Reducing heterogeneities between battery elements is paramount to ensure good performance and lifetime of this type of storage system. Since second life batteries may be more heterogeneous than fresh batteries, quantifying and limiting cell spread is an important task. This paper proposes an experimental and modelling study of cell spread in a second life battery module. The capacity spread in a battery module that has been used in an electric vehicle for several years is presented. The battery modelling study also highlights the detrimental effect of an outlier cell on the overall performance of the battery. This study is a first step towards considering this dispersion in the modelling and diagnosis of reused batteries.