High power battery system in which a large operating current flows, particularly for vehicle drivetrains, comprising - a battery system monitoring electronics and - a plurality of battery modules, each of which comprises at least one rechargeable battery cell, and which are electrically connected in series via an operating current line in such manner that, during operation, an operating current flows through the operating current line, wherein - an electrolyte and active materials are contained in the battery cell to store electrical energy, - the battery cell contains an electrolyte solution, which is based on SO 2, - at least one of the battery modules is constructed as a bypass battery module, which comprises a bypass switch and a bypass line, which are designed and arranged such that when the bypass switch has been switched from a normal operating position to a bypass position, the battery module is electrically bypassed by the bypass line so that the operating current flows through the bypass line, thereby avoiding an external short circuit of the battery cell of the battery module, - the battery system monitoring electronics comprises a module monitoring unit for each bypass battery module, which unit monitors the battery module and detects a fault state of the battery module, and - when a fault state of a battery module is detected by one of the module monitoring units, the battery system monitoring electronics measures the current flow in the operating current line and switches the bypass switch of the respective battery module from the normal operating position to the bypass position at a time when the current flow in the operating current line is lower than a predetermined limit value. - a battery system monitoring electronics and - a plurality of battery modules, each of which comprises at least one rechargeable battery cell, and which are electrically connected in series via an operating current line in such manner that, during operation, an operating current flows through the operating current line, - an electrolyte and active materials are contained in the battery cell to store electrical energy, - the battery cell contains an electrolyte solution, which is based on SO 2, - at least one of the battery modules is constructed as a bypass battery module, which comprises a bypass switch and a bypass line, which are designed and arranged such that when the bypass switch has been switched from a normal operating position to a bypass position, the battery module is electrically bypassed by the bypass line so that the operating current flows through the bypass line, thereby avoiding an external short circuit of the battery cell of the battery module, - the battery system monitoring electronics comprises a module monitoring unit for each bypass battery module, which unit monitors the battery module and detects a fault state of the battery module, and - when a fault state of a battery module is detected by one of the module monitoring units, the battery system monitoring electronics measures the current flow in the operating current line and switches the bypass switch of the respective battery module from the normal operating position to the bypass position at a time when the current flow in the operating current line is lower than a predetermined limit value.