 The galvanostatic performance of a pristine lithium iron phosphate (LFP) electrode is investigated. Based on the poor intrinsic electronic conductivity features of LFP, an empirical variable resistance approach is proposed for the single particle model (SPM). The increasing resistance behavior observed at the end of discharge process of LFP batteries can be justified by the increased ohmic resistance, a resistive-reactant feature of LFP as the positive electrode active materials. The model is validated for two different laboratory made Li/LFP coin cells: a high-energy and a high-power configuration. Comparisons between the experimental results and the model predictions reveal that a variable resistance is successful to tackle the increasing overpotential.