Patent ID: 8487629

Claim:
A battery system comprising: a voltage detection apparatus including a voltage detection portion which includes an AD converter which converts an analog voltage signal having a measurement target analog voltage into a digital voltage signal to output the digital voltage signal, a voltage level discrimination portion which is connected to a voltage detection line across which the analog voltage signal is delivered, and which discriminates a voltage level of the measurement target analog voltage to output a discrimination result, and a fault detection portion which detects, based on an output of the AD converter and an output of the voltage level discrimination portion, a fault in the voltage detection portion in a state in which a voltage value of the digital voltage signal is within a predetermined voltage range; a battery as a voltage source of the measurement target analog voltage; and a control portion which, when the fault detection portion detects the fault, limits discharging of the battery, or limits charging of the battery, or limits discharging and charging of the battery wherein the voltage level discrimination portion includes comparators which compare the measurement target analog voltage with predetermined reference voltages within the predetermined voltage range, and to detect the fault in the voltage detection portion in the state in which the voltage value of the digital voltage signal is within the predetermined voltage range, the fault detection portion compares the output of the AD converter and the output of the voltage level discrimination portion at a moment that an output of the comparators changes.