Lithium-ion batteries are one of the most preferred energy storage materials with their high energy density for numerous applications, including electric vehicles, hybrid electric vehicles, mobile phones, notebooks, battery-powered vehicles [1-4]. Performance of the lithium- ion batteries in the vehicle systems determine the safety, durability, reliability, and efficiency [5]. Equivalent circuit models are used to estimate the performance of lithium-ion cells due to concerning battery dynamic parameters. To improve the reliability of model-based battery management systems, equivalent circuit models have been extensively investigated, as reported in [6-10]. There are generally two terms that define the state of lithium-ion batteries, namely state-ofcharge and state-of-health [11]. The state-of-charge can be defined as the quantified value of the usable energy of battery, while the remaining performance is indicated by the state-of-health [12]. In the literature, the studies have also been performed to determine the state-ofcharge and state-of-health [8, 13]. Battery management systems use the term state-of-charge to observe the state of the battery and avoid over-charging or over-discharging [14]. The state-of-charge as a substantial parameter for a battery management system can be estimated if the battery’s open circuit potential is known. The open circuit potetial thermodynamically reflects the battery’s equilibrium potential under zero-current loading. Therefore, the open circuit potential is crucial to design a robust battery management system in real world operating conditions.