Electric power tool system

An electric power tool system comprises a tool main body (10), a battery pack (30) detachably attached to the tool main body, and a first charger (50, 150, 250; 350; 450; 550) that charges the battery pack. The first charger comprises a rechargeable battery (56) that supplies current to at least one rechargeable battery (34) of the battery pack. The at least one rechargeable battery of the first charger preferably has a larger charge storage capacity than the at least one rechargeable battery of the battery pack.