1. Method to recursively estimate a state associated with an electrical energy storage device, comprising: a) constructing an executable multivariate mathematical model of the electrical energy storage device operable to estimate a state associated with the electrical energy storage device, comprising: an equation summing a plurality of sensed data signals, each sensed data signal factored by: one of a corresponding plurality of weighting factors; and further factored by one of a corresponding plurality of parameters; b) sensing each of the sensed data signals at a time-certain; c) updating each of the plurality of parameters, comprising: i) creating a weighted recursive least squares equation to calculate a parameter based upon the executable multivariate mathematical model of the electrical energy storage device; and, ii) executing the weighted recursive least squares equation to calculate each of the parameters, based upon: the sensed data signals at the time-certain, the weighting factors, and, non-corresponding parameters determined at a preceding time-certain; and d) executing the multivariate mathematical model of the electrical energy storage device to estimate the state associated with the electrical energy storage device using the updated plurality of parameters, the sensed data signals at the time-certain, and the weighting factors.