Patent ID: 8041523

Claim:
A battery charge/discharge current detection apparatus having a power supply circuit powered by a battery mounted on a vehicle and configured to detect a charge/discharge current of the battery by use of a current detecting resistor connected between a negative terminal of the battery and a ground, the battery charge/discharge current detection apparatus comprising: a first function of detecting a voltage across the current detecting resistor; a second function of detecting a charge/discharge current of the battery on the basis of the voltage detected by the first function; a third function of detecting presence of an abnormality of the current detecting resistor; a fourth function of informing the abnormality detected by the third function to the outside; a fifth function of forming a bypass of the current detecting resistor when the third function detects the abnormality of the current detecting resistor; and a sixth function of producing a state where the voltage across the current detecting resistor is virtually zero, and performing a zero-point correction for the second function in the produced state; wherein a battery-side negative terminal of the power supply circuit is connected to the negative terminal of the battery.