LI-ion Battery Impedance Measurement

Mon 20.07.2026

How can you quickly assess the true condition of a battery without invasive testing? Impedance analysis with the Bode 500 enables non-invasive diagnostics of Li-ion cells, helping to identify degradation and gain key insights for development and testing.

Non-invasive Diagnostics of Li-ion Batteries Using Impedance Analysis

How can you quickly assess the true condition of a battery without invasive testing? OMICRON Lab presents a practical application approach showing how to measure the impedance of Li-ion cells using the Bode 500 analyzer and gain valuable insights into their condition.

Why measure battery impedance?

Battery impedance is not just a single value - its frequency-dependent behavior reveals:

• State of Health (SOH)
• signs of degradation
• changes depending on the State of Charge (SOC)

The key advantage is that this is a non-invasive method - there is no need to disassemble or destructively stress the battery.

How does the measurement work?

The OMICRON Lab application note demonstrates the method:Shunt-Thru with series resistance (Rs)This method is ideal for:

• very low impedances in the mΩ range
• safe measurements even for fully charged cells (e.g., 4.2 V)

The series resistors act as a voltage divider, protecting the analyzer inputs while still enabling accurate measurements.

Measurement setup

A typical configuration includes:

• Bode 500 (impedance analyzer + FRA + VNA in one device)
• B-AMP 12 (signal amplification, improved SNR)
• B-LCM (suppression of ground loop errors)
• series resistors (e.g., 500 Ω)

The physical setup is also critical - short cables, coaxial connections, and minimizing parasitic effects are essential for accurate results.

What can you learn from the measurement?

Practical results show:

• Li-ion cell impedance around 50 mΩ at 1 kHz
• capacitive behavior at low frequencies
• transition to inductive behavior at higher frequencies
• impedance varies with voltage (SOC), e.g.:
  • higher voltage → lower impedance

In other words: the battery is a dynamic system - its impedance changes with its condition and operating state.

Who is this solution for?

• battery system development (R&D)
• automotive and e-mobility
• cell testing and validation
• power electronics and power supply design

What are the benefits?

• fast diagnostics without damaging the battery
• deeper understanding of cell behavior
• ability to track degradation over time

More details in the application note

You can find the complete measurement procedure, setup, and result interpretation here:

Open OMICRON Lab Application Note - Battery Impedance Measurement