Stack models require consideration of interactions between cells owing to practical variation of cell model parameters and different location/environment in the stack leading to thermal, electrical and mass transfer gradients. A previously developed voltage/current distribution model (electrical interaction) was extended and validated using two types of anomalies (bus plate material change, partially inactive cell located at the stack center), two anomaly locations and one or two anomalies within the stack. A measurement method for the principal cell interaction damping factor is discussed which can be used to easily and approximately predict the number of cells that are impacted by an anomaly. (c) 2005 Elsevier B.V. All rights reserved.