A battery charging system for charging a exchangeable battery system (BSYS), which is provided for driving an electric motor, the exchangeable battery system (BSYS) comprising a plurality of integrated traction batteries (BAT1, BAT2), which, in an installed state of the battery system (BSYS), jointly supply the electric motor of an electric vehicle with electric power, comprising a plurality of battery charging units, wherein a battery charging unit (BLEI, BLE2) is provided for each of the plurality of traction batteries (BAT1, BAT2) integrated in the exchangeable battery system (BSYS), wherein the battery charging system has a DC charging plug (DC-LS1, DC-LS2) for each traction battery (BAT1, BAT2) integrated in the exchangeable battery system (BSYS), which is connected to an associated battery charger (BLG1, BLG2) of a battery charging unit (BLEI, BLE2) of the battery charging system, wherein each of the battery charging units (BLEI, BLE2) assumes one of several possible statuses, wherein the battery charging units (BLEI, BLE2) exchange their respective status with each other via a communication link of the battery charging system, in order to interlock operating state transitions between operating states of the battery charging system and to synchronize charging processes of the traction batteries (BAT1, BAT2) of the exchangeable battery system (BSYS) connected to the battery charging system via the DC charging plugs (DC-LS1, DC-LS2), and wherein during a charging process for charging the exchangeable battery system (BSYS) with the several integrated traction batteries (BAT1, BAT2), the battery charging system assumes one of several predetermined operating states and operating state transitions between the operating states of the battery charging system are linked to the statuses communicated by all the battery charging units (BLEI, BLE2). a plurality of battery charging units, wherein a battery charging unit (BLEI, BLE2) is provided for each of the plurality of traction batteries (BAT1, BAT2) integrated in the exchangeable battery system (BSYS), wherein the battery charging system has a DC charging plug (DC-LS1, DC-LS2) for each traction battery (BAT1, BAT2) integrated in the exchangeable battery system (BSYS), which is connected to an associated battery charger (BLG1, BLG2) of a battery charging unit (BLEI, BLE2) of the battery charging system, wherein each of the battery charging units (BLEI, BLE2) assumes one of several possible statuses, wherein the battery charging units (BLEI, BLE2) exchange their respective status with each other via a communication link of the battery charging system, in order to interlock operating state transitions between operating states of the battery charging system and to synchronize charging processes of the traction batteries (BAT1, BAT2) of the exchangeable battery system (BSYS) connected to the battery charging system via the DC charging plugs (DC-LS1, DC-LS2), and wherein during a charging process for charging the exchangeable battery system (BSYS) with the several integrated traction batteries (BAT1, BAT2), the battery charging system assumes one of several predetermined operating states and operating state transitions between the operating states of the battery charging system are linked to the statuses communicated by all the battery charging units (BLEI, BLE2).