Estimating battery capacity or State of Charge (SoC) is indispensable when using the battery as a backup of electrical energy for various applications. Examples of battery applications that are used are trend mobile devices, electric vehicles, renewable energy, and many other applications. SoC batteries can be estimated using several techniques available today, mostly based on battery modeling. There are at least three models that have been introduced in recent developments today. Three known battery models are electrochemical models, ana-lyticaUmathematical models, and electrical circuit models. In this paper, we use battery modeling based on electrical circuit models to analyze the characteristics of battery parameters during the discharging process. The reason is, using this model will be easier to analyze the measurement data such as voltage, current, and internal resistance values as parameters to estimate SoC.