Battery system with a current detection circuit

A battery system provided with batteries and a current detection circuit comprising:

• a current detection resistor connected in series with the batteries;
• an amplifier that amplifies voltage induced across the terminals of the current detection resistor;
• a detection circuit that detects the current flowing through the batteries from the amplifier output;
• and
• a voltage source circuit that supplies a test voltage to the input-side of the amplifier,
• wherein current detection lines connect the current detection resistor with the input-side of the amplifier, and the detection circuit stores a reference voltage corresponding to the current detection lines in the connected state,
• when the test voltage is supplied to the input-side of the amplifier from the voltage source circuit, the detection circuit compares the voltage input from the amplifier with the stored reference voltage, and detects current detection line open-circuit by the shift in voltage from the reference voltage.