BATTERY CONTROL DEVICE AND BATTERY SYSTEM

A battery control apparatus which can calculate a state of charge of a battery with high accuracy is provided. The battery control apparatus of the invention determines whether or not an open circuit voltage of a battery cell is within a high sensitivity range in which the open voltage of the battery cell changes by a specified amount or more with respect to a change in the state of charge of the battery cell, and if within the high sensitivity range, calculates the state of charge by using a previously held correspondence relation table between the state of charge of the battery and the open voltage, and if not within the high sensitivity range, uses a previous state of charge calculation result stored in a storage part.