This paper presents an electrical battery model for lithium-ion (Li-ion) batteries that can be used for dynamic simulations of hybrid electric non-road mobile machinery (NRMM) and other vehicles. Although the model has been developed mainly for large vehicle batteries with Li-ion based chemistries, it can be used for other battery chemistries as well. The parameters can be extracted from simple measurement sets. The model calculates e.g. state-of-charge, terminal voltage, and open-circuit voltage. In this paper, the model structure and parameter extraction are explained in detail, and a model for a 25.9 V lithium-ion polymer battery module with 40 Ah cells is presented. Parameters are extracted from experimental measurements and the model is validated by making another experiment with more realistic hybrid electric NRMM current profile.