The charge factor is a characteristic value for batteries that establishes the relationship between the charging time, the nominal capacity and the charging current. It tells how long the charging time is for a battery with a certain C coefficient, which is the characteristic value for the charging capacity, at a corresponding charging current.
The charge factor is a dimensionless value and depends on the battery technology used and represents the efficiency of a battery during charging: With how much charge current must the battery be charged in order to be able to extract a certain amount of energy.
From a mathematical point of view, the charging time (h) is calculated by multiplying the charging factor by the nominal capacity (mAh), divided by the charging current (mA). The charge factors range between 1.2 and 1.5 depending on the battery type. Assuming a charge factor of 1.2 and a nominal capacity of 1,500 mAh, this means that the charging time takes twelve hours with a charge current of 150 mA. The charge factor drops at higher charge currents at >C/1.