Alkaline battery charger and method of operating same

• US 5,523,667 A
• Filed: 02/28/1994
• Issued: 06/04/1996
• Est. Priority Date: 01/27/1992
• Status: Expired due to Fees

• Current Assignee: PowerGenix Systems Inc (EnSite Power, Inc.)
• Original Assignee: Robert S. Feldstein
• Inventors: Feldstein, Robert S.
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): TSO, EDWARD H
• Application Number:
  US08/202,832
• Time in Patent Office: 827 Days
• Field of Search: 320/5, 320/6, 320/9, 320/14, 320/15, 320/18, 320/19, 320/21, 320/22, 320/39, 320/31, 320/37, 320/3
• US Class Current: 320/118
• CPC Class Codes: H02J 7/0018 using separate charge circuits

Abstract

Apparatus and methods for recharging various types of battery cells are enclosed involving alternating periods of charging and discharging of the cells, a reference charge cut-off voltage, a comparator for comparing cell voltage with cut-off voltage, and a circuit for stopping charging activity when cell open circuit voltage is at least a desired minimum voltage. Charge activity is terminated following the achievement of a minimum acceptable state-of-charge so as to limit the total current delivered to the cell in order to prevent cell degradation.

Claims

1. A battery charger, comprising:

means for charging each of one or more cells with a charge pattern which includes a time period of individual charge alternating with one or more time periods of individual discharge;

means for providing a charge cut-off voltage which represents a value sufficiently above a desired cell open circuit voltage to insure adequate charge acceptance, but sufficiently low to avoid significant cell degradation;

means for comparing the cell voltage of each of said one or more cells being charged to said cut-off voltage at the end of each time period of charge;

means for stopping said charge of said one or more cells individually whenever said voltage of said one or more individual cells being charged exceeds said cut-off voltage;

means for stopping said charge pattern of said one or more cells individually when said one or more individual cells being charged discharges above said cut-off voltage for a longer period of time as compared to the duration of the individual charge period;

means for stopping said charge pattern of said one or more cells individually when said cell voltage of said one or more individual cells being charged averages about said cut-off voltage for a longer period of time as compared to the duration of said time period of individual charge; and

means for restarting said charge pattern of said one or more cells after a long pulse time period.

2. The battery charger of claim 1 wherein:

said average value of said cell voltage is taken over a time period substantially longer than the duration of said time period of charge; and

said long pulse time period is substantially greater than the duration of said time period of said average value of said cell voltage.

3. The battery charger of claim 1 wherein said cell is selected from the group consisting essentially of zinc-manganese dioxide alkaline cells, zinc-manganese dioxide cells, rechargeable alkaline manganese cells, nickel cadmium cells, and standard and heavy duty dry cells.

4. The battery charger of claim 1 wherein said cut-off voltage is between 1.6 and 1.67 volts.

5. The battery charger of claim 4 wherein said cut-off voltage is 1.605 volts.

6. The battery charger of claim 5 wherein said means for charging applies a charging voltage of between 1.6 to 1.7 volts.

7. The method of charging one or more cells, comprising the steps of:

charging each of said one more cells with a charge pattern which includes a time period of individual charge alternating with one or more time periods of individual discharge;

setting a charge cut-off voltage which represents a value sufficiently high to insure adequate charge acceptance, but sufficiently low to avoid significant cell degradation;

comparing the voltage of each of said one or more cells being charged to said cut-off voltage at the end of each time period of charge;

stopping said charge of said one or more cells individually whenever said voltage of said one or more cells individually being charged exceeds said cut-off voltage;

means for stopping said charge pattern of said one or more cells individually when said cell voltage of said one or more individual cells being charged averages about said cut-off voltage for a longer period of time as compared to the duration of said time period of individual charge; and

restarting said charge pattern of said one or more cells after a long pulse time period.

8. The method of claim 7 wherein:

said average value of said cell voltage is taken over a time period substantially longer than the duration of said time period of charge; and

said long pulse time period is substantially greater than the duration of said time period of said average value of said cell voltage.

9. The method of claim 8 including the step of selecting said cell from the group consisting essentially of zinc-manganese dioxide alkaline cells, zinc-manganese dioxide cells, rechargeable alkaline manganese cells, nickel cadmium cells, and standard and heavy duty dry cells.

10. The method of claim 7 wherein said cut-off voltage is between 1.6 and 1.67 volts.

11. The method of claim 8 wherein said cut-off voltage is 1.605 volts.

12. The method of claim 11 wherein said step of charging applies a charging voltage of between 1.6 to 1.7 volts.