Protective circuit having a connection for a charging device for a mobile electrical battery store such as a battery store in a motor vehicle , and having a grid connection which is connected to a busbar of the protective circuit via a protection arrangement , and a grid charging current (I N ) is able to be supplied to the charging device via the grid connection and the busbar of the protective circuit , - and having a stationary battery store which is connected to the busbar between the protection arrangement and the charging device via a controllable voltage converter , - and having a current measuring device which is designed to measure the total charging current (IG) flowing from the busbar to the charging device , - and having control electronics which are connected to a signal output of the current measuring device and to a control input of the controllable voltage converter , - wherein the total charging current (IG) to the charging device consists, firstly, of the grid charging current (I N ) and, secondly, of a battery charging current (I B ), supplied in a controlled manner via the voltage converter , of the stationary battery store , and control electronics are designed to set the current proportions of the supplied battery charging current (I B ) and of the supplied grid charging current (I N ) in such a way that the grid charging current (I N ) does not exceed a predefined maximum current (I max ), characterized in that - the control electronics are designed, as charging time (t) elapses, to increase the proportion of the supplied battery charging current (I B ) in the total charging current (IG) in such a way that the proportion of the grid charging current (I N ) in the total charging current (IG) is below the predefined maximum current (I max ) by a predefined safety margin (ΔS). - and having a stationary battery store which is connected to the busbar between the protection arrangement and the charging device via a controllable voltage converter , - and having a current measuring device which is designed to measure the total charging current (IG) flowing from the busbar to the charging device , - and having control electronics which are connected to a signal output of the current measuring device and to a control input of the controllable voltage converter , - wherein the total charging current (IG) to the charging device consists, firstly, of the grid charging current (I N ) and, secondly, of a battery charging current (I B ), supplied in a controlled manner via the voltage converter , of the stationary battery store , and control electronics are designed to set the current proportions of the supplied battery charging current (I B ) and of the supplied grid charging current (I N ) in such a way that the grid charging current (I N ) does not exceed a predefined maximum current (I max ), characterized in that - the control electronics are designed, as charging time (t) elapses, to increase the proportion of the supplied battery charging current (I B ) in the total charging current (IG) in such a way that the proportion of the grid charging current (I N ) in the total charging current (IG) is below the predefined maximum current (I max ) by a predefined safety margin (ΔS). <EOS>