Constant current charging method is applying a constant current to the battery with low percentage of current ripples independent of the battery state of charge or temperature.The abbreviation for this method is CC in the literature.This is achieved by varying the voltage applied to the battery using control techniques such as current mode control to keep the current constant.In the split rate CC different rates of current are applied based on SOC，time of charge，voltage，or combination of them in different stages of charging.This gives more accurate and balanced charging and circuits should be used to avoid over-voltage of the cells.