I have two systems lets system A & system B, System A which is a well known system and working fine enough to rely on.
I took Impedance plot of a 4-Cell Pouch battery module with system A and made it my reference to compare impedance plot of system B.
Now the scenario is the impedance plot gets matched all along instead of some high frequency points on imaginary axis i.e. Y-axis below zero at x-axis as can be seen in the attached picture below, it goes a little longer as compared to reference.
Frequency Range is same for both the plots that is 1Khz - 0.1 hz.
The problem i want to highlight, why isn't it matching what are the possible reasons behind that?
Expert opinion required.
Hi,
Difference between the two Nyquist diagrams is tiny. Have you changed the way to connect the battery ? Have a look at
https://www.bio-logic.net/wp-content/uploads/20101105-application-note-5.pdf
It would be better if you plot diagrams in orthonormal scale. Have a look at
https://demonstrations.wolfram.com/OrthonormalScalesInANyquistDiagram/
jpd
Those plots are far to similar to address the tiny differences. High frequency impedance can be very sensitive to setup, so if the cell cable(s) are in slightly different configuration/spacing you can see differences there. Differences at lower frequency are (in general) more likely to be related to some cell difference but 1. there isn't enough data shown here to say anything about it (you can try going to lower frequencies to get more) and 2. even if there is a real difference there there are far too many variables in full cell battery impedance spectra to figure it out with only two spectra/cells.
Dear Farhan Farooq,
are you sure, that such low Z-values (some mOhms), are well inside your (EIS) set-up (current, Voltage and power) specs for this, full, freq. range (1 kHz : 0.1 Hz) ?
Also, could you show a similar plot (or a Z-spectrum) for a dummy (some mOhms) resistor ?
What is the model of your EIS system ?
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