The invention relates to a replacement cell (20) for a battery system, said battery system comprising a housing (15) with two battery terminals (2) which are attached to the housing and are electrically connected to the replacement cell (20). Furthermore, the replacement cell (20) has a circuit (12) which is designed to identify the balancing parameters of the balancing method of a battery system, said balancing method being used to equalize the charge between the battery cells of the battery system, and to carry out an autonomous balancing procedure of the charge state of the replacement cell (20) using said balancing parameters.