Abstract: A method (20 or 30) and system (40) for estimating a battery state of charge can include a memory (48) for storing at least one among an impedance value, a plurality of values for V drop 0-1, or a plurality of values for V drop 0-1 normalized for charge or discharge values providing a stored plurality of values. The system can include a processor (44) and can measure at least one among V drop C-0 providing a measured V drop C-0 value and V drop 0-1 for the providing a measured V drop 0-1 value. The processor can be programmed to perform the functions of dividing the V drop C-0 value by the impedance value to estimate a charging current at the battery or comparing the measured V drop 0-1 value with a value among the stored plurality of values to estimate the battery state of charge.