Battery system monitoring apparatus and electric storage device including the same

A battery system monitoring apparatus for monitoring a cell group having a plurality of battery cells connected in series, the battery system monitoring apparatus comprising:

• a cell controller integrated circuit (IC) which monitors and controls the states of the plurality of battery cells of the cell group;
• a battery controller which controls the cell controller IC;
• a plurality of voltage detection lines for measuring the voltage across the terminals of the battery cells, the voltage detection lines connecting positive and negative electrodes of the battery cells, respectively, to a plurality of voltage input terminals of the cell controller IC;
• a power line which connects the positive electrode of the battery cell having the highest potential among the plurality of battery cells to a power supply terminal of the cell controller IC;
• and
• a ground line which connects the negative electrode of the battery cell having the lowest potential among the plurality of battery cells to a ground terminal of the cell controller IC;
• and
• an RC filter circuit including the plurality of voltage detection lines, one of the plurality of voltage detection lines being a middle voltage detection line, and a remainder of the plurality of voltage detection lines not including the middle voltage detection line being connected to the middle voltage detection line through a capacitor.