MANAGEMENT DEVICE, AND ELECTRICITY STORAGE SYSTEM

A cell voltage measurement unit measures a voltage of each of a plurality of cells that are series-connected. A total voltage measurement unit measures a total voltage of the plurality of cells. A controller manages an internal impedance of each of the plurality of cells. The controller detects a ripple of the total voltage measured by the total voltage measurement unit, estimates a ripple of each cell voltage by multiplying the detected ripple of the total voltage by a ratio of the internal impedance of each cell to a resultant internal impedance of the plurality of cells, and determines whether the ripple of each cell voltage is within an allowable voltage range.