STORAGE BATTERY CHARGING APPARATUS

• US 3,848,173 A
• Filed: 11/08/1972
• Issued: 11/12/1974
• Est. Priority Date: 11/08/1972
• Status: Expired due to Term

• Current Assignee: Alfred Max Hase
• Original Assignee: Alfred Max Hase
• Inventors: Hase, Alfred Max
• Primary Examiner(s): Miller, J. D.
• Assistant Examiner(s): Hickey, Robert J.
• Application Number:
  US05/304,858
• Time in Patent Office: 734 Days
• Field of Search: 320/2,22-24,37,38,39,40,48,31-34 312/326-328,22,23
• US Class Current: 320/159
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: H02J 7/00714 in response to battery charging or discharging current
• CPC Class Codes: H02J 7/12 using magnetic devices having controllable degree of saturation, i.e. transductors
• CPC Class Codes: Y10S 320/19 Charger status, e.g. voltmeter
• CPC Class Codes: Y10S 320/21 State of charge of battery
• CPC Class Codes: Y10S 320/22 Line impedance, e.g. resistor
• CPC Class Codes: Y10S 320/24 Inductor

Abstract

A battery charging apparatus has a control circuit which controls the rate of input AC power through a synchronous switch - a saturable core reactor, magnetic amplifier or a pair of antiparallel silicon controlled rectifiers. The operation of the charger is initially constant current, but has a tapered, constant voltage transition to a continuous controlled trickle charge. A monitor and override circuit is timed, and initiates step-function transfers to lower constant current charging rates at various times throughout the charging program if the charging rate at the time of any such step function transfer is higher than the level to which the rate will be transferred. A status indication may be provided if a step transfer occurs.

Claims

1. In a storage battery charging apparatus which is adapted at its input for connection to a source of electrical energy, and at its output to the terminals of a storage battery;

said apparatus including controllable synchronous switch means adapted to control the rate of electrical energy input;

said apparatus having a multirate charging current output program, including a high charging rate at the beginning of the program, a controlled and tapered transition from high to low charging rate, and a continuous trickle charging rate at the end of the program until the battery is disconnected or the charging program terminated;

said high charging rate and said trickle charging rate each having a substantially constant current output;

the improvement comprising a control circuit and an override and timer circuit, where;

a. said control circuit includes means to initiate operation of a taper charge mode of operation of said battery charger apparatus when the terminal voltage of the battery reaches a predetermined level, said control circuit including means to drive said controllable synchronous switch so as to reduce the rate of electrical energy input by controlling the operating period of said synchronous switch, in order to maintain the output voltage of said battery charger apparatus constant at said predetermined level until such time as the controlled operation period of said synchronous switch reduces to a perdetermined minimum period, or until expiration of a predetermined amount of time from the beginning of the charging program as determined by said override and timer circuit; and

b. said override and timer circuit includes means for monitoring and overriding the control circuit, including i. a driven time-switch whose operation is initiated at the beginning of said charging program;

ii. first current control means made operable at the beginning of said charging program to maintain said output current at a first predetermined value;

iii. first override means made operable by said time-switch at a first predetermined time during said charging program to override said control circuit if the output current of said apparatus is higher than a second predetermined value which is lower than said first predetermined value, so as to reduce said output current to said second predetermined value; and

iv. second override means made operable by said time-switch to override said control circuit at a second predetermined time which is later than said first time during said charging program, to reduce said output current to said continuous trickle charging rate

2. The storage battery charger apparatus of claim 1 where said controllably synchronous switch means is an ampere-turns transductor having a control coil;

and where said means to drive said controllable synchronous switch includes a circuit parallel to said control coil of said ampere-turns transductor, including voltage reference sensing means and a transistor in series with a first resistor;

said voltage reference sensing means being connected to drive the base of said transistor when current flow occurs in said voltage reference sensing means so as to maintain the output voltage of said battery charger apparatus constant at said predetermined level until said voltage reference sensing means drives said transistor base substantially to full conduction so as to shunt said first resistor across said control coil.

3. The storage battery charger apparatus of claim 2 wherein said first current control means includes a second resistor in series with said control coil of said ampere-turns transductor across the terminals of said storage battery;

said first override means comprises switch mEans in series with a third resistor and arranged to close at said first predetermined time so as to shunt said third resistor across said control coil; and

said second override means includes switch means in series with said first resistor and arranged to close at said second predetermined time so as to shunt said first resistor across said control coil.

4. The storage battery charging apparatus of claim 2 including means on said time-switch to alter at least the second predetermined time of said charging program.

5. The storage battery charging apparatus of claim 2 including means to alter said control circuit so as to change the level of said predetermined battery terminal voltage at which said taper charge operation is initiated by said control circuit.

6. The storage battery charging apparatus of claim 2 including means to alter said first and second predetermined values of output current.

7. The storage battery charging apparatus of claim 2 including means to alter the predetermined value of said trickle charging rate of said output current.

8. The storage battery charging apparatus of claim 3 further including voltage sensing means across said first override means and said control coil to sense high current flow in said control coil, and signal means actuated by said voltage sensing means.

9. The storage battery charging apparatus of claim 8 further including voltage clamping means and amplifier means to maintain actuation of said signal means.