Standard polarization tests in this work monitored the electrical discharge versus time after cycling from OCV to Rext (with Rext ranging from 300 and 3.5 kΩ) with a cycling period of approximately 1 to 2 hours. Switching between OCV and Rext at this time scale strongly limits any acclimation to the different applied Rext values during the polarization tests (i.e., avoiding in situ acclimation). Therefore, reaching stable voltages during standard polarization tests marks a short-term stability at each Rext value. To achieve a long-term stability at each Rext, a so-called "long-hold" polarization test was conducted in which Rext was applied for up to 15 hours after switching from OCV. This allowed acclimation to occur at each position on the power density curve (i.e., achieving in situ acclimation).