Battery Testing Methods · Last reviewed 2026-09-16
| Measurement | What it captures | Detail level |
|---|---|---|
| Conductance | Single AC read, inverse of resistance | One number — health proxy |
| DC resistance | Resistance under load or pulse | One number |
| Impedance (EIS) | Resistance across frequencies | Separates internal processes |
Conductance is the field-tool read; impedance spectroscopy is the laboratory read. The field tool tells you that the battery is degrading; the impedance sweep begins to tell you where — see resistance and conductance for the single-number version.
At high frequencies the signal sees mostly the ohmic path (connectors, electrolyte resistance); at mid frequencies it sees the charge-transfer at the electrode interface; at low frequencies it sees diffusion inside the active material. Each band reacts differently to sulfation, corrosion and drying, so the swept measurement separates the aging mechanisms instead of blending them into one number.
Position: Impedance testing is the difference between knowing a battery is failing and knowing why it is failing — the field tools triage, the frequency sweep diagnoses, and the two belong together in any serious battery evaluation.
Reasoning: A single resistance number is a health score without a cause. The impedance sweep decomposes that score into its mechanisms, which is exactly what warranty, research and large-fleet decisions need — the diagnosis, not just the verdict.
This is the author's editorial view, not a purchasing guarantee.
Return to Battery Testing Methods · World Battery Hub. Informational, not purchasing advice.