APPARATUS FOR CONTROLLING A PULSATING BATTERY CHARGER

• US 3,593,100 A
• Filed: 10/02/1969
• Issued: 07/13/1971
• Est. Priority Date: 10/02/1969
• Status: Expired due to Term

• Current Assignee: Foster George William
• Original Assignee: Foster George William
• Inventors: FOSTER GEORGE WILLIAM
• Application Number:
  US04/863,074
• Time in Patent Office: 649 Days
• US Class Current: 320/139
• CPC Class Codes: H02J 7/007182 in response to battery voltage

Abstract

An automatic battery charging circuit employing rectified alternating current includes a capacitor which is connected across the battery by a switching transistor only during the intervals between the pulses of charging current, and a level responsive transistor or trigger circuit, which responds when the voltage across the capacitor exceeds a predetermined value, and then cuts off or reduces the charging current. Thus the duration of the charge (or a phase of it) is determined by the battery voltage during the intervals between pulses of charging current, and is less dependent on battery resistance and temperature than conventional systems.

Claims

1. Apparatus for charging a battery from a pulsating supply having terminals for connection to the battery, comprising;

a charge control device connected between the supply terminals and said battery terminals for terminating the charging of said battery, a capacitor for sensing the voltage of said battery only during the intervals of said pulsating supply not charging said battery and for controlling said charge control device, and switching means driven by said pulsating supply and conducting only during the intervals between pulses of said supply charging said battery to charge said capacitor.

2. Charging apparatus as claimed in claim 1 in which said charge control device includes an impedance, said switching means comprises a transistor having its base-emitter circuit shunted across said impedance.

3. Charging apparatus as claimed in claim 2 in which said impedance includes a transistor which seRves to terminate the charging of said battery.

4. Charging apparatus as claimed in claim 2 in which the charging current is half-wave and said impedance further includes a diode serving to provide half-wave rectification of the output of said pulsating supply.

5. Charging apparatus as claimed in claim 1 in which said charge control device includes a level responsive trigger circuit responsive to the capacitor voltage to terminate the charging of the battery.

6. Charging apparatus as claimed in claim 1 in which said charge control device includes a current control device for reducing the charging current to said battery.

7. Charging apparatus as claimed in claim 6 in which said current control device is a single transistor to control the current and to terminate the charging of the battery.

8. Charging apparatus as claimed in claim 7 in which said current control device includes a resistor connected in series with said transistor and a Zener diode, and said current control device series to compare the drop of voltage across the resistor with that of said Zener diode and to control said transistor accordingly.