8.2.3 Charging of valve regulated batteries at constant current (two step method) The battery shall be charged: – at a constant current of 2 In (see 7.1.2), until the voltage reaches 14,40 V; – then at a constant current of In for 4h. 8.2.4 Charging of valve regulated batteries at constant voltage and constant current (two step method) The battery shall be charged: – at a constant voltage of 14,40V ± 0,10 V for 20 h with the maximum current limited to 5 In (see 7.1.2), – then with a constant current of 0,5 In for 4 h. NOTE If neither complete knowledge of the battery construction nor a specification from the manufacturer is available, then charging according to the present subclause (8.2.4), is recommended.