Question: how to calculate time of charging?
Answer: Charging time of battery = Battery Ah / Charging Current.
T = Ah / A.
Charging current for 120Ah Battery = 120 Ah x (10/100) = 12 Amperes.
Charging time for 120Ah battery = 120 / 13 = 9.23 Hrs.
Then 120 x (40 / 100) = 48 …..(120Ah x 40% of losses)