Abnormality detection device and battery system

An abnormality detection device comprising:

• a voltage measurement circuit connected to positive electrodes of a plurality of cells with a plurality of voltage measurement lines, respectively, the voltage measurement circuit being connected to a negative electrode of a lowest cell among the plurality of cells with a ground line, the plurality of cells being connected in series to one another, the voltage measurement circuit being configured to measure voltages of the plurality of cells;
• a plurality of input resistors connected to the plurality of voltage measurement lines, respectively;
• a plurality of capacitors connected between two adjacent voltage measurement lines among the plurality of voltage measurement lines and between the ground line and a voltage measurement line among the plurality of voltage measurement lines which is connected to the lowest cell, respectively, the plurality of capacitors constituting low-pass filters with the plurality of input resistors, respectively;
• a plurality of discharge circuits connected between the two adjacent voltage measurement lines and between the ground line and the voltage measurement line connected to the lowest cell at respective nodes which are closer to the voltage measurement circuit than the low-pass filters;
• and
• a control circuit configured to execute equalization processing on the plurality of cells by controlling the plurality of discharge circuits based on the voltages of the plurality of cells measured by the voltage measurement circuit, wherein
• each of the plurality of discharge circuits includes a discharge resistor and a switch connected in series to the discharge resistor, and
• the control circuit is configured to:
• turn on a switch of a certain channel and turn off the switch of the certain channel at a predetermined time after turning on the switch of the certain channel;
• and
• when a voltage of a channel immediately upper than the certain channel exceeds a threshold voltage when a predetermined period of time elapses from the turning off of the switch, determine that an abnormality occurs in a voltage measurement line among the plurality of voltage measurement lines between the certain channel and the channel immediately upper than the certain channel.