Traction energy storage system for a vehicle, comprising: several electrical energy storages, wherein each of the energy storages comprising cell modules electrically connected via bus bars, a contactor, an energy storage high-voltage interface, and an energy storage controller controlling the contactor, wherein each of the cell modules comprises several storage cells and a cell module controller, and the cell module controllers are configured to output measured values relating to the storage cells in the respective cell module, and the energy storage controllers are configured to determine a storage state dependent on the measured values of the cell modules in the respective energy storage, and wherein, in each energy storage, the contactor is configured to connect the bus bars of the energy storage to the energy storage high-voltage interface of the respective energy storage as specified by the energy storage controller in a closed position of the contactor and to disconnect them in an open position of the contactor; a system high-voltage interface connected or connectable to the vehicle, which is connected to the energy storage high-voltage interfaces of the energy storages, wherein the energy storage high-voltage interfaces of the energy storages are connected in parallel; and a system controller configured to receive a vehicle instruction for connecting energy storages currently disconnected by the open position, to query the storage states (504; 506) of the currently disconnected energy storages, to assign the currently disconnected energy storage to one or more clusters based on the queried storage states, and to connect the energy storages by closing the contactors via the respective energy storage controllers in accordance with the cluster assignment; wherein each of the storage states specifies an open-circuit voltage of the respective energy storage and the currently disconnected energy storages are assigned to the clusters depending on the open-circuit voltages; and wherein the energy storages assigned to one of the clusters are connected when the voltage of the system high-voltage interface matches a range defined by the open-circuit voltages of the energy storages of the cluster. several electrical energy storages, wherein each of the energy storages comprising cell modules electrically connected via bus bars, a contactor, an energy storage high-voltage interface, and an energy storage controller controlling the contactor, wherein each of the cell modules comprises several storage cells and a cell module controller, and the cell module controllers are configured to output measured values relating to the storage cells in the respective cell module, and the energy storage controllers are configured to determine a storage state dependent on the measured values of the cell modules in the respective energy storage, and wherein, in each energy storage, the contactor is configured to connect the bus bars of the energy storage to the energy storage high-voltage interface of the respective energy storage as specified by the energy storage controller in a closed position of the contactor and to disconnect them in an open position of the contactor; wherein each of the cell modules comprises several storage cells and a cell module controller, and the cell module controllers are configured to output measured values relating to the storage cells in the respective cell module, and the energy storage controllers are configured to determine a storage state dependent on the measured values of the cell modules in the respective energy storage, and wherein, in each energy storage, the contactor is configured to connect the bus bars of the energy storage to the energy storage high-voltage interface of the respective energy storage as specified by the energy storage controller in a closed position of the contactor and to disconnect them in an open position of the contactor; a system high-voltage interface connected or connectable to the vehicle, which is connected to the energy storage high-voltage interfaces of the energy storages, wherein the energy storage high-voltage interfaces of the energy storages are connected in parallel; and a system controller configured to receive a vehicle instruction for connecting energy storages currently disconnected by the open position, to query the storage states (504; 506) of the currently disconnected energy storages, to assign the currently disconnected energy storage to one or more clusters based on the queried storage states, and to connect the energy storages by closing the contactors via the respective energy storage controllers in accordance with the cluster assignment; wherein each of the storage states specifies an open-circuit voltage of the respective energy storage and the currently disconnected energy storages are assigned to the clusters depending on the open-circuit voltages; and wherein the energy storages assigned to one of the clusters are connected when the voltage of the system high-voltage interface matches a range defined by the open-circuit voltages of the energy storages of the cluster.