US 3,944,904 AGranted

Battery charging circuit

OwnerAlfred M. Haseinventor

Life of this patent

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Abstract

A battery charging circuit is provided where a synchronous switch, such as a magnetic amplifier, saturable reactor, silicon controlled rectifier, triac or contactor, each of which is controllable, is inserted in a charging circuit and is controlled by a circuit such that when the terminal voltage of a battery which is being charged by a substantially constant, ripple-free DC current reaches a predetermined level, an intermittent DC charge is initiated. The periods of operation are of a predetermined, fixed length and at a predetermined current level. Means may be provided to reduce the finish charge to an intermittent trickle charge when the terminal voltage of the battery reaches its rated level. Counting means can be provided for determining the number of periods of operation of intermittent charging current delivered to the battery, for surveillance of battery condition and so as to determine ampere-hour back charge. The control circuit is arranged so as to be fail safe, by insertion of a current level bias control element in series in the control circuit for the synchronous switch, with the knowledge that such bias control elements fail "open". Thus, no override protection devices are required. The method of charging the battery includes supplying a constant, substantially ripple-free DC charging current until the battery terminal voltage reaches a predetermined level, and then initiating an intermittent DC charging current while continuously sensing the battery terminal voltage.

Claims7

Dependent claims

A battery charging circuit for charging storage batteries, including;

Dc circuit means for supplying an initial constant DC charging current to a battery from an alternating current source;
first and second adjustable battery terminal voltage sensing means;
control circuit means connected with said first battery terminal voltage sensing means and said DC circuit means for initiating an intermittent DC charging current supply to said battery, the first operating period of which is initiated at the instant when said battery terminal voltage reaches a first predetermined level;
synchronous switch means connected in the alternating current source side of said DC circuit means;
gate means connected to said first and second battery terminal voltage sensing means and to said synchronous switch means, said gate means being adapted to control said synchronous switch means so as to initiate and stop the supply of alternating current to the DC circuit means and thereby to control each operating period of time of said intermittent DC charging current supply;
and
a timing circuit which is connected to said gate means so as to control the length of each operating period of time including the first operating period of time, of said DC circuit means after said intermittent DC charging current supply has been initiated;
said second battery terminal voltage sensing means being connected to said gate means and adapted to operate after the first operating period of time of said DC circuit means;
said second voltage sensing means being set to initiate an operating period of said intermittent DC charging current supply each time the battery terminal voltage reaches a second predetermined battery terminal voltage level which is below said first predetermined voltage level.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 05/575,125Filed 7 May 1975 · continuation in part
Priority: 24 Sep 1973
Granted: 16 Mar 1976
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H02J 7/96
Regulation of charging or discharging current or voltage: in response to battery voltage
Y10S 320/24
Line impedance, e.g. resistor: inductor
Y10S 320/28
Electricity: battery or capacitor charging or discharging: regulating transformer, e.g. high leakage, ferro-resonant
H02J
Power supply and charging