Patent ID: 7688075

Claim:
A method for creating a look-up table of cell resistance versus state of charge for a lithium sulfur battery of a particular type and determining the capacity thereof, said method comprising the steps of: a) charging said battery until a voltage across said battery increases to a predetermined maximum voltage; b) continuing to charge said battery at said predetermined maximum voltage until an input current to said battery decreases to a predetermined minimum current; c) measuring a cell resistance for said battery, said cell resistance being defined as the cell resistance at 100% state of charge for said particular type of lithium sulfur battery; d) recording said cell resistance at 100% state of charge; e) discharging said battery at a discharge rate to a predetermined lower cutoff voltage and recording a discharge time period; f) integrating said discharge time period with said discharge rate and storing the result, said integration result being defined as the battery capacity for said particular type of lithium sulfur battery; g) measuring a cell resistance for said battery, said cell resistance being defined as the cell resistance at 0% state of charge for said particular type of lithium sulfur battery; h) recording said cell resistance at 0% state of charge; i) charging said battery with a predetermined percentage of said battery capacity so that a present battery state of charge exceeds a previous battery state of charge; j) measuring a cell resistance for said battery, said cell resistance being defined as the cell resistance at the present state of charge for said particular type of lithium sulfur battery; k) recording said cell resistance at the present state of charge; l) repeating said steps (i), (j), and (k) until the present state of charge of said battery equals said battery capacity for said particular type of lithium sulfur battery; and m) creating said look-up table of cell resistance versus state of charge for state of charge values from 0% to 100%.