Battery charging system

• US 4,433,277 A
• Filed: 06/21/1982
• Issued: 02/21/1984
• Est. Priority Date: 06/21/1982
• Status: Expired due to Term

• Current Assignee: Enid Hutchinson, Rockwell International Corporation
• Original Assignee: Rockwell International Corporation
• Inventors: Kalinsky, Wayne A., Carollo, James A.
• Primary Examiner(s): Shoop, William M.
• Assistant Examiner(s): Ault, Anita M.
• Application Number:
  US06/390,151
• Time in Patent Office: 610 Days
• Field of Search: 320/5, 320/6, 320/15, 320/20, 320/22, 320/23, 320/24, 320/30, 320/31, 320/32, 320/33, 320/34, 320/35, 320/36, 320/39, 320/40, 320/43, 320/45
• US Class Current: 320/149
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: Y10S 320/32 Voltage divider having diverse elements other than merely plural resistors

Abstract

A battery charger utilizes three basic modes of operation that includes a maintenance mode, a rapid charge mode and time controlled limited charging mode. The device utilizes feedback from the battery being charged of voltage, current and temperature to determine the mode of operation and the time period during which the battery is being charged.

Claims

1. A battery charger comprising:

means for providing a power source which delivers a charging signal to a battery;

means coupled to said means for providing a power source and responsive to a control signal for controlling the charging signal delivered to a battery to be one of a first charging signal, a second maintenance charging signal and a third charging signal;

first means for providing a first reference signal representative of a first predetermined charge level of a battery;

second means for providing a second reference signal which is variable in accordance with the temperature of a battery and is representative of a second predetermined charge level of a battery;

means for sensing the charge level of a battery and providing a charge level output signal;

means responsive to said charge level output signal and said first reference signal for providing a control signal to said means for controlling and causing it to deliver a first charging signal when said battery charge level is less than said first predetermined charge level and a second maintenance charging signal when said battery charge level is equal to or greater than said first predetermined charge level;

means responsive to said charge level output signal and said second reference signal for detecting when a battery charge level equals said second predetermined charge level and providing a control signal to said means for controlling and causing it to deliver a third charging signal for a predetermined charge period; and

means responsive to the termination of said predetermined charge period for providing a control signal to said means for controlling and cause it to deliver said second maintenance charging signal.

2. The battery charger of claim 1 further comprising means for current limiting said charging signal.

3. The battery charger of claim 1 further comprising means responsive to said charge level output signal for determining when that charge level output signal does not accurately reflect the actual charge level of a battery and means responsive to said actual charge level being equal to or greater than said first predetermined charge level for causing said means responsive to said charge level output signal and said first reference signal to provide a control signal to said means for controlling and cause it to deliver said second maintenance charging signal.

4. The battery charger of claim 1 further comprising means for sensing the number of batteries to be charged and coupled to extend said predetermined charge period to a multiple of that period equal to the number of batteries being charged.

5. The battery charger of claim 1 wherein said means for controlling comprises:

a first transistor having an emitter, collector, and base with said emitter being coupled to receive said charging signal and said collector being coupled to provide said charging signal to a battery;

a second transistor having a collector, emitter, and base, said second transistor collector being coupled to the base of said first transistor and the emitter of said second transistor being coupled to ground;

a first operational amplifier having first and second inputs and an output coupled to the base of said second transistor; and

a first voltage divider having first and second terminals and a third terminal for providing a variable voltage, said first terminal being coupled to receive said charge level output signal, said second terminal being coupled to ground, and said third terminal being coupled to the first input of said first operational amplifier, said second means being coupled to provide said second reference signal to the second input of said operational amplifier.

6. The battery charger of claim 5 further comprising means responsive to the charging signal at the output of said collector of the first transistor for controlling the base of said second transistor to current limit said charging signal.

7. The battery charger of claim 6 wherein said second means comprises a source of regulated voltage and a thermistor coupled to said regulated source for providing a variable voltage output as the temperature variable second reference signal, said thermistor being coupled in physical contact to sense the temperature of a battery.

8. The battery charger of claim 7 wherein said first means comprises a second voltage divider having a first terminal coupled to said regulated source, a second terminal coupled to ground, and a third terminal coupled to provide a voltage as said first reference signal.

9. The battery charger of claim 8 wherein said means responsive to said charge level output signal and said first reference signal and said means responsive to said charge level output signal and said second reference signal each include means for changing the impedance of said first voltage divider to change its variable voltage output.

10. The battery charger of claim 9 wherein said means responsive to said charge level output signal and said first reference signal includes a second operational amplifier having first and second inputs and an output, said first input of said second operational amplifier being coupled to said third terminal of the second voltage divider, said second input of said second operational amplifier being coupled to receive said charge level output signal and said output of said second operational amplifier coupled to said means for changing the impedance of said first voltage divider.