an alerting method for recharging a battery of a mobile device . the method includes collecting measured data with the mobile device , comparing the measured data with a statistic model of recharging patterns of the mobile device , determining if it is currently a suitable time for charging the battery of the mobile device according to a predetermined relation in the statistic model , and alerting a user of the mobile device to recharge the battery if it is currently a suitable time for charging the battery of the mobile device .