Battery charging method and device thereof

The invention discloses a battery charging method and device thereof. The method includes the following steps. First, the temperature of all battery blocks of a batter module is detected while the batter module is charged by stable current or voltage. If one of temperatures of blocks is higher than a first threshold, the charging current is decreased. The first threshold is lower than the critical voltage defined by safety standard for decreasing the charging current. Then, the block's temperature is checked whether or not it tends to decrease. If the block's temperature tends to decrease, the charging current is kept, else, the charging current is decreased continuously. Therefore, the battery module can be charged safely and without losing the capacitance of the battery module.