Timed battery charger

• US 5,248,928 A
• Filed: 03/19/1992
• Issued: 09/28/1993
• Est. Priority Date: 09/18/1990
• Status: Expired due to Fees

• Current Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Original Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Inventors: Gilmore, Alan A.
• Primary Examiner(s): Stephan, Steven L.
• Assistant Examiner(s): TSO, EDWARD H
• Application Number:
  US07/853,842
• Time in Patent Office: 558 Days
• Field of Search: 320/37, 320/38, 320/2, 320/27, 320/22, 320/23, 320/24, 320/21
• US Class Current: 320/142
• CPC Class Codes: H02J 7/0071 with a programmable schedule

Abstract

A charger 10 includes facility, such as a capacitor 14, for establishing a constant current source which is rectified by rectifier 16 to provide a supply of charging current at a single level in each of two successive periods of a charging cycle. The output of rectifier 16 is coupled through a SCR 26 to a battery B to be charged. Under control of a timer 28, SCR 26 remains conductive for a prescribed continuous period to facilitate the supply of the single-level charging current to battery B during a full charge or first period mode at a 100% duty cycle. At the end of the prescribed first period, a timer 36 then controls the on-off operation of SCR 26 to facilitate the supply of the single-level charging current during a trickle charge mode at a 20% duty cycle. In an alternative embodiment, a charge 100 includes four timers 118, 120, 122 and 124 which provide for three phases or modes of operation in which a single-level charging current is supplied to battery B at a duty cycle of 75% during a first of the three periods, at a duty cycle of 100% during a second of the three periods and at a duty cycle of 12.5% during a third of the three periods.

Claims

1. A timed battery charger for processing a battery through a charging cycle, which comprises:

a current source for providing current at a single predetermined level at all times during the charging cycle;

means for dividing the charging cycle into a plurality of prescribed timed periods during each of which the current at the single predetermined level is available to be supplied to the battery for charging of the battery;

means for establishing a prescribed duty cycle of operation for each of the plurality of prescribed timed periods; and

means for facilitating the supply of current from the current source at the single predetermined level in accordance with the duty cycle of operation for each of the plurality of prescribed timed periods.

2. The timed battery charger as set forth in claim 1, wherein the current source includes:

a capacitor connectable on one side thereof to an AC power source for developing a constant current source; and

a rectifier connected to the other side of the capacitor for rectifying the output of the capacitor to provide the current at the single predetermined level.

3. The timed battery charger as set forth in claim 1, wherein the dividing means includes at least one timer which establishes a first period at which the single level current is supplied to the battery and initiates at least a second period at which the single level current is supplied to the battery.

4. The timed battery charger as set forth in claim 1 wherein the establishing means includes a least one timer which is operable to establish the duty cycle of operation for each of the plurality of periods.

5. The timed battery charger as set forth in claim 1, wherein the facilitating means includes a switching element connected in a charging current path which is responsive to the establishing means to facilitate the supplying of the single-level current in accordance with the duty cycles of each of the periods.

6. The timed battery charger as set forth in claim 1, wherein the current source includes:

a transformer having a primary and a secondary with the primary being connectable to an AC input power source, and

a rectifier connected to the secondary of the transformer for rectifying the current at the secondary to provide the current at the single level.

7. The timed battery charger as set forth in claim 1, wherein the current source includes:

a capacitor connectable on one side thereof to an AC power source, and

a switching element connected in a current path which includes the capacitor and the battery;

and the timed battery charger further comprises;

means for allowing the capacitor to charge initially slowly notwithstanding operation of the switching element.

8. The timed battery charger as set forth in claim 1, which further comprises means for preventing the initiation of the operation of the facilitating means during any period when the instantaneous voltage level across the facilitating means is above a prescribed level.

9. The timed battery charger as set forth in claim 8, wherein the facilitating means includes a first switching element connected in a battery-charging current path and the preventing means includes a second switching element which prevents the first switching element from turning on when the instantaneous voltage level across the first switching element is above the prescribed level.

10. A timed battery charger for processing a battery through a charging cycle, which comprises:

a current source for providing current at a single predetermined level at all times during the charging cycle;

first controlling means for controlling the current source to supply current to the battery at the single level for a first prescribed charging period;

first duty cycle means for facilitating the supply of current to the battery at a first prescribed duty cycle during the first prescribed charging period;

second controlling means for controlling the current source to supply current to the battery at the single level for a second prescribed charging period;

second duty cycle means for facilitating the supply of current to the battery at a second prescribed duty cycle during the second prescribed charging period;

third controlling means for controlling the current source to supply current to the battery at the single level for a third prescribed charging period, and

third duty cycle means for facilitating the supply of current to the battery at a third prescribed duty cycle during the third prescribed charging period.

11. The timed battery charger as set forth in claim 10 wherein the current source includes a switch which is controlled by the first controlling means, the second controlling means and the third controlling means and through the first duty cycle means, the second duty cycle means and the third duty cycle means, respectively, to facilitate the supply of current at the single level to the battery.

12. The timed battery charger as set forth in claim 10 wherein each of the first prescribed charging period, the second prescribed charging period and the third prescribed charging period is a period different from either period of the remaining two periods.

13. The timed battery charger as set forth in claim 10 wherein each of the first prescribed duty cycle, the second prescribed duty cycle and the third prescribed duty cycle is a duty cycle different from either period of the remaining two duty cycles.

14. A timed battery charger for processing a battery through a charging cycle, which comprises:

means for supplying a charging current at a single level to the battery to be charged;

a first timer for establishing a first charging period during which the charging current at the single level is supplied by the supplying means;

a second timer for controlling operation of the supplying means at a first duty cycle during the first charging period so that the charging current is supplied to the battery at the single level and at the first duty cycle;

a third timer for establishing a second charging period and for controlling operation of the supplying means at a second duty cycle during the second charging period so that the charging current is supplied to the battery at the single level and at the second duty cycle, and

a fourth timer for controlling operation of the supplying means at a third duty cycle during a third charging period following completion of the second charging period whereby charging current at the single level is supplied to the battery at the third duty cycle.

15. The timed battery charger as set forth in claim 14 wherein:

operation of the first timer, the second timer and the third timer are initiated simultaneously;

the second timer is controlled to cease operation upon completion of first charging period, and

the fourth timer is controlled to initiate operation upon completion of the second charging period.

16. The timed battery charger as set forth in claim 14 wherein the supplying means includes a switch which is controlled during the first charging period, the second charging period and the third charging period to supply the charging current at the single level and at the first duty cycle, the second duty cycle and the third duty cycle, respectively.

17. The timed battery charger as set forth in claim 14 wherein the supplying means includes:

a rectifier, and

a transformer having a primary connectable to an AC input source and a secondary connected to the rectifier, the output of which provides the charging current at the single level.