A protective unit for galvanic cells, which are interconnected into a battery by way of contact elements that are connected in a suitable manner to pole connections of said cells, can be associated with individual cells of a battery. The protective unit comprises an activation unit (1008, 1108, 1208, 1011, 1111) for the activation thereof. When the protective unit is activated, said protective unit bypasses the associated cell by changing the interconnection and thus takes it electrically out of the battery assembly.