Microprocessor controlled battery charger

• US 5,013,992 A
• Filed: 10/12/1988
• Issued: 05/07/1991
• Est. Priority Date: 10/12/1988
• Status: Expired due to Fees

• Current Assignee: Textron IPMP L.P
• Original Assignee: E-Z-Go Division of Textron
• Inventors: Eavenson, Jimmy N., Pugh, Donovan M.
• Primary Examiner(s): HICKEY, ROBERT
• Application Number:
  US07/256,779
• Time in Patent Office: 937 Days
• Field of Search: 320/20, 320/21, 320/32, 320/37, 320/38, 320/39, 320/40, 320/31
• US Class Current: 320/158
• CPC Class Codes: H02J 7/007184 in response to battery voltage gradient
• CPC Class Codes: Y10S 320/21 State of charge of battery

Abstract

A battery charger 10 includes a microprocessor device 12 coupled to a voltage to frequency converter 18 for determining a magnitude of a voltage potential appearing across a battery under charge. The microprocessor has an output for activating a source of battery charging power when the determined magnitude of the voltage is within a predetermined range of voltages. During a charge cycle the microprocessor maintains an elapsed time counter and determines if a battery reaches full charge within 30 minutes or does not reach a full charge after 16 hours. In either case the source is deactivated. The microprocessor also determines when a battery reaches a threshold voltage after which the rate of rise of the battery voltage is compared to a predetermined rate of rise. When the measured rate of rise is less than the predetermined rate of rise the microprocessor initiates a final charge cycle wherein the battery is charged for one additional hour. The battery charger includes a display 20 wherein the microprocessor displays the elapsed charge time or the measured battery voltage or a number of codes such as error codes. The battery charger further includes a backup timer 30 which deactivates the source of battery charging power after 16 hours.

Claims

1. A battery charger comprising:

means for providing electrical power for charging a battery to a predetermined voltage potential;

means, coupled to the battery, for determining a magnitude of a voltage potential across the battery; and

means, having a first input signal coupled to said determining means and a first output signal coupled to said power providing means, for controlling the operation of said power providing means for charging the battery, said controlling means being responsive to the determined magnitude of the voltage potential for activating said power providing means when the magnitude of the voltage potential is greater than a predetermined minimum voltage potential and less than a predetermined maximum voltage potential;

wherein

said controlling means is comprised of timer means for maintaining a time expressive of an interval of time that said power providing means is activated;

wherein

said controlling means is operable for deactivating said power providing means if the magnitude of the battery voltage potential exceeds a first reference voltage potential within a first predetermined interval of time; and

wherein

said first reference voltage potential is approximately 42.4 volts and wherein said first predetermined interval of time is approximately 30 minutes.

2. In a battery charger having at least two electrical terminals which are adapted for connection to a battery for coupling battery charging power to the battery, a method of charging a battery comprising the steps of:

measuring a voltage potential appearing across the two electrical terminals;

determining if the measured potential is within a range of acceptable voltage potentials;

if the potential is determined to be within the range of acceptable voltage potentials the method includes the steps of

activating a source of battery charging power;

initiating a timer for recording a total amount of time that the source of battery charging power is activated; and

in a repetitive manner

determining if the voltage potential appearing across the two electrical terminals exceeds a first or exceeds a second predetermined voltage potential;

determining if the recorded time exceeds a predetermined maximum charge time; and

if the determined voltage potential exceeds the second predetermined voltage potential the method includes the steps of;

determining if the recorded time is less than a predetermined minimum amount of time;

if the recorded time is determined to be less than the predetermined minimum amount of time the method includes the steps of

deactivating the source of battery charging power; and

displaying information to an operator;

if the recorded time is determined to be equal to or greater than the predetermined minimum amount of time the method includes a step of

determining if a rate of change of the voltage potential is less than a predetermined rate of change;

if the rate of change is determined to be less than the predetermined rate of change the method includes the steps of

initiating a final charge period wherein the source of battery charging power remains activated for a predetermined final period; and

deactivating the source of battery charging power after the predetermined final period.

3. In a battery charger having at least two electrical terminals which are adapted for connection to a battery for coupling battery charging power to the battery, a method of charging a battery comprising the steps of:

measuring a voltage potential appearing across the two electrical terminals;

determining if the measured potential is within a range of acceptable voltage potentials;

if the potential is determined to be within the range of acceptable voltage potentials the method includes the steps of

activating a source of battery charging power;

initiating a timer for recording a total amount of time that the source of battery charging power is activated; and

in a repetitive manner

determining if the voltage potential appearing across the two electrical terminals exceeds a first or exceeds a second predetermined voltage potential; and

determining if the recorded time exceeds a predetermined maximum charge time;

the method including a step of,

deactivating the source of battery charging power if the magnitude of the battery voltage potential is determined to exceed the first reference voltage potential within a first predetermined interval of time, indicating that the battery was in a fully charged or a substantially fully charged condition when a charging cycle was initiated, and

wherein said first reference voltage potential is approximately 42.4 volts and wherein said first predetermined interval of time is approximately 30 minutes.

4. A battery charger for charging a lead-acid battery, comprising:

means for electrically coupling terminals of a lead-acid battery to a source of battery charging power;

voltage measuring means having an input coupled to said electrical coupling means for measuring a voltage potential between the terminals of the battery; and

microprocessor means having a first input coupled to an output of said voltage measuring means for receiving the measured voltage potential therefrom, said microprocessor means further having a first output signal coupled to said source of battery charging power for controlling the activating and deactivating of said source;

said battery charger further comprising timer means having an input coupled to a second output signal of said microprocessor means, said timer means being activated by said microprocessor means for generating an output signal after a predetermined interval of time, said timer means output signal being coupled to said source of battery charging power for deactivating said source after the predetermined interval of time, said timer means further maintaining a time expressive of an interval of time that said source of battery charging power is activated; and

wherein

said battery charger further comprises means coupled to said microprocessor means and responsive thereto for deactivating said source of battery charging power if the magnitude of the voltage potential exceeds a reference voltage potential within a predetermined initial interval of time, indicating that the battery was in a fully charged or a substantially fully charged condition when a charging cycle was initiated, and

wherein said reference voltage potential is approximately 42.4 volts and wherein the predetermined initial interval of time is approximately 30 minutes.