In order to protect being over charged, it is necessary to control the end point of charge. When the cell is fully charged, some special appearances can suggest the charge is final。 Usually there are 6 methods to protect the battery being over charged:
1） Peak voltage: measuring a cell’s peak voltage can judge charge is end;
2） dT/dt control: measuring a cell’s peak temperature change ration can judge the charge is end.
3） △T control: the temperature difference between the cell and the ambient as the cell is fully charged will be the biggest.
4） -△V control: as the cell is fully charged, its voltage will drop to a certain value.
5） Time control: generally the time which takes necessarily to charge 120% nominal capacity is set to control the end of charge.