Measurements with our MegaEIS

We performed measurements with our MegaEIS load at a redox-flow battery at Pinflow energy storage in Pilsen, Czech Republic. Our intention was to test whether it is possible to measure EIS at zero DC current flowing through the battery🔋. 
 
🎉 To achieve this goal, an external source was connected to booster terminals of the MegaEIS device. The MegaEIS was set up to consume exactly the same DC current as the external source was providing. In this way, the resulting DC current flowing through the battery was zero. Nevertheless, the DC current through the loads of the MegaEIS was non-zero, so we were able to stimulate AC oscillations of amplitude up to the DC value of current through the loads.

The redox-flow battery was a stack of 20 cells. We monitored the voltage at particular cells using our EVM cards. The MegaEIS we used is designed for maximal current 200 A. We performed several EIS measurements at various DC currents ranging from 10 A to 50 A with AC current amplitude 8 A (zero to peak amplitude).

📈 To taste the results see the figure below with Nyquist plots. According to Pinflow, the results are aligned with expectations. The EIS scan was performed in frequency range 50 kHz - 1 mHz. The DC current through loads was 20 A and correspondingly the DC current through external source was also 20 A.

Generally speaking, we are very satisfied with the results. We can immediately use our current MegaEIS loads for both lithium and redox-flow battery testing 🚀 .