Technical developments of electric vehicles have been progressed very actively. Especially there are great technical achievements of battery for the electric vehicles to store energy from the outside source. Also there are numerous efforts for improvement charging infrastructure and charging system of the battery. And that is supporting this technology. For example On-Board Charger (OBC) is a battery charging system attached to the vehicle to operate the car. On-Board Charger is designed in manner of consideration such subjects: control via communication with other vehicle’s controller, improve the reliability as the security part, decrease of the life span of the battery due to temperature change during charging and discharging process, high cost of using parts for the high current rating and limitation of increasing the battery capacity. In this paper, there will be a deep discussion of designing and implementing the On-Board Charger to attach to the vehicles, which has superior cooling quality by effective radiant heat design and vibration and shock resistant design