Energy Management System reflecting battery capacity efficiency and method of the same

The present invention accurately charge than: to provide a system and method for managing a more accurate and efficient energy by counting the power-to-efficiency of the energy storage device to calculate (State of Charge SOC) screen more accurately calculate the SOC as for, a current measuring unit for measuring a current flowing through the battery and the capacity efficiency derivation unit for deriving a based on the size of the electric power input / output is changed in proportion to the capacity of the battery capacity efficiency value, from the current measuring unit to reflect the capacity efficiency values ​​derived from the measured current and the capacity efficiency derivation unit error is charged state of a complementary battery: and a SOC estimating unit for estimating (state of charge SOC), the SCO estimated by the SOC estimation based in comparison with the amount of change of the energy put into the battery and the amount of change in the actual SOC to each other by the energy loss to calculate the energy loss calculation unit, wherein Including the power value in consideration of the energy loss of assigning the power value calculated by the energy loss calculation unit assigning unit, and stores the power value assigned in the power value assigning unit store which provides power value stored during the battery charging and discharging parts of and there consists.