At present, the propulsion system of majority of vehicles on the road still depends upon the combustion of fuels to extract the energy. Combustion is a high-temperature exothermic reaction in which oxygen reacts with the fuel and produces gaseous bi product. The expansion of high-temperature, high-pressure gas inside the engine produces useful work to propel the automobile. Once useful mechanical work is done, harmful gases such as COx and NOx are released into the atmosphere. The major concern bothering the governments globally is climate change and greenhouse effect primarily caused by the emissions of CO2. As a result, the transportation sector is constantly looking for alternative sources of energy to replace the fossil fuel-based engines. At this point of time, Electric Vehicles (EV)/Hybrid EV (HEV) becomes the life savior, since they mainly run or conversion of electrical energy into mechanical energy. The power source of the EV is the energy stored as chemical energy in Li-ion battery due to their inherent advantages such as lighter in weight, smaller in size, and low maintenance. Speaking about the Li-ion battery, battery management system (BMS) is an internal part of the battery pack. Therefore, this paper mainly focuses on the development of Simulink models of various battery technology and compare against each other. Also, to estimate the SOC as accurately as possible to balance the cells more efficiently, thereby storing significant amount of energy in the battery pack. This paper initially reviews the different battery packs for the Electric Vehicles (EV)/Hybrid EV (HEV), and later, a battery management system is proposed where the state-of-charge (SoC) is estimated accurately for different battery packs.