An automatic estimation procedure for estimating a battery's state-of-charge includes predicting the state-of-charge using a state model that includes a state-transition matrix. An observation model then uses an observability matrix in connection with predicting a measured value of a parameter. State noise, the covariance of which is characterized by a state-noise covariance matrix contaminates this prediction. Similarly, measurement noise, the covariance of which is characterized by a measurement covariance matrix, contaminates this prediction. The values of these covariance matrices are then adjusted during the estimation procedure.