A method of estimating a state of charge (SOC) and a state of health (SOH)
of an electrochemical cell (EC) includes modeling the EC with a linear
equation, measuring a terminal current of the EC, measuring a terminal
voltage of the EC and measuring a temperature of the EC. The linear
equation is processed through a time-varying state and parameter
estimator based on the terminal current, the terminal voltage and the
temperature to determine states and parameters of the EC.