Automotive


How the latest BMS technology brings lab-grade battery diagnostics into EV platforms


By Wenzel Prochazka, BMS senior product manager for system innovation, NXP Semiconductors F


or years, the most revealing battery insights, including aging signatures, internal shorts, and hidden temperature gradients, lived in test labs, not in vehicles. That’s changing. And with it, so is the auto industry. By embedding electrochemical impedance spectroscopy (EIS) directly into battery management systems (BMS), engineers can actively analyse cells inside electric vehicles and energy-storage systems, without adding lots of extra sensors or stopping normal operation.


The payoff of moving real-time diagnostics into the real world is faster charging with better safeguards, safer daily use, and longer battery life, wrapped in a design and cost profile that works for mass production.


Why EIS is transformational Unlike traditional methods that infer battery health from estimation of internal resistance, open-circuit voltage rest periods, and surface thermistors that measure temperature, EIS nudges the battery


with an AC signal and measures how it responds at a few chosen frequencies. That response acts like a fingerprint of what’s happening inside the cell – from basic resistance to how easily ions move. Measuring just a small set of frequencies can deliver


quick, reliable signals that feed internal resistance and state-of-health estimates, as well as safety checks, going further than conventional checks that often blur multiple effects together.


In vehicles, a current-based method like


this often works best because modern lithium-ion cells have very low impedance. Instead of scanning hundreds of points in time, the BMS can focus on a handful that matter most for fast, accurate decisions.


Fast-charge safety and early fault detection


With fast charging, the risk isn’t just “too much current” – it’s where that current goes. EIS can spot the early signs of lithium plating, where metallic lithium starts to deposit on a battery’s anode, so the BMS can gently dial back or reshape the charge before damage from lithium sets in. It can also reveal patterns linked to small internal faults or tab issues that traditional resistance checks mostly miss. The result is more confident fast charging with fewer surprises.


EIS signals can also effectively track internal cell temperature. That means the BMS gains a window into core heating and temperature spread across the cell and the pack, providing


Fig.1 EIS performance comparisons between the cell with internal short-circuit and normal cells. 22 February 2026 Components in Electronics www.cieonline.co.uk


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