It may be connected to the load and the charging device, provided with at least one battery comprising a battery cell and a battery pack including a battery management unit that controls charging and discharging to the load of the battery from the charging device of the battery do. The battery management unit is to estimate the current amount of said battery cell on the basis of the measurement unit, the cell voltage data and the current data to measure the cell voltage and current of the battery cell, and generates a cell voltage data and current data, the current capacity of generating capacity data estimating unit, the cell voltage data and on the basis of the current data to estimate the current internal resistance of the battery cell, the internal resistance estimating unit that the current generates an internal resistance data, and the current capacity data and the include the current data based on the internal resistance estimating unit that estimates the physical condition health (SOH) of the battery cell.