In this paper, it investigates that the battery is the separation factor of direct current microgrid system. It compares experimental value with a simulation value that incorporates the performance of the equipment actually used by means of the integrated value of the electric energy. From the comparison, it focuses electric discharge condition. Under the condition, it assesses and investigates separation factor of battery of direct current microgrid system. It can see the end in sight long operations of direct current microgrid system to improve Prediction accuracy of simulation by specifying and revising the separation. It can indicate optimal value of cost and battery volume and so on about each equipment of direct current microgrid system.