Battery charger capable of evaluating battery charge state based on the charging history of the battery

• US 6,331,761 B1
• Filed: 11/13/2000
• Issued: 12/18/2001
• Est. Priority Date: 06/22/1998
• Status: Expired due to Term

• Current Assignee: Stryker Corporation
• Original Assignee: Stryker Corporation
• Inventors: Kumar, Yashdeep, Malackowski, Donald
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US09/711,845
• Time in Patent Office: 400 Days
• Field of Search: 320/106, 320/116, 320/119, 320/124, 320/125, 320/132, 320/149, 320/DIG.19, 320/DIG.21, 324/426, 324/427, 324/428, 324/433, 324/434
• US Class Current: 320/132
• CPC Class Codes: A61B 2017/00734 battery operated
• CPC Class Codes: H01M 10/4257 Smart batteries, e.g. electronic circuits inside the housing of the cells or batteries
• CPC Class Codes: H02J 2310/22 The load being a portable electronic device
• CPC Class Codes: H02J 2310/23 The load being a medical device, a medical implant, or a life supporting device
• CPC Class Codes: H02J 7/00036 Charger exchanging data with battery
• CPC Class Codes: H02J 7/00047 with provisions for charging different types of batteries
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A battery charger (20) for charging batteries that evaluates the post-charge state of the batteries. A load resistor (70) is associated with each battery. After the charging of the battery, a processor (124) receives signals indicating the voltage-at-load of the battery when it is connected to the load resistor. A memory (282) internal to the battery stores data indicating the number of times the battery has been charged. The processor, based on the data retrieved from the battery memory determines a minimum charge level for the battery based on the number of times the battery has been charged. Based on the voltage-at-load, the processor determines the charge in the battery and compares this charge to the minimum level. The processor then actuates a display (34) on the charger to indicate the results of this comparison. The processor also actuates a display component (32) to cause the charger to indicate the charge state of the battery relative to the amount of charge a new, fully charged battery can store.

Claims

1. A rechargeable battery pack comprising:

a housing;

at least one rechargeable cell disposed in said housing;

a first set of terminals attached to said housing that is attached to said at least one rechargeable cell, wherein energy is applied to said first set of terminals for storage in said at least one rechargeable cell and current is drawn from said at least one rechargeable cell through said first set of terminals;

a memory disposed in said housing, said memory having a first data field in which data representative of the number of times the battery has been charged are stored and a plurality of second data fields in which data representative of the energy stored in the battery after charging are stored; and

a second set of terminals attached to said housing and connected to said memory, wherein the data representative of the number of times the battery has been charged and the data representative of the energy stored in the battery are written to said memory and read from said memory through said second set of terminals.

2. The rechargeable battery of claim 1, wherein one terminal of said first set of terminals functions is a ground terminal for signals exchanged over said second set of terminals.

3. The rechargeable battery of claim 1, further including a temperature sensor internal to said battery, wherein said temperature sensor generates a temperature signal representative of battery temperature.

4. The rechargeable battery of claim 3, wherein said temperature sensor outputs said temperature signal over said second set of terminals.

5. A method of monitoring the utility of a rechargeable battery, said method including the steps of:

providing a rechargeable battery, the battery having a memory in which data are written to and read from;

fully charging the battery wherein, as part of said charging step, data are read from the memory to determine the number of times the battery was previously charged;

after said charging of said battery, writing into the memory new data indicating the number of times the battery has been charged;

determining the stored energy in the battery when the battery is fully charged;

writing into the memory the determined stored energy of the battery so that the memory contains data indicating the stored energy of the battery after the battery has been charged a plural number of times; and

after plural said chargings of the battery, reading from the memory the data indicating the number of times the battery has been charged and the data indicating the stored energy in the battery after said chargings.

6. The method of monitoring the utility of a battery of claim 5, wherein, said determination of battery stored energy is performed by:

measuring the voltage-at-load of the battery after the battery is fully charged; and

, based on the voltage-at-load of the battery, making a determination of the stored energy in the battery.

7. A method of monitoring the utility of a rechargeable battery, said method including the steps of:

providing a rechargeable battery, the battery having a memory in which data are written to and read from;

fully charging the battery wherein, as part of said charging step, data are read from the memory to determine the number of times the battery was previously charged;

after said fully charging of said battery, writing into the memory new data indicating the number of times the battery has been charged;

determining the stored energy in the battery after said full charging of the battery; and

displaying information to indicate the number of times the battery has been charged and the stored energy in the battery.

8. The method of monitoring the utility of a battery of claim 7, wherein, said determination of battery stored energy is performed by:

measuring the voltage-at-load of the battery after the battery is fully charged; and

, based on the voltage-at-load of the battery, making a determination of the stored energy in the battery.

9. The method of monitoring the utility of a battery of claim 7, wherein in said step of displaying information, information about the stored energy of the battery is presented by displaying an indication of the stored energy of the battery relative to the stored energy in a new, fully-charged stored battery.

10. A method of charging a rechargeable battery, said method including the steps of:

providing a rechargeable battery, the battery having a memory in which data are written into and read from;

charging the battery wherein, in a charging cycle, data are read from the battery to determine the number of times the battery was previously charged;

determining the stored energy in the battery;

based on the data read from the battery indicating the number of times the battery has been previously charged, determining a minimum stored energy level for the battery;

comparing the stored energy in the battery to the minimum stored energy level for the battery;

generating a display to indicate the results of said comparison; and

writing into the battery memory new data indicating the number of times the battery has been charged.

11. The method of charging a battery of claim 10, wherein:

said steps of;

charging the battery;

determining the stored energy of the battery;

comparing the stored energy in the battery to the minimum stored energy level for the battery;

displaying the results of said comparison; and

writing into the battery memory are performed by a charger to which the battery is removably coupled; and

the charger performs said step of determining the minimum stored energy level for the battery by reading data representative of a stored energy level-to-battery chargings relationship from a memory that is removably coupled to the charger.

12. The method of charging a battery of claim 11, further including the steps of:

removably attaching a module to the charger, the module having a socket adapted to receive the battery, conductors for establishing an electrical connection between the charger and the battery and a module memory wherein, the module memory contains the data representative of the stored energy level-to-battery chargings relationship;

reading with said charger the data representative of the stored energy level-to-battery chargings relationship from the module memory; and

seating the battery in the module socket in order to perform said charging step.

13. The method of charging a battery of claim 10, wherein said step of determining the stored energy of the battery is performed by:

measuring the voltage-at-load of the battery after said step of charging the battery; and

, based on the voltage-at-load of the battery, making a determination of the stored energy of the battery.

14. The method of charging a battery of claim 10, wherein said step of displaying the results of said comparison is performed by selectively actuating a display element as a function of the results of said comparison.

15. A method of charging a rechargeable battery, said method including the steps of:

providing a rechargeable battery, the battery having a memory in which data are written into and read from the battery memory containing data indicating the number of times the battery has been charged;

attaching the battery to a charger, the charger having a display;

reading from the memory into the charger the data indicating the number of times the battery has been charged;

charging the battery with the charger;

after said charging of the battery, determining the stored energy in the battery;

based on the data read from the battery indicating the number of times the battery has been charged, determining with the charger a minimum stored energy level for the battery;

comparing with said charger the stored energy in the battery to the minimum stored energy level for the battery;

actuating the charger display to indicate the results of said comparison; and

writing into the battery memory from the charger new data indicating the number of times the battery has been charged.

16. The method of charging a battery of claim 15, wherein the charger performs said step of determining the minimum stored energy level for the battery by reading data representative of a stored energy level-to-battery chargings relationship from a memory that is removably coupled to the charger.

17. The method of charging a battery of claim 16, further including the steps of:

removably attaching a module to the charger, the module having a socket adapted to receive the battery, conductors for establishing an electrical connection between the charger and the battery and a module memory wherein, the module memory contains the data representative of the stored energy level-to-battery chargings relationship;

reading with the charger the data representative of the minimum stored energy level-to-battery chargings relationship from the module memory; and

seating the battery in the module socket in order to perform said charging step.

18. The method of charging a battery of claim 15, wherein said step of determining the stored energy of the battery is performed by:

measuring the voltage-at-load of the battery after said step of charging the battery; and

, based on the voltage-at-load of the battery, making a determination of the stored energy of the battery.

19. A charger for providing energization current to a battery, the battery having a memory, said charger having:

a base unit having a display;

a current source disposed in said base unit configured to be connected to the battery for supplying a charging current to the battery; and

a processor disposed in said base unit, said processor being connected to;

said current source for regulating the application of current by said current source to the battery;

the battery for determining the charge stored in the battery;

the battery memory for reading from the battery memory data indicating the number of times the battery has been charged and for writing to the battery memory data indicating the number of times the battery has been charged; and

to said display, and said processor is configured to;

regulate the charging of the battery by said current source;

determine the stored energy of the battery;

based on the number of times the battery has been charged based on the data read from the battery memory, determine a minimum stored energy level for the battery;

compare the stored energy in the battery to the minimum stored energy level;

actuate said display to indicate the results of the comparison; and

write into the battery memory new data that indicates the number of times the battery has been charged.

20. The charger of claim 19, wherein said processor determines the minimum stored energy level for the battery by reading data representative of a stored energy level-to-battery chargings relationship from a memory that is removably coupled to the charger.

21. The charger of claim 20, further including:

a module that is removably attached to said base unit, said module having;

a socket adapted to receive the battery;

conductors for establishing electrical connections between said current source and said processor and the battery; and

a module memory wherein, the module memory contains the data representative of the stored energy level-to-battery chargings relationship; and

wherein, said processor is further configured to read the data representative of the stored energy level-to-battery chargings relationship from the module memory.

22. The charger of claim 20, wherein:

a load resistor is mounted to said base unit;

a switch is mounted to said base unit, said switch is configured to selectively connect the battery across said load resistor; and

said processor is further configured to selectively actuate said switch and to measure a voltage across said load resistor so that said said processor determines the stored energy of the battery by selectively connecting the battery across said load resistor;

measuring a voltage-at-load of the battery across said load resistor; and

determining the stored energy of the battery based on the measured voltage-at-load.

23. The charger of claim 20, wherein:

said display includes a light emitting element; and

said processor causes said display to indicate the results of the comparison of the stored energy in the battery to the minimum stored energy level by selectively actuating said light emitting element as a function of the results of the comparison.

24. A charger for providing energization current to a battery, the battery having a memory, said charger having:

a current source configured to be connected to the battery for supplying a charging current to the battery;

a energy-measuring circuit that is selectively connected to the battery for measuring the stored charge of the battery;

a display; and

a processor, said processor being connected to;

said current source;

said energy-measuring circuit;

the battery memory for reading data from and writing data to the battery memory; and

to said display, and said processor is configured to;

regulate the charging of the battery by said current source;

receive from said energy-measuring circuit an indication of the charge stored in the battery;

based on the number of times the battery has been charged based on the data read from the battery memory, determine a minimum stored energy level for the battery;

compare the stored charge in the battery to the minimum stored energy level;

actuate said display to indicate the results of said comparison; and

write into the battery memory new data that indicates the number of times the battery has been charged.

25. The charger of claim 24, further including a memory that contains data representative of a stored energy level-to-battery chargings relationship for the battery and said processor determines the minimum stored energy level for the battery by reading the data from the memory that contains the data representative the minimum stored energy level-to-battery chargings relationship.

26. The charger of claim 25, further including:

a module that is removably connected to said current source and said processor, said module having a socket adapted to receive the battery, conductors for establishing an electrical connection between said current source and said processor and the battery and a module memory wherein, said module memory contains the data representative of the minimum stored energy level-to-battery chargings relationship; and

wherein, said processor reads the data representative of the minimum stored energy level-to-battery chargings relationship from the module memory.

27. The charger of claim 24, wherein:

said energy-measuring circuit includes;

a load resistor and;

a switch, said switch being configured to selectively connect the battery across said load resistor; and

said processor is further configured to selectively actuate said switch and to measure a voltage across said load resistor so that said processor determines the stored charge of the battery by;

selectively connecting the battery across said load resistor;

measuring a voltage-at-load of the battery across said load resistor; and

determining the stored charge of the battery based on the measured voltage-at-load.

28. The charger of claim 24, wherein:

said display includes a light emitting element; and

said processor causes said display to indicate the results of the comparison of the stored energy in the battery to the minimum stored energy level by selectively actuating said light emitting element as a function of the results of said comparison.