A battery storage system, for supplying electrical power to at least one electrical vehicle function, which is redundantly connected to the battery storage system by a first supply branch and a second supply branch includes a first connection and a second connection configured to connect to the first and the second supply branches; at least one ground connection; a connection line, which connects the first and the second connections; a cross-isolating switching apparatus arranged in the connection line and configured to interrupt the connection line; a first energy storage unit connected to the connection line between the first connection and the cross-isolating switching apparatus; and a second energy storage unit connected to the connection line between the second connection and the cross-isolating switching apparatus.