Method and apparatus for evaluating a rechargeable battery

1. A computer-implemented method for evaluating a battery employed in an application, comprising:

during a charging event,

monitoring a voltage response with respect to a charge input for the battery;

monitoring a battery charging current for the battery;

determining a battery charge capacity based upon the monitored battery charging current for the battery;

determining a derivative of the voltage response with respect to the change in battery charge capacity;

identifying a first peak in the derivative of the voltage response corresponding to a low battery charge capacity;

identifying a second peak in the derivative of the voltage response corresponding to a high battery charge capacity;

determining a state of charge of the battery based upon the second peak; and

determining a state of health of the battery based upon the battery charge capacity at which the second peak occurs, including;

determining threshold battery charge capacities indicative of battery state of health levels; and

comparing the battery charge capacity at which the second peak occurs with the determined threshold battery charge capacities indicative of battery state of health levels; and

controlling operation of the application in response to the state of charge and the state of health.

2. The method of claim 1 , wherein the charging event comprises a low current charging event.

3. The method of claim 1 , wherein determining a state of health of the battery comprises:

estimating a decreasing state of health based upon the second peak occurring at decreasing battery charge capacity values.

4. A system for evaluating a battery employed in an application, comprising:

the battery;

a computerized control module, including programming configured to:

during a charging event,

monitor a voltage response with respect to a charge input for the battery;

monitor a battery charging current for the battery;

determine a battery charge capacity based upon the monitored battery charging current for the battery;

determine a derivative of the voltage response with respect to the change in battery charge capacity;

identify a first peak in the derivative of the voltage response corresponding to a low battery charge capacity;

identify a second peak in the derivative of the voltage response corresponding to a high battery charge capacity;

determine a state of charge of the battery based upon the second peak; and

determine a state of health of the battery based upon the battery charge capacity at which the second peak occurs, including;

determining threshold battery charge capacities indicative of battery state of health levels; and

comparing the battery charge capacity at which the second peak occurs with the determined threshold battery charge capacities indicative of battery state of health levels; and

control operation of the application in response to the state of charge.