Apparatus and method for charging batteries

An apparatus for charging a battery of the type having a voltage characteristic associated therewith that varies with the state of charge of the battery and in which the variation of the characteristic with time during charging exhibits an inflection point prior to the battery attaining substantial full charge, the inflection point characterized by a change in the slope of the voltage characteristic from successive increases in slope to a decrease, said apparatus comprising:

• means for supplying electrical energy to the battery for charging thereof;
• and
• means connected to said supply means for monitoring said voltage characteristic during charging and computing the slope of the variation of said monitored voltage characteristic with time, for storing the maximum value of the so-computed slope values and comparing each successively computed slope value with said stored maximum value to identify the inflection point exhibited in the variation of the voltage characteristic prior to the battery attaining substantial full charge by identifying a change in the so-compared slope values from successive increases in slope to a decrease, and for controlling said supply means on the basis of the so-determined occurrence.

An apparatus for charging a battery of the type having a current characteristic associated therewith that varies with the state of charge of the battery and in which the variation of the current characteristic with time during charging exhibits an inflection point prior to the battery attaining substantial full charge, the inflection point characterized by a change in slope of the current characteristic from successive decreases to an increase, said apparatus comprising:

• means for supplying electrical energy to the battery for charging thereof;
• and
• means connected to said supply means for monitoring said current characteristic during charging and computing the slope of the variation of said monitored current characteristic with time, for storing the minimum value of the so-computed slope values, and comparing each successively computed slope value with said stored minimum value to identify the inflection point exhibited in the variation of the current characteristic prior to the battery attaining substantial full charge by identifying a change in the so-compared slope values from successive decreases in slope to an increase, and for controlling said supply means on the basis of the so-determined occurrence.

An apparatus for charging a battery of the type having a characteristic associated therewith that varies with the state of charge of the battery and in which the variation of the characteristic with time during charging exhibits an inflection point prior to the battery attaining substantial full charge and another inflection point that precedes the first-mentioned inflection point, each inflection point characterized by a change in sign of the second derivative of the variation of the characteristic with time, said apparatus comprising:

• means for supplying electrical energy to the battery for charging thereof;
• and
• means connected to said supply means for monitoring said characteristic periodically during charging and computing the slope of the variation of said monitored characteristic with time, for storing the maximum and minimum values of the so-computed slope values and comparing each successively computed slope value with the stored maximum and minimum values to identify the occurrence of the first-mentioned inflection point by identifying, from the so-compared slope values, a change in sign of the second derivative of the variation of the characteristic with time, and for controlling said supply means on the basis of the so-identified occurrence.

An apparatus for rapidly and efficiently charging a battery of the type having a characteristic associated therewith that varies with the state of charge of the battery and in which the variation of the characteristic with time during charging exhibits an opposed pair of inflection points prior to the battery attaining substantial full charge, each inflection point characterized by a change in sign of the second derivative of the variation of the characteristic with time, said apparatus comprising:

• means for supplying electrical energy to the battery for charging thereof;
• and
• means connected to said supply means for monitoring said characteristic periodically during charging and computing the slope of the variation of said monitored characteristic with time, for storing the maximum and minimum values of the so-computed slope values and comparing each successively computed slope value with the so-stored maximum and minimum values to identify the occurrence of the last inflection point of said opposed pair by identifying, from the so-compared slope values, a change in sign of the second derivative of the variation of the characteristic with time, and for controlling said supply means on the basis of the so-identified occurrence.

An apparatus for rapidly and efficiently charging a battery of the type having a characteristic associated therewith that varies with the state of charge of the battery and in which the variation of the characteristic with time during charging exhibits an inflection point prior to the battery attaining substantial full charge and another inflection point that precedes the first-mentioned inflection point, each inflection point characterized by a change in sign of the second derivative of the variation of the characteristic with time, said apparatus comprising:

• means for supplying electrical energy to the battery for charging thereof;
• and
• means connected to said supply means for monitoring said characteristic periodically during charging and computing the slope of the variation of said monitored characteristic with time, for storing the maximum and minimum values of the so-computed slope values and comparing each successively computed slope values with the stored maximum and minimum values to identify a sequence of said preceeding and first-mentioned inflection points by identifying, from the so-compared slope values, changes in sign of the second derivative of the variation of the characteristic with time, and for controlling said supply means on the basis of the so-identified occurrence.

An apparatus for rapidly and efficiently charging a battery of the type having a characteristic associated therewith that varies with the state of charge of the battery and in which the variation of the characteristic with time during charging exhibits a first and a succeeding inflection point prior to battery attaining substantial full charge, each inflection point characterized by a change in sign of the second derivative of the variation of the characteristic with time, said apparatus comprising:

• means for supplying electrical energy to the battery for charging thereof;
• and
• means connected to said supply means for monitoring said characteristic at least periodically during charging and computing the slope of the variation of said monitored characteristic with time, for storing the maximum and minimum values of the so-computed slope values and comparing each successively computed slope value with the so-stored maximum and minimum values to identify a sequence of the first and succeeding inflection points by identifying, from the so-compared slope values, changes in the sign of the second derivative of the variation of the characteristic with time, and for controlling said supply means on the basis of the so-identified sequential occurrence.

An apparatus for charging a nickel-cadmium battery of the type having a voltage characteristic associated therewith that varies with the state of charge of the battery and in which the variation of the voltage characteristic with time during charging exhibits an inflection point prior to the battery attaining substantial full charge and another inflection point that precedes the first-mentioned inflection point, each inflection point characterized by a change in sign of the second derivative of the variation of the voltage characteristic with time, said apparatus comprising:

• means for supplying electrical energy to the battery for charging thereof;
• and
• stored-program controlled means connected to said supply means for monitoring said voltage characteristic periodically during charging and computing the slope of the variation of said monitored voltage characteristic with time, for storing the maximum and minimum values of the so-computed slope values and comparing each successively computed slope value with the stored maximum and minimum values to identify the occurrence of the first-mentioned inflection point by identifying, from the so-compared slope values, a change in sign of the second derivative of the variation of the voltage characteristic with time, and for controlling said supply means on the basis of the so-identified occurrence.