BMS500 fluxgate transducer is made of an excitation magnetic ring and a control circuit. Under normal conditions, the control circuit generates a fixed excitation current frequency to alternately place the magnetic core at the maximum saturation point. When the measured current flows, the primary current is measured by detecting the symmetry of the saturation point. The BMS series is suitable for battery monitoring systems that require high accuracy and low offset. It can realize the isolation measurement between the primary current (high voltage) and the secondary current (12V system). PHEV and EV system may use different technologies of batteries. One very important parameter that mayinfluence the stability of the SOC is the temperature. The battery temperature affects vehicle performance, reliability, safety and lift-cycle cost. The BMS500 series is qualified between -40 to 85 but the transducer shows a better accuracyinarestricted temperature range in order to deliver a very accuracy current measurement.