Abstract: A method and apparatus are provided for estimating a state of charge (SOC) of a battery. Curves are generated to expresses a relationship between a first parameter and an SOC over a region of interest. A voltage and a current of the battery during a period of time are measured to create a set of voltage and current data, which is then processed to create a set of processed data. The processed data is then combined with the generated curves to generate processed data as a function of SOC. A curve is generated that evaluates each SOC for accuracy and chance likelihood of fit. An SOC that minimizes both the error and chance is selected and output for display to the user on a user interface.

Abstract: A method and apparatus for estimating a state of charge of a battery.

Abstract: Method and system are disclosed for determining individual string resistance in a network of strings when the current through a parallel connected string is unknown and when the voltage across a series connected string is unknown. The method/system of the invention involves connecting one or more frequency-varying impedance components with known electrical characteristics to each string and applying a frequency-varying input signal to the network of strings. The frequency-varying impedance components may be one or more capacitors, inductors, or both, and are selected so that each string is uniquely identifiable in the output signal resulting from the frequency-varying input signal. Numerical methods, such as non-linear regression, may then be used to resolve the resistance associated with each string.

Abstract: The subject invention pertains to a method and apparatus for recalibrating and/or estimating a battery's state of charge (SOC). The subject invention is advantageous in situations where the battery infrequently, if ever, reaches a full charge and/or a full discharge. In a specific embodiment, the subject method and apparatus can utilize a battery's voltage and/or current, and/or changes in a battery's voltage and/or current with time, to recalibrate and/or estimate the battery's SOC. The method and apparatus of the subject invention can monitor various parameters relating to the condition of the battery in order to determine where on the open circuit voltage (OCV) versus SOC curve, the dOCV/dSOC versus SOC curve, and/or d2OCV/dSOC2 versus SOC curve the curve the battery is and, in a specific embodiment, when the battery reaches inflection point of the OCV versus SOC curve.