An experimental validation of the adoption of dc-dc converters for the impedance measurement in Li-Ion batteries

Electrochemical Impedance Spectroscopy (EIS) is one possible technique to determine the State of Health (SOH) in Li-Ion batteries. This article describes some challenges involved in the implementation of EIS analysis in a battery charger. As an application example, some design issues on the control of power converters that can be used to perform the EIS analysis are addressed. The description focuses on several aspects, from the development of the measurement channels for current and voltage to the design of the perturbation signal control system. The device performances are tested in several conditions such as to determine the impedance of a singular Li-ion cell having 3.63 V and 2.6 Ah, but also in a small-scale battery pack having 25.2 V and 11.2 Ah, using different perturbation signals.