Select Impedance> Fit a Model. In the resulting dialog box, select the Randles.mdl model. A dialog box appears which displays the fit parameters. In the Randles Cell dialog box, enter starting values for the fit parameters as follows:
Rf = 100
Cf = 0.001
Ru = 10
The fit algorithm requires initial estimates for all the parameters that are adjusted to yield the best fit. Extremely poor initial estimates can cause fitting problems.
Notice that the values that you have entered are not very good estimates. Your entered values are: Rf = 100 Ω, Cf = 0.001 F, and Ru = 10 Ω. The real values for the parameters are: Rf = 3010 Ω ± 1%, Cf = 1 µF ± 5% and Ru = 200 Ω ± 1%.
Continue the tutorial.