The steady state polarization curve

The steady state polarization curve showed that the current decreased smoothly and the voltage increased smoothly as the load resistance was increased from 0.2 to 11 Ω. When the load resistance was increased from 11 to 12 Ω both the steady state current and voltage decreased abruptly, but the fuel cell did not extinguish. The resistance was then increased stepwise from 12 to 20 Ω and the current decreased and voltage increased smoothly, but along a different trajectory. Starting with a load resistance of 20 Ω, the process was reversed and the load resistance was decreased stepwise by ∼ 1 Ω every 3–4 h. The current and voltage followed the same trajectory as seen for the high load resistance polarization curve, but there was no abrupt change in the current and voltage at 11 Ω. Instead the IV data varied smoothly until the resistance was decreased below 5 Ω, when it jumped to match the polarization curve taken with decreasing load resistance.