Method and apparatus for charging a nickel-cadmium battery

Claim 1

A method for charging a nickel-cadmium battery comprising the steps of: a. supplying a constant charging current to said battery; b. measuring the battery voltage, while said battery is receiving said charging current, at intervals not greater than 30 seconds; c. comparing the current measured voltage with the next previous measured voltage to determine the voltage change during the last interval; and, d. terminating said charging current when the individual voltage changes during two successive intervals each exceed a predetermined negative value.

Claim 2

A method for charging a nickel-cadmium battery comprising the steps of: a. supplying a constant charging current to said battery; b. measuring the battery voltage, while said battery is receiving said charging current, at intervals not greater than 30 seconds; c. comparing the current measured voltage with the next previous measured voltage to determine the voltage change during the last interval; and, d. terminating said charging current when the individual voltage changes during two successive intervals each exceed a predetermined negative value.

Claim 8

A method of charging a nickel-cadmium battery comprising the steps of: a. supplying a charging current to said battery; b. measuring said battery voltage while continuing to apply said charging current; c. storing said measured battery voltage; d. measuring said battery voltage after a predetermined interval while continuing to apply said charging current; e. comparing the stored battery voltage of step c with the measured battery voltage of step d; f. comparing the result of step e with a predetermined setpoint value if the comparison indicates that the voltage of step b is greater than the voltage of step d; g. storing an indicator if the result of the comparison of step f indicates that the result of step f is greater than said setpoint value, and erasing an indicator stored on the previous sequence if the comparison of step f indicates that the setpoint value has not been exceeded; h. repeating steps a through g until two successive comparisons of step f indicate that the result of step e is greater than said setpoint value; and, i. terminating said charging current when two successive comparisons of step f indicate that the result of step e is greater than said setpoint value.

Claim 9

A method of charging a nickel-cadmium battery comprising the steps of: a. supplying a charging current to said battery; b. measuring said battery voltage while continuing to apply said charging current; c. storing said measured battery voltage; d. measuring said battery voltage after a predetermined interval while continuing to apply said charging current; e. comparing the stored battery voltage of step c with the measured battery voltage of step d; f. comparing the result of step e with a predetermined setpoint value if the comparison indicates that the voltage of step b is greater than the voltage of step d; g. storing an indicator if the result of the comparison of step f indicates that the result of step f is greater than said setpoint value, and erasing an indicator stored on the previous sequence if the comparison of step f indicates that the setpoint value has not been exceeded; h. repeating steps a through g until two successive comparisons of step f indicate that the result of step e is greater than said setpoint value; and, i. terminating said charging current when two successive comparisons of step f indicate that the result of step e is greater than said setpoint value.

Claim 15

A method of charging a nickel-cadmium battery comprising the steps of: a. supplying a charging current to said battery; b. measuring the battery voltage while continuing to supply a charging current to said battery; c. measuring the battery voltage after a predetermined interval while continuing to supply a charging current to said battery; d. determining if the battery voltage has dropped more than a predetermined setpoint value during said predetermined interval; and, e. terminating said charging current when the battery voltage drops more than said setpoint value on two successive measurements.

Claim 16

A method of charging a nickel-cadmium battery comprising the steps of: a. supplying a charging current to said battery; b. measuring the battery voltage while continuing to supply a charging current to said battery; c. measuring the battery voltage after a predetermined interval while continuing to supply a charging current to said battery; d. determining if the battery voltage has dropped more than a predetermined setpoint value during said predetermined interval; and, e. terminating said charging current when the battery voltage drops more than said setpoint value on two successive measurements.

Claim 19

A method of charging a nickel-cadmium battery under the control of a microprocessor comprising the steps of: a. continuously supplying a constant charging current to said battery through a switch controlled in response to the signal at a first output port of said microprocessor; b. monitoring the battery voltage at intervals not greater than 30 seconds by connecting said battery to an analog to digital converter, while continuing to supply said charging current, through a switch controlled in response to the signal at a second output port of said microprocessor and transmitting the digital output of said analog to digital converter to an input port of said microprocessor; c. processing the digital values transmitted to said input port to determine when the monitored battery voltage drops more than a predetermined setpoint value during two successive intervals; and, d. developing a signal at said first output port to open said switch when the processing of step c indicates that the setpoint amount has been exceeded during two successive intervals.

Claim 20

A method of charging a nickel-cadmium battery under the control of a microprocessor comprising the steps of: a. continuously supplying a constant charging current to said battery through a switch controlled in response to the signal at a first output port of said microprocessor; b. monitoring the battery voltage at intervals not greater than 30 seconds by connecting said battery to an analog to digital converter, while continuing to supply said charging current, through a switch controlled in response to the signal at a second output port of said microprocessor and transmitting the digital output of said analog to digital converter to an input port of said microprocessor; c. processing the digital values transmitted to said input port to determine when the monitored battery voltage drops more than a predetermined setpoint value during two successive intervals; and, d. developing a signal at said first output port to open said switch when the processing of step c indicates that the setpoint amount has been exceeded during two successive intervals.

Claim 22

A system for charging a nickel cadmium battery comprising: a. a source of charging current; b. a charging current switch, operable in response to a control signal, for connecting said source of charging current to a battery; c. analog to digital converter means, connectable to said battery in response to a control signal for developing a digital output signal representative of the voltage of said battery while connected to said source of charging current; d. microprocessor control means, operating under program control, for developing said charging current switch control signal and said analog to digital converter control signal to connect said battery to said source of charging current and periodically simultaneously connect said analog to digital converter to said battery and transfer said digital output signal to said microprocessor; e. setpoint storage means in said microprocessor control means for storing a digital value representative of a predetermined voltage drop of said battery; f. said microprocessor program control including a sequence of program steps effective to cause said analog to digital converter to be periodically simultaneously connected to said battery and to compare the change from the previous digital output signal from said battery with said stored setpoint value and to store an indication when said setpoint is exceeded; and, g. said microprocessor program control further including a sequence of program steps effective to terminate said charging current switch control signal on the occurrence of an indication that the setpoint has been exceeded on two successive comparisons of the change in battery voltage to said setpoint value.

Claim 23

A system for charging a nickel cadmium battery comprising: a. a source of charging current; b. a charging current switch, operable in response to a control signal, for connecting said source of charging current to a battery; c. analog to digital converter means, connectable to said battery in response to a control signal for developing a digital output signal representative of the voltage of said battery while connected to said source of charging current; d. microprocessor control means, operating under program control, for developing said charging current switch control signal and said analog to digital converter control signal to connect said battery to said source of charging current and periodically simultaneously connect said analog to digital converter to said battery and transfer said digital output signal to said microprocessor; e. setpoint storage means in said microprocessor control means for storing a digital value representative of a predetermined voltage drop of said battery; f. said microprocessor program control including a sequence of program steps effective to cause said analog to digital converter to be periodically simultaneously connected to said battery and to compare the change from the previous digital output signal from said battery with said stored setpoint value and to store an indication when said setpoint is exceeded; and, g. said microprocessor program control further including a sequence of program steps effective to terminate said charging current switch control signal on the occurrence of an indication that the setpoint has been exceeded on two successive comparisons of the change in battery voltage to said setpoint value.