Day by day mobile robots are being used more often in the industry and even by households. Energy is one of the running costs of robots and it can be quite significant specifically due to heavy usage. In such cases energy consumption can be reduced by programming the robots to utilize more efficient motion profiles. This paper develops energy minimizing motion profiles for two wheel differential drive robots. The approach utilizes an objective function that uses a power model that combines the dynamic models of the robot and the motors. The problem, which also takes into account variable payload masses, is solved using a Hamiltonian function approach leading to a solution in closed form for the speed profiles. Energy consumption of the generated speed profiles are experimentally compared to trapezoidal speed profiles and significant savings in energy are found.