A battery management unit for a battery system with a conductor or a busbar, the battery management unit including a printed circuit board, and a fluxgate current sensor including a magnetic core having a through-hole, at least one excitation winding, at least one compensation winding, and a sensor circuit configured to measure a magnetization of the at least one excitation winding, to generate a driving signal for driving the at least one compensation winding, to generate a current flowing through the at least one compensation winding according to the driving signal, and to generate an output signal corresponding to a magnitude of an electric current flowing through the through-hole of the magnetic core, wherein the magnetic core, the at least one excitation winding, the at least one compensation winding, and the sensor circuit are each integrated into the printed circuit board.