Interpreting the components of cell voltage

Abstract

Several misconceptions are prevalent concerning the components of cell voltage. The equilibrium potential, also known as the decomposition potential or reversible potential frequently is confused with the voltage equivalent of the total energy required by the cell to reduce alumina. The voltage intercept of cell volts vs. current extrapolated to zero current is sometimes mistakenly taken to be the back emf or counter electromotive force of the cell. The value is consistently lower than the true back cemf. Pseudo resistance, the slope of cell volts vs. current, is frequently confused with the true ohmic resistance of the cell. This paper will define the various components of cell voltage, discuss how they can be determined and describe their use in cell control and diagnosis of operating problems.