Patent ID: 8054046

Claim:
A method for determining an initial diffusion voltage (V diff ) initial as a starting point when calculating a diffusion voltage V diff in an electrochemical cell, comprising: obtaining a time difference t off between a time when the cell was last turned-OFF and a time when the cell was next turned-ON; selecting a starting diffusion voltage (V diff )stat based on t off ; determining a trial diffusion voltage V diff based on a diffusion circuit model and (V diff ) start ; calculating an error voltage V error =(V diff )−|V OFF −V ON | where V OFF and V ON are cell voltages at cell turn-OFF and cell turn-ON respectively; repeating the foregoing determining and calculating steps using for each iteration (V diff ) start =(V diff ) previous +V error until V error is less than or equal to a first predetermined tolerance amount ε; storing in a memory a value of V diff corresponding to the condition V error ≦ε; and setting (V diff ) initial equal to the just stored value of V diff .