Power consumption is an important issue for mobile robots that carry a limited energy source, like batteries, for a long period of time. A power model can relate the kinematic movements of the robot with the power values, giving an estimation of the energy needed for the robot to fulfill a specific task. In this study, a power model that is based on the dynamic parameters of the mobile robot and its motors is proposed. The model can predict the consumed power accurately, even when the robot carries different payloads and performs different accelerations. The experimental validation performed using a two wheeled differential drive robot shows both the accuracy of the proposed model and the influence of acceleration and the weight of the payload to the power consumption of the robot.