Patent ID: 8836340

Claim:
An assembled battery system, comprising: an assembled battery having a plurality of serially-connected battery cells; voltage detecting lines connectable at one ends to electrodes of the battery cells of the assembled battery as a voltage measurement target; electric resistors serially-connected at one ends to the other ends of the voltage detecting lines; capacitors connected to the other ends of the electric resistors, each of the capacitors being configured to electrically interconnect one of the voltage detecting lines and the other voltage detecting line; voltage measuring circuits connected respectively to each of the voltage detecting lines and configured to detect an electric potential difference between one of the voltage detecting lines and the other voltage detecting line; electrically openable short-circuiting switches arranged between the capacitors and the voltage measuring circuits and parallel-connected to the capacitors, the voltage measuring circuits being configured to obtain a first measurement result by measuring an electric potential difference appearing between the opposite ends of the short-circuiting switches when one of the short-circuiting switches is opened and the other short-circuiting switches electrically adjoining to the opposite ends of one of the short-circuiting switches are opened, the voltage measuring circuits being further configured to obtain a second measurement result by measuring an electric potential difference appearing between the opposite ends of the short-circuiting switches when one of the short-circuiting switches is closed and the other short-circuiting switches electrically adjoining to the opposite ends of one of the short-circuiting switches are opened; and a monitoring circuit configured to detect a difference between the first measurement result and the second measurement result with respect to each of the short-circuiting switches and to detect at least one of a failure based on the difference between the first measurement result and the second measurement result.