Conventionally known is a battery state detection device (battery sensor) that detects the state of a battery. Such battery state detection devices are disclosed in, for example, Patent Documents 1 and 2.
The battery state detection device of this type includes a battery post terminal for connection to a battery post, a shunt resistor, and a circuit board. The shunt resistor is electrically connected to the battery post terminal. The circuit board is configured to measure a current having flowed through the battery post terminal by measuring a potential difference across the shunt resistor.
The conventional battery state detection device is configured such that the shunt resistor and the battery post terminal are electrically and mechanically connected to each other by being fastened to each other with a bolt and a nut.