Rapid Measurement of the Internal Impedance of Batteries up to 100VDC

Rapid impedance measurements have been proven to be an effective way of monitoring battery health, remaining useful life, and stability/safety. Dynexus Technology, in collaboration with Montana Tech, is developing an inline rapid impedance spectroscopy system that can measure battery modules and packs up to 100V. The high-voltage requirements led to modifications in the base system design for the current driver module, battery sensing and control, as well as enhanced protection. A different calibration approach was also implemented for the system. Testing the 100V prototype demonstrated successful offsetting of the battery DC voltage with minimal residual to ensure all the bits of resolution are focused on the battery response to an impedance measurement excitation. Batteries up to 78V were successfully measured as well. Using a reference test cell, the 100V prototype showed a resolution of less than ±45 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mu\Omega$</tex>.