Patent ID: 7092830

Claim:
A method for estimating the discharge curve of an electrochemical cell, comprising the steps of: a) subjecting a first cell to a first shorter-term accelerated discharge test having a shortest total time on test, thereby generating a first discharge curve; b) subjecting a second cell to a second shorter-term accelerated discharge test having a longer total time on test than the first cell, thereby generating a second discharge curve; c) subjecting a third cell to a longer-term accelerated discharge test having a longer total time on test than either the first or second cells, thereby generating a third discharge curve, wherein the first, second and third cells are of a similar chemistry and construction; d) offsetting the second and third discharge curves so that they intercept with the first discharge curve at a pre-determined similar percent depth-of-discharge; e) calculating a first and second series of slopes for the first and second cells, respectively, from the intercept to an end percent depth-of-discharge at incremental depths-of-discharge; f) calculating a rotational angle between the first and second series of slopes at each incremental depth-of-discharge; g) utilizing the rotational angles from step f) to estimate the third discharge curve from the intercept point to the end percent depth-of-discharge to determine when the third cell is reaching its end of life; and h) replacing the third cell with a fresh cell prior to the third cell reaching its end of life.