If you load it with hydrogen and wait at OCP that the PdH is in its transition between the alpha and beta phase, the potential is extremelly stable ( order of 2 mV) . The duration of this transition depends on the length, radius and roughness of your wire... In my case (electrodeposited Pd with a charge of 4 C cm-2) I used it for 1 entire day, but my Pd was nanostructured, so fast kinetics of deintercalation.