being configured for movement between an open position and a closed position, said closed position connecting an electrical load to said battery, said open position disconnecting said electrical load from said battery; and

c) a gate input circuit for manipulating said switches between said open and closed positions in response to an output received from said microprocessor.

2. A battery protection system for a battery, comprising:

a) a switching mechanism positioned intermediate to the positive terminal of a battery and an electrical load;

b) a controller for manipulating said switching mechanism between an open position and a closed position, said closed position connecting said electrical load to said battery and said open position disconnecting said electrical load from said battery; and

c) a battery state-of-charge detection system, said battery state-of-charge protection system instructs said controller to open said switching mechanism when said battery state-of-charge detection system detects a battery state-of-charge that is lower than a threshold value.

3. A battery protection system as in claim 2, further comprising:

d) a vehicle status detection system, said vehicle status detection system instructs said controller to close said switching mechanism when a vehicle startup condition is detected by said vehicle status detection system.

4. A battery protection system as in claim 2, further comprising:

d) a manual override switch for disconnecting said battery from said electrical load.

5. A battery protection system as in claim 2, wherein said state of charge protection system instructs said controller to close said switching mechanism when a battery re-connect condition is detected by said vehicle status detection system.

6. A battery protection system as in claim 5, wherein said battery re-connect condition is a depression of a brake pedal which illuminates a taillight, the illumination of said taillight causing a current fluctuation which is detected by said state of charge protection system.

7. A battery protection system as in claim 6, wherein said vehicle startup condition is the movement of an ignition switch from an off position to a start position, said start position causes a starter motor to activate, the activation of said starter motor causes a current fluctuation which is detected by said vehicle status detection system.

8. A battery protection system as in claim 5, wherein said vehicle startup condition is the opening of a car door which illuminates an interior light, the illumination of said interior light causes a current fluctuation which is detected by said vehicle status detection system.

9. A battery protection system as in claim 2, further comprising:

d) a vehicle status detection system, said vehicle status detection system instructs said controller to close said switching mechanism when a vehicle startup condition is detected by said vehicle status detection system; and

e) a controller bypass system, said controller bypass system prevents said controller from opening said switching mechanism when a critical vehicle system is in operation.

10. A battery protection system as in claim 9, wherein said critical vehicle system is the activation of a hazard light of an automobile.

11. The battery protection system as in claim 10, wherein said hazard light of said automobile produces an AC waveform across a pair of terminals of said battery and said AC waveform is measured by said vehicle status detection system.

12. A battery protection system as in claim 9, wherein said critical vehicle system is an engine, which is running.

13. The battery protection system as in claim 12, wherein said engine of said automobile produces an AC waveform across a pair of terminals of said battery and said AC waveform is measured by said vehicle status detection system.

14. A method for maintaining a minimal charge value within a battery, comprising:

a) measuring the charge of said battery; and

b) disconnecting said battery from an electrical load when the charge of said battery approaches a minimal threshold value.

15. The method as in claim 14, wherein said minimal threshold value is a minimal charge sufficient to start an automobile engine.

16. The method as in claim 15, wherein a system controller utilizing an electronic switch disconnects said battery from said electrical load.

17. The method as in claim 14, wherein said system controller is prohibited from disconnecting said battery when said battery is installed in an automobile and the engine is running.

18. A device for protecting an automobile lead-acid battery from an over-discharged condition due to an electrical load, said device comprising:

a) an electronic switch interposed between a battery output terminal and any battery electrical load;

b) a means for determining the state-of-charge of said battery as a function of the discharge due to said electrical load;

c) a means for determining the battery voltage below which the continued reduction in said state-of-charge of said battery would result in an over-discharged condition;

d) a means for causing said electronic switch to transition from a closed-circuit condition to an open-circuit condition, thereby preventing said over-discharged condition; and

e) a means for causing said electronic switch to transition from said open-circuit condition to said closed-circuit condition when a fluctuation in said load occurs.

19. The battery protection system as in claim 18, wherein said controller is prohibited from manipulating said switching mechanism when a discrete waveform is detected by said vehicle status detection system.

20. The battery detection system as in claim 19, wherein said discrete waveform is an AC waveform produced by a running automobile engine.

21. The battery detection system as in claim 20, wherein said discrete waveform is an AC waveform produced by flashing hazard lamps of an automobile.

22. A method for maintaining a minimal charge value within a battery, comprising:

a) periodically measuring the charge of said battery;

b) determining a value depicting the time rate of change of a battery voltage;

c) measuring ambient temperature of said battery;

d) comparing the time rate of change of a battery voltage and the ambient temperature reading to a plurality of values stored in a lookup table and determining a minimal threshold value; and

e) disconnecting said battery from an electrical load when the charge of said battery approaches said minimal threshold value.

23. The method as in claim 22, wherein a formula is applied to the time rate of change value and ambient temperature in order to determine said minimal threshold value.

24. A method for maintaining a minimal charge value within a battery, comprising:

a) periodically measuring the charge of said battery;

b) storing the measured charges of said battery;

c) determining a value depicting the time rate of change of a battery voltage;

c) measuring ambient temperature of said battery;

d) comparing the time rate of change of a battery voltage and the ambient temperature reading to a plurality of values stored in a lookup table and determining a minimal threshold value; and

e) disconnecting said battery from an electrical load when the charge of said battery approaches said minimal threshold value.

25. The method as in claim 24, further comprising:

f) prohibiting the disconnection of said battery when a critical vehicle function is enabled.

26. The method as in claim 25 wherein said critical function is an automobile engine.

27. A method for maintaining a minimal charge value within a battery, comprising:

a) determining if a current of a switching mechanism between a battery and a load exceeds a maximum value, if the current of said switching mechanism exceeds a maximum value the battery is disconnected from the load;

b) determining if an automobile engine is running, if the automobile engine is running the current of said switching mechanism is determined again;

c) determining if a hazard lamp of an automobile is operating, if the hazard lamp is enabled the current of said switching mechanism is determined again;

d) overriding a manual shut off switch if said automobile engine is running or said hazard lamp is operating;

e) determining if a maximum temperature of said switching mechanism is exceeded, if the maximum temperature is exceeded the battery is disconnected from the load;

f) comparing a battery voltage and an ambient temperature reading of said battery to a plurality of values stored in a lookup table and determining a minimal threshold value; and

e) disconnecting said battery from an electrical load when the charge of said battery approaches said minimal threshold value.