Battery management system

• US 5,225,762 A
• Filed: 04/29/1991
• Issued: 07/06/1993
• Est. Priority Date: 04/30/1990
• Status: Expired due to Term

• Current Assignee: George Langford
• Original Assignee: George Langford
• Inventors: Langford, George
• Primary Examiner(s): Stephan, Steven L.
• Assistant Examiner(s): KINCAID, KRISTINE LYNN
• Application Number:
  US07/692,385
• Time in Patent Office: 799 Days
• Field of Search: 320/14, 320/20, 320/21, 320/39, 320/40, 320/5, 320/37, 320/38
• US Class Current: 320/129
• CPC Class Codes: H02J 7/00711 with introduction of pulses during the charging process
• CPC Class Codes: Y10S 320/13 Fault detection

Abstract

A battery charger providing a fast charge while the output voltage of the battery does not exceed a reference voltage. The battery charger providing a self-discharge interval after the output voltage exceeds the predetermined reference voltage.

Claims

1. A method of charging a battery comprising the steps of:

applying to the battery a first current of sufficient amplitude to provide a fast charge while the output voltage of the battery does not exceed a first predetermined reference voltage;

terminating the first current a first predetermined interval after the output voltage exceeds the first predetermined reference voltage;

allowing the battery to self-discharge while the output voltage exceeds the first predetermined reference voltage, thereby defining a self-discharge interval;

repeating the preceding steps while the self-discharge interval is less than a first predetermined multiple of the first predetermined interval so as to generate first current pulses;

applying a load to the battery when the self-discharge interval exceeds a second predetermined multiple of the first predetermined interval, said second predetermined multiple being less than said first predetermined multiple, said load being insufficient to substantially discharge the battery; and

rejecting the battery if the output voltage under said load differs by a predetermined amount from the output voltage under no load.

2. A method as recited in claim 1, further including the steps of:

measuring the battery temperature; and

reducing the first predetermined reference voltage in proportion to an increase in the battery temperature.

3. A method as recited in claim 1, further including the initial steps of:

comparing the output voltage of the battery with a predetermined acceptance reference voltage after a predetermined test interval from initial application of said first current; and

rejecting the battery if the output voltage does not exceed the predetermined acceptance reference voltage.

4. A method as recited in claim 2, further including the initial steps of:

comparing the output voltage of the battery with a predetermined acceptance reference voltage after a predetermined test interval from initial application of said first current; and

rejecting the battery if the output voltage does not exceed the predetermined acceptance reference voltage.

5. A method as recited in claim 1, wherein said first predetermined multiple corresponds to a duty cycle of said first current pulses of about 10 percent.

6. A method as recited in claim 1, wherein said second predetermined multiple corresponds to a duty cycle of said first current pulses of about 50 percent.

7. A method as recited in claim 1, further including the step of:

applying to the battery a current of sufficient amplitude to provide a trickle charge.

8. An apparatus for charging a battery, comprising:

first charging means for charging the battery with a first current of sufficient amplitude to provide a fast charge;

a first comparator for comparing the output voltage of the battery with a first predetermined reference voltage;

first control means responsive to the first comparator for inhibiting the first charging means a first predetermined interval after the output voltage of the battery exceeds the first predetermined reference voltage;

said first control means further responsive to said first comparator for activating said first charging means when said output voltage falls below said predetermined reference voltage, a time between said inhibition and said activation being denoted as a battery self-discharge interval;

second control means for inhibiting the first charging means when said self-discharge interval exceeds a first predetermined multiple of the first predetermined interval and for producing an indication of completion of charging;

means for applying a load to the battery when the self-discharge interval exceeds a second predetermined multiple of the first predetermined interval, said second predetermined multiple being less than the first predetermined multiple, said load being insufficient to substantially discharge the battery; and

third control means responsive to the difference between the output voltage of the battery under the application of said load with the output voltage under the application of no load for inhibiting the first charging means if the difference exceeds a predetermined amount and for providing an indication of rejection of the battery.

9. An apparatus as recited in claim 8, further comprising:

a second comparator to compare the output voltage of the battery with a predetermined acceptance reference voltage after a predetermined test interval from said initial application of said first current; and

means responsive to said second comparator for inhibiting said first charging means if said output voltage does not exceed said acceptance reference voltage, and for providing an indication of rejection of the battery.

10. An apparatus as recited in claim 8, wherein said first predetermined multiple corresponds to a duty cycle of said first current pulses of about 10 percent.

11. An apparatus as recited in claim 8, wherein said second predetermined multiple corresponds to a duty cycle of said first current pulses of about 50 percent.

12. An apparatus as recited in claim 8, further comprising:

trickle charging means for charging the battery with a current of sufficient amplitude to provide a trickle charge.