Balancing Resistor-based Online Electrochemical Impedance Spectroscopy: Opportunities and Limitations

Active dissipative balancing systems are widely used in battery systems. A lower boundary for the necessary balancing current is the difference in the leakage current of batteries in the system. The use of balancing resistors for the excitation of lithium-ion battery cells to determine their impedance has been discussed for almost decades. The value of impedance spectroscopy for in-depth battery cell diagnostics, such as temperature or aging, is currently being demonstrated and recognized by vehicle manufacturers, chip producers, and academia. This work systematically and quantitatively investigates how and under which circumstances the excitation can be performed via the balancing resistors already used in the battery management system and where limitations may lie. If individual cells or modules are to be replaceable, the balancing current must be so high that it can also be used for online electrochemical impedance spectroscopy.