Patent ID: 7879502

Claim:
A method for revising a polarization curve that defines the current/voltage relationship of a fuel cell stack, said method comprising: defining a reference polarization curve at a first point in time; revising the reference polarization curve at a later point in time to match the actual polarization curve of the stack when the stack current density is below a predetermined threshold by changing a first adaptation value; and revising the reference polarization curve at a later point in time to match the actual polarization curve of the stack when the stack current density is above the predetermined threshold by changing a second adaptation value, wherein the first adaptation value defines an absolute voltage difference between the predicted average cell voltage of fuel cells in the stack and the average cell voltage of the reference polarization curve for a particular stack current density, and the second adaptation value defines a current dependent voltage difference between the predicted average of cell voltage of fuel cells in the stack and the average cell voltage of the reference polarization curve for the particular stack current density.