The engineering decision
Use the resistance measurement that represents the load decision, and keep its method, time or frequency, SOC and temperature attached to the value.
Have these inputs ready
- Application load duration and amplitude
- Available pulse or impedance data
- SOC, temperature and rest conditions
- Measurement bandwidth and sense points
Pulse response and recovery
Scroll horizontally to view the full diagram →
The observation window is part of the result
With discharge current defined as positive, use Rapp(t) = [Vbefore − V(t)] / [I(t) − Ibefore]. State the voltage and current sampling points and retain the same sign convention throughout the report. The baseline, current transition and loaded-voltage sample define the measured response.
Values measured after 100 ms and 10 s can both be correct for their procedures while answering different engineering questions.
Different techniques can agree when relevant observation timescales and conditions match. The method name alone does not mean results must differ.
Equivalent-circuit elements are model parameters
Resistors and capacitors can approximate ohmic, interfacial and transport behavior. They are not literal separate parts inside the cell, and a fitted resistor is not automatically equivalent to datasheet DCIR.
The cited nonlinear EIS study analyzes parameter identifiability in a physical single-particle model. Applying that lesson to engineering model selection means checking whether the available data constrain the chosen parameters; a good fit alone does not establish a unique physical interpretation.
References: Nonlinear Electrochemical Impedance Spectroscopy for Lithium-Ion Battery Model Parameterization
Control the operating condition before comparing values
SOC, temperature, rest history and aging move the result. Fixture contact, sampling rate, filtering and current-source rise time can move the measured value as well.
Use four-wire sensing to remove most current-lead drop from the voltage measurement, then state the exact terminal points and timing.
Measurement & validation procedure
| Test / review | Record | Acceptance condition |
|---|---|---|
| Define the engineering question | Load amplitude, duration, SOC and temperature range | Selected method observes the timescale needed for the decision |
| Freeze the procedure | Excitation, sampling, fixture, rest and calculation | Another laboratory can reproduce the reported value |
| Correlate to the application | Resistance result and representative loaded-voltage trace | Prediction error is known across required conditions |
Continue this engineering task
Related engineering guidance
Prepare the evidence for review
- Load timescale and voltage window
- Complete measurement procedure
- Raw synchronized current/voltage data
- Correlation against the required duty
Technical sources & claim support
References support the stated engineering principles. Worked examples use their explicitly stated assumptions.
- A study of the influence of measurement timescale on internal resistance characterisation methodologies for lithium-ion cells ↗
Scientific Reports 8, 21 (2018); abstract and Figure 7: comparison at matched measurement timescales
Peer-reviewed cell study. Numerical values apply only to the tested cells, SOC, temperature and equipment.
- Comparison of Several Methods for Determining the Internal Resistance of Lithium Ion Cells ↗
Sections 4–5: DC step, AC resistance, impedance spectroscopy and pulse-duration effects
Peer-reviewed method comparison. The proposed timing and cell values are not universal acceptance requirements.
- Nonlinear Electrochemical Impedance Spectroscopy for Lithium-Ion Battery Model Parameterization ↗
Structural parameter identifiability and conclusions: nonlinear single-particle model
Peer-reviewed primary research. Single-particle physical model; extending the identifiability lesson to other model families is an engineering inference.
- Keysight: How to Test Coin Cell Batteries ↗
Coin Cell Battery Testing and Modeling: four-wire sensing, pulse resistance, pulse width/rest time and defined cutoffs
Measurement principles illustrated with coin cells. Select the current profile, fixture, sampling, temperature and cutoff conditions for the actual cell or pack.
Key claims and evidence
| Claim | Basis | Reference |
|---|---|---|
| Pulse resistance changes with the voltage-sampling interval | documentation | A study of the influence of measurement timescale on internal resistance characterisation methodologies for lithium-ion cells; Comparison of Several Methods for Determining the Internal Resistance of Lithium Ion Cells |
| The nonlinear EIS study analyzes structural and practical identifiability in a single-particle model | documentation | Nonlinear Electrochemical Impedance Spectroscopy for Lithium-Ion Battery Model Parameterization |
| Four-wire connection removes most current-lead drop from the sensed voltage | documentation | Keysight: How to Test Coin Cell Batteries |