Battery monitoring apparatus

A battery monitoring apparatus for monitoring a state of a storage battery, the battery monitoring apparatus comprising:

• an electric power supply terminal which is connected with a first electrical path and via which drive electric power for driving the battery monitoring apparatus is supplied from the storage battery to the battery monitoring apparatus through the first electrical path;
• a voltage input terminal which is connected with a second electrical path and via which a terminal voltage of the storage battery is inputted to the battery monitoring apparatus through the second electrical path so as to be measured by the battery monitoring apparatus;
• a signal control unit connected with a third electrical path and configured to cause a predetermined AC signal to be outputted from the storage battery to the battery monitoring apparatus through the third electrical path, the signal control unit being configured to cause the predetermined AC signal to be outputted from the storage battery with the storage battery itself being an electric power source for the output of the predetermined AC signal;
• a response signal input terminal which is connected with a fourth electrical path and via which a response signal generated by the storage battery in response to the output of the AC signal is inputted to the battery monitoring apparatus through the fourth electrical path;
• and
• a calculating unit configured to calculate, based on the response signal, a complex impedance of the storage battery,
• wherein
• at least one of the first electrical path, the second electrical path, the third electrical path and the fourth electrical path is merged with at least one other of the electrical paths into an electrical path that is connected to the storage battery.