Battery charging system and method of using same

• US 5,349,281 A
• Filed: 09/28/1992
• Issued: 09/20/1994
• Est. Priority Date: 03/22/1991
• Status: Expired due to Fees

• Current Assignee: HM Electronics Incorporated
• Original Assignee: HM Electronics Incorporated
• Inventors: Bugaj, Julian J.
• Primary Examiner(s): KINCAID, KRISTINE LYNN
• Application Number:
  US07/952,304
• Time in Patent Office: 722 Days
• Field of Search: 320/5, 320/6, 320/14, 320/15, 320/20, 320/21, 320/22, 320/23, 320/24, 320/31, 320/32, 320/37, 320/38, 320/39, 320/40
• US Class Current: 320/160
• CPC Class Codes: H02J 7/00038 using passive battery identification means, e.g. resistors or capacitors identification by mechanical connections H02J7/0045
• CPC Class Codes: H02J 7/00047 with provisions for charging different types of batteries
• CPC Class Codes: H02J 7/007184 in response to battery voltage gradient

Abstract

A battery charging system which prevents false switching from a fast charge mode to a trickle charge mode due to low frequency voltage aberration signals. The battery charging system includes a battery voltage analyzer and a plurality of battery charging and conditioning units for charging different types and kinds of nickel cadmium batteries. Firmware in the microprocessor rejects low frequency aberrations permitting a desired voltage signal to be produced which is indicative of the actual battery potential for charge switching purposes.

Claims

1. A method of conditioning a battery, comprising:

applying a high discharge current to the battery;

generating a conditioned signal continuously;

converting said conditioned signal into a digital signal indicative of a present potential value of the battery;

responding to said digital value by calculating periodically a derived battery potential value indicative of an averaged present potential value of the battery;

determining whether said averaged present potential value is a predetermined discharged battery potential value;

applying a high charge current to the battery when said averaged present potential value is substantially equal to said predetermined discharged battery potential value;

determining whether said averaged present potential value is a peak potential value;

storing said derived battery potential value when said averaged present potential value is the peak potential value;

responding to said digital signal by calculating periodically an incremental derived battery potential value relative to the stored peak potential value;

determining whether said incremental derived battery potential value is greater than or equal to a predetermined incremental battery potential value;

starting a timer in response to said incremental derived battery potential value being greater than or equal to said predetermined incremental battery potential value;

repeating said steps of generating, converting, responding, determining, applying, determining, storing, responding and determining;

resetting said timer if said derived battery potential value is the peak potential value;

resetting said timer in response to said incremental derived potential value having a potential value less than said predetermined incremental battery potential value; and

switching from applying said high charge current to the battery to applying a trickle charge current when said timer completes a predetermined counting sequence.

2. A method of conditioning a battery according to claim 1, further comprising:

determining whether the battery has been charged to a predetermined charged potential value within a predetermined period of time; and

generating a battery fault signal if the battery is not charged to said predetermined charged potential value within said predetermined time.

3. A method of analyzing a battery, comprising:

inserting the battery into a battery charger adapter coupled to a battery charger for enabling a charging current to be applied to the battery, said battery charger having fast charge means for applying a fast charge current to the battery and slow charge means for applying a trickle charge current to the battery, conditioning means coupled to the battery for generating a digital signal indicative of a present potential value of the battery, processor means responsive to said conditioning means for calculating periodically a derived battery potential value indicative of an averaged potential value of the battery, said processor means including means for calculating periodically an incremental derived potential value relative to a derived peak potential value of the battery and timing means for causing the charging current to be decreased from said fast charge current to said trickle charge current after a predetermined period of time during which said incremental derived potential value does not become less than a predetermined incremental value;

discharging the battery until said derived battery potential value is substantially equal to a predetermined discharged potential value;

charging the battery until said derived battery potential value is substantially equal to a predetermined charged potential value;

discharging the battery until said derived battery potential value is substantially equal to another predetermined discharged potential value;

charging the battery until said derived battery potential value is substantially equal to another predetermined charged potential value;

discharging the battery until said derived battery potential value is substantially equal to a predetermined final discharged potential value;

charging the battery until said derived potential value is substantially equal to a predetermined final charged potential value; and

applying a trickle charging current to the battery until it is removed from said battery charger adapter.

4. A method of analyzing a battery according to claim 3, wherein the last mentioned charging step includes:

determining whether said derived battery potential value is a peak battery potential value V_p ;

determining whether said derived battery potential value has decreased from said peak battery potential value V_p by a predetermined potential drop Δ

V.

5. A method of analyzing a battery according to claim 4, wherein said predetermined potential drop Δ

V is between about 22 millivolts per cell and about 18 millivolts per cell.

6. A method according to claim 5, wherein a more preferred predetermined potential drop Δ

V is between about 21 millivolts per cell and about 19 millivolts per cell.

7. A method according to claim 6, wherein a most preferred predetermined potential drop Δ

V is about 20 millivolts per cell.

8. A method of analyzing a battery according to claim 4, further comprising:

verifying for said predetermined period of time T that said derived battery potential value has decreased from said peak battery potential value to said predetermined potential drop Δ

V.

9. A method of analyzing a battery according to claim 8, wherein said predetermined period of time T is between about 1 minute and about 15 minutes.

10. A method of analyzing a battery according to claim 9 wherein a more preferred predetermined period of time T is between about 3 minutes and about 10 minutes.

11. A method of analyzing a battery according to claim 10 wherein the most preferred predetermined period of time T is about 5 minutes.

12. A method according to claim 3, further comprising:

generating a signal indicative that the battery is fully charged.

13. A method according to claim 3, wherein said first mentioned predetermined discharged potential value is between about 1.0 volts per cell and about 1.4 volts per cell.

14. A method according to claim 13, wherein a more preferred said first mentioned predetermined discharged potential value is between about 1.1 volts per cell and about 1.3 volts per cell.

15. A method according to claim 14, wherein a most preferred said first mentioned predetermined discharged potential value is about 1.2 volts per cell.

16. A method according to claim 15, wherein said predetermined discharged potential value, said another predetermined discharged potential value, and said predetermined final discharged potential value are substantially the same potential value.

17. A method according to claim 3, wherein said first mentioned predetermined charged potential value is between about 1.2 volts per cell and about 0.8 volts per cell.

18. A method according to claim 17, wherein a more preferred said first mentioned predetermined charged potential value is between about 1.1 volts per cell and about 0.9 volts per cell.

19. A method according to claim 18, wherein the most preferred said first mentioned predetermined charged potential value is about 1.0 volts per cell.

20. A method according to claim 19, wherein said predetermined charged potential value, said another predetermined charged potential value and said predetermined final charged potential value are substantially the same potential value.