POWER TOOL SYSTEM AND BATTERY PACK THEREOF

A power tool system includes a first and second power tools with different rated-voltages and a battery pack supplying power to the corresponding power tool. The battery pack has a battery module with two battery cell groups and a female connector having four conductive terminals respectively connected to positive and negative electrodes of two battery cell groups. The female connector has a converter switching the connection of two battery cell groups between parallel connected state to isolated connected state through connecting or disconnecting two conductive terminals with same polarity together. The first power tool includes a first male connector connected to the female connector to connect two battery cell groups in series through connecting two conductive terminals with different polarities together. The second power tool has a second male connector coupled to the female connector to connect two battery cell groups in parallel through connecting two conductive terminals with same polarity together.