Regenerative braking is an effective approach for electric vehicles to extend their efficiency. It is the emerging technology used on hybrid gas/electric automobiles to recoup some of the energy lost during stopping. Regenerative braking has to be carried out together with the conventional barking. In brake system design for electric vehicles, the basic equation must be concerned, one is properly applying braking force to quickly reduce the vehicle speed and meanwhile maintain the vehicle traveling direction stable and controllable through the steering wheel on various road conditions and also recovering the braking energy as much as possible in order to improve the energy utilization efficiently. The regenerated energy is saved in a storage battery and used later to power the motor. Regenerative braking takes energy normally wasted during braking and turns it into usable energy. It does improve energy efficiency of the vehicle. In this work, a mathematical model of a regenerative braking system for the braking efficiency has been developed. The experimental results are compared with the simulated results. The electricity generated by the battery during braking varies accordingly to the speed of the vehicle. So to utilize the generated electricity completely a suitable Electronic Control Unit is designed.