State-of-charge estimation enhancing of lithium batteries through a temperature-dependent cell model

State-of-Charge estimation is one of the most important task of Battery Management Systems in hybrid and electric vehicles. Knowing the amount of charge stored in each cell of the vehicle battery pack is indeed crucial for effective battery utilisation that prevents cells from damaging and extends the battery lifetime. This is even more relevant for lithium batteries that are less tolerant to overcharging and deep discharging. However, State-of-Charge estimation is a difficult task to be performed online in a vehicle. This is because of the noisy and low accurate measurements and the wide operating conditions in which the vehicle battery can operate. This paper shows that the use of temperature-dependent cell model can improve State-of-Charge estimation, as temperature changes dramatically affect lithium battery behaviour. Experimental evidence is provided using the developed temperature-dependent cell model of Lithium-polimer battery inside a promising State-of-Charge estimator that mixes the standard Coulomb counting, i.e. battery current integration, with the model-based approach.