Battery monitoring apparatus

A battery system, comprising:

• a battery pack that is configured by a plurality of battery cells connected in series to each other;
• and
• a battery monitoring apparatus that includes:
• a plurality of connection lines that are connected to each of a pair of positive and negative electrode terminals of each of the plurality of battery cells;
• a monitoring circuit that is provided with a pair of sensing terminals for each pair of positive and negative electrode terminals of each of the plurality of battery cells, and that includes a voltage detection circuit which detects a cell voltage applied to the pair of sensing terminals;
• a first filter circuit that is provided in a pair of connection lines of the plurality of connection lines connected to the pair of sensing terminals and removes noise generated between the pair of connection lines;
• and
• a second filter circuit that removes noise,
• wherein:
• the plurality of connection lines includes
• a plurality of common lines that are connected to a plurality of common terminals which are located between adjacent battery cells of the plurality of battery cells and shared between a negative electrode terminal of a high-potential side battery cell of the adjacent battery cells and a positive electrode terminal of a low-potential side battery cell of the adjacent battery cells, and
• first and second branch lines that are branched from each of the common lines, the first branch line being connected to the negative electrode terminal of the high-potential side battery cell, the second branch line being connected to the positive electrode terminal of the low-potential side battery cell;
• the first filter circuit includes
• first resistors that are located on the first and second branch lines connected to the pair of sensing terminals, and
• a first capacitor that is located between the first and second branch lines connected to the pair of sensing terminals;
• and
• the second filter circuit includes
• a second resistor that is located on the plurality of connection lines, and
• a second capacitor that is connected in series between the plurality of connection lines without passing through the first resistors and the second resistor.