On checking the resistance of a cell, I am getting a very high negative resistance (-15 M) and low positive resistance when I exchange the DMM terminals (i.e. check cell from opposite electrodes). MY EIS curve also starts from negative imaginary and real resistance. Can anyone tell me what is the physical interpretation of that? Any explanation would be appreciated. Thank you.
Mmm...
Either :
- Your multimeter is broken. ;-)
- The thing you are measuring is not a resistor. Means:
Lets state : V = R(I)*I
For this component, R(I) has a strong dependency on I. It is not constant.
A resistor is typically a component where R(i) is constant.
- Initial assesment (from the negative reading) seems it includes a voltage source.
(This is a guess. It can be another non-linearity too.)
H.
If the cell is an electrochemical one, then its electrodes are polarized and the cell voltage is added or subtracted from the voltage applied by the instrument in order to measure the resistance. This is a reason to get bizarre results.
Never measure the resistance / conductance of a solution using direct current. AC mode is required to avoid electrolysis.
Thank you Cornel Radu Can you tell me what do you mean when you say "electrodes are polarized". Also as the DMM is a standard instrument used commonly to measure voltage of a cell, I have no choice. How can I measure resistance of my cell using AC mode? My cell is galvanic and not electrolytic.
The method you describe (using the function R of a digital multimeter) is not appropriate for measuring the INTERNAL resistance of a galvanic cell. You have to add a load resistor.
See:
https://www.translatorscafe.com/unit-converter/en-US/calculator/batt-internal-resistance/
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