To provide a simplified and economical battery charging method, in which the end of charging operation can be detected with a temperature and the influence on environment of battery can be reduced.

This battery charging method comprises a step for periodically measuring (E2) the battery temperature and a change of temperature of the battery per unit time and a step, in which the charging mode is stopped (E5), by comparing temperature change per unit time with a first threshold (X+Y °C per minute), corresponding to change of ambient temperature and battery temperature, herein the charging mode is stopped (E5) and comparison is made only with the ambient temperature change (X °C per minute), and by comparing (E4) change of battery temperature per unit time with a second threshold (Y °C per minute) corresponding only to temperature change of the battery.