In this paper, optimization of operating conditions for electrochemical energy sources is attempted using a dynamic optimization approach. This rigorous approach is demonstrated using a nonlinear diffusion equation that governs the mass transport limitation from/to the planar electrode. The resulting differential-algebraic model is solved using piecewise constant control vector iteration method that uses vectorized discharge current. The results obtained using the optimal control profile is compared with constant current discharge method and also with another trial and error approach that uses linear current control. It is found that the optimal control method achieves 12% more state of discharge against constant current discharge method with better energy efficiency and battery use. The proposed approach can be extended to complex systems such as operating electrochemical energy sources in hybrid environments that require proper control of energy distribution among the hybrid components.