Device for charging accumulators

• US 4,217,533 A
• Filed: 03/08/1978
• Issued: 08/12/1980
• Est. Priority Date: 03/08/1977
• Status: Expired due to Term

• Current Assignee: Dirk A Van Beek
• Original Assignee: Dirk A Van Beek
• Inventors: Van Beek, Dirk A.
• Primary Examiner(s): Hickey, Robert J.
• Application Number:
  US05/884,590
• Time in Patent Office: 888 Days
• Field of Search: 320/20, 320/22-24, 320/32, 320/43, 320/39, 320/48, 320/57, 320/59
• US Class Current: 320/160
• CPC Class Codes: H02J 7/00718 in response to charge current gradient
• CPC Class Codes: H02J 7/007186 obtained with the battery disconnected from the charge or discharge circuit
• CPC Class Codes: Y10S 320/17 Sensing of "gassing" voltage
• CPC Class Codes: Y10S 320/19 Charger status, e.g. voltmeter

Abstract

A device for charging accumulators or batteries provides a substantially constant charging current for a first charging interval until a voltage level which is less than that of a fully charged accumulator is reached. At this time, the device continues charging in a sequence of subsequent time intervals with charging currents which decrease at different rates in each interval until the accumulator is fully charged. The duration of each of the subsequent time intervals and the rates at which the charging currents decrease may be adjusted to shorten charging time while minimizing gasification of water in the accumulator. The device can also be used to maintain the accumulator charged at a given float voltage.

Claims

1. A device for charging accumulators comprising;

input means for removable conductive connection to an accumulator to be charged for sensing the terminal voltage thereof;

initial charging means conductively connected to said input means to supply a substantially constant dc-charging current to the accumulator in response to the initially sensed terminal voltage during a first charging interval until a predetermined voltage level is attained as the sensed terminal voltage such predetermined voltage level being substantially lower than a voltage level for said accumulator when fully charged;

sequential charging means conductively connected to said input means for further charging said accumulator in a predetermined number of subsequent different time intervals subsequent to said first charging interval with differently decreasing dc-charging currents in each time interval, respectively, and said sequential charging means including means for mutually independently setting both each time interval and the decreasing rate of each decreasing dc-charging current to permit a minimum gasification of water from the accumulator and a minimum duration charging time.

2. A device as claimed in claim 1 wherein said input means comprises:

switching means for automatically switching on the initial constant dc-charging current from said initial charging means when the sensed terminal voltage thereof is below a predetermined voltage level.

3. A device as claimed in claim 1 or 2 wherein said input means further comprises:

switching means for switching off the final decreasing charging current to the accumulator in a last time interval of the subsequent time intervals of said sequential charging means when said sensed terminal voltage thereof has attained a predetermined value indicating that the accumulator is fully charged.

4. A device as claimed in claim 3 further comprising:

float charging means to supply a substantially constant float voltage to the charged accumulator after switching off the final decreasing charge current by said switching means.

5. A device as claimed in claims 1 or 2 wherein said charging means comprise:

a voltage-controlled current source, the output of which can be connected to one terminal of the accumulator;

a voltage follower, the input of which is formed by said one terminal of the accumulator;

a voltage divider connected to the output of said voltage follower;

the other terminal of said voltage follower connected to the other terminal of the accumulator;

a plurality of operational amplifiers which are fed back at their inverting inputs;

the non-inverting inputs of said plurality of operational amplifiers being connected to their respective tappings of said voltage divider;

a common reference voltage source;

a resistor connecting the inverting inputs of said plurality of operational amplifiers to said voltage source;

an operational amplifier fed back at its non-inverting input, and having said non-inverting input connected to a corresponding tapping of and having said voltage divider and its inverting input directly connected to said common reference voltage source; and

a number of series networks corresponding in number to said plurality of operational amplifiers, each of which networks includes a rectifier and a resistor, one terminal of each of which is connected to the output of one of said plurality of operational amplifiers and the other terminal of each of which is connected to the input of said voltage-controlled current source.

6. A device as claimed in claim 5, further including:

a series of network of;

a rectifier, one terminal of which is connected to the output of one of said plurality of operational amplifiers fed back at it inverting input;

the other terminal of said rectifier being connected to the junction of one of said rectifiers and said resistors of said series network.

7. A device as claimed in claim 1 further comprising:

indication means to visibly distinguishably indicate the mode of operation of said device.

8. A device as claimed in claim 7, wherein said indication means comprises:

a plurality of LED'"'"'s corresponding in number to the first interval and the number of subsequent time intervals, said LED'"'"'s being initially illuminated and during the progression of said charging intervals successively extinguishing to indicate the progress of charging by the device.