The use of green energy is becoming increasingly more important in today’s world. Therefore, electric vehicles are currently the best choice for the environment in terms of public and personal transportation. Because of its high energy and current density, lithium-ion batteries are widely used in electric vehicles. Unfortunately, lithium-ion batteries can be dangerous if they are not operated within their Safety Operation Area (SOA). Therefore, a battery management system (BMS) must be used in every lithium-ion battery, especially for those used in electric vehicles. In this work, the battery is evaluated by calculating the state of charge, state of life, charging and discharging control and by cell balancing algorithm. High precision estimation can maintain the battery cells working in a good situation and extend the service life of the battery pack, reducing the cost of use indirectly. This is meaningful for Li-ion battery’s industrial application.