Solid state battery charger

• US 6,218,812 B1
• Filed: 05/15/2000
• Issued: 04/17/2001
• Est. Priority Date: 05/17/1999
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Hanson, Mark E.
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US09/570,897
• Time in Patent Office: 337 Days
• Field of Search: 320/124, 320/125, 320/137, 320/156, 320/161
• US Class Current: 320/161
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A method for charging batteries using a solid state battery charger is disclosed which includes the steps of supplying a constant current to the batteries being charged until the battery voltage reaches a first threshold voltage value, supplying a constant voltage to the batteries being charged until current being drawn by the batteries reaches a threshold current value and supplying a constant current to the batteries being charged until a voltage rise per unit time threshold is met.

Claims

1. A method for charging batteries using a solid state battery charger, said method comprising the steps of:

supplying a constant current to the batteries being charged until the battery voltage reaches a first threshold voltage value; and

supplying a constant voltage to the batteries being charged until current being drawn by the batteries reaches a threshold current value.

2. A method according to claim 1 further comprising the step of supplying a constant current to the batteries being charged until a voltage rise per unit time threshold (dv/dt) is met.

3. A method according to claim 1 further comprising the step of continuously monitoring battery voltage.

4. A method according to claim 3 wherein when the battery voltage decreases to a second threshold voltage value said method further comprises the steps of:

supplying a constant current to the batteries being charged until the battery voltage reaches a first threshold voltage value;

supplying a constant voltage to the batteries being charged until current being drawn by the batteries reaches a threshold current value; and

supplying a constant current to the batteries being charged until a voltage rise per unit time threshold (dv/dt) is met.

5. A method according to claim 1 further comprising the step of inhibiting use of a device powered by the batteries during a charge cycle.

6. A method according to claim 1 further comprising the step of storing a running total of ampere-hours supplied by the battery charger.

7. A method according to claim 1 further comprising the step of storing a running total of a number of times each battery has dropped below a predetermined voltage value.

8. A method according to claim 1 further comprising the step of limiting a charge cycle to a predetermined time.

9. A method according to claim 1 further comprising the step of supplying a signal that indicates the charger is in a charge cycle.

10. A method according to claim 1 further comprising the step of supplying a signal that indicates a charge cycle is complete.

11. A method according to claim 1 further comprising the step of supplying a signal that indicates an 80% battery charge level during a charge cycle.

12. A method according to claim 1 further comprising the step of supplying a signal that indicates an over temperature condition in the battery charger.

13. A solid state battery charger comprising:

an output circuit for supplying current and voltage to a battery to be charged;

voltage and current measurement circuits for monitoring battery parameters;

a microprocessor; and

a memory, said memory to be either internal or external to said microprocessor, said microprocessor configured to apply a constant current charge to the batteries being charged until the battery voltage reaches a first threshold voltage value and supply a constant voltage to the batteries being charged until current being drawn by the batteries reaches a threshold current value.

14. A battery charger according to claim 13 wherein said microprocessor further configured to supply a constant current charge to the batteries being charged until a voltage rise per unit time threshold (dv/dt) is met.

15. A battery charger according to claim 14 wherein said voltage rise per unit time threshold (dv/dt) is less than 0.1 volts per cell per hour.

16. A battery charger according to claim 13 wherein said microprocessor further configured to continuously monitor battery voltage.

17. A battery charger according to claim 16 wherein when the battery voltage decreases to a second threshold voltage value said microprocessor further configured to:

supply a constant current to the batteries being charged until the battery voltage reaches a first threshold voltage value;

supply a constant voltage to the batteries being charged until current being drawn by the batteries reaches a threshold current value; and

supply a constant current to the batteries being charged until a voltage rise per unit time threshold (dv/dt) is met.

18. A battery charger according to claim 13 wherein said microprocessor further configured to inhibit use of a device powered by the batteries during a charge cycle.

19. A battery charger according to claim 13 wherein said microprocessor further configured to store a running total of ampere-hours supplied by the battery charger.

20. A battery charger according to claim 13 wherein said microprocessor further configured to store a running total of a number of times a battery or batteries has dropped below a predetermined voltage value.

21. A battery charger according to claim 13 wherein said microprocessor further configured to limit a battery charge cycle to a predetermined time.

22. A battery charger according to claim 13 wherein said microprocessor further configured to supply a signal that indicates the charger is in a charge cycle.

23. A battery charger according to claim 13 wherein said microprocessor further configured to supply a signal that indicates a charge cycle is complete.

24. A battery charger according to claim 13 wherein said microprocessor further configured to supply a signal that indicates an 80% battery charge level during a charge cycle.

25. A battery charger according to claim 13 wherein said microprocessor further configured to supply a signal that indicates an over temperature condition in the battery charger.

26. A battery charger according to claim 13 further comprising an interface for communicating battery and battery charger parameters to an external computer.

27. A battery charger according to claim 26 wherein said interface is infrared.

28. A battery charger according to claim 26 wherein said interface is a serial data interface.

29. A battery charger according to claim 22 wherein said battery charging algorithm further configured to communicate, battery charging voltage, battery charging current, battery charger temperature, total ampere-hours used, a number of times a battery voltage has dropped below a particular voltage threshold, initial battery charge state, error diagnostic messages, battery charge time, and user specified messages over said interface.