Generally, for Li-ion and LiFePO4 battery type, recommended charge current should be limited between 0.5C and 0.1C, here "C" is the battery rating capacity. Higher charge current means shorter charge time, but also means more money; lower charge current means long charge time but can save your cost. For example, if your battery type is 4s 12.8V 10Ah LiFePO4 battery-pack, you can use 5.0A charge current (like our G100-12F4 charger), also you can choose 1.0A charge current (such as our P2012-F4 charger, output is 14.6v 1.5A). Using 5.0A charge current to charge an empty 10A LiFePO4 battery will take 3.5 hours, and if charge current is 1.5A then you will take 9 hours to charge this same battery. Obviously, if long charge time is not a problem for you, the economic charger choice should be P2012-F4.