An impact screw/bolt driver comprising: - a motor unit with a motor accommodated in a main housing of the screw/bolt driver and adapted to produce a rotary motion, as well as an operating switch for operating the motor , - a tool-holder shaft which is rotatable about a rotation axis (R), - a transmission unit with a percussion mechanism connected between the motor unit and the tool-holder shaft , - an electronic control system , containing at least one electronic control board, connected to two electric batteries and to the operating switch , wherein the transmission unit interacts with the motor and with the tool-holder shaft so as to transmit the rotary motion from the motor to the tool-holder shaft for rotating the tool-holder shaft about the rotation axis (R), characterized in that the impact screw/bolt driver comprises a handlebar structure with two gripping handles for manually gripping the wrench , wherein the electric motor is simultaneously powered by two rechargeable batteries connected in parallel to each other and accommodated together in the main housing , wherein the electronic control system comprises a device for generating the current supplied to the motor , configured to use a first battery of the batteries for generating a first phase of a three-phase current, a second battery (4") of the batteries for generating a second phase of the three-phase current, and both first and second batteries (4', 4") for generating a third phase of the three-phase current, wherein the ratio of the contributions of the first battery and second battery (4") to the generation of the third phase is determined depending on the residual charge state of the batteries (4', 4"), wherein the least charged battery (4'; 4") contributes less to the generation of the third phase than the most charged battery (4"; 4'). - a motor unit with a motor accommodated in a main housing of the screw/bolt driver and adapted to produce a rotary motion, as well as an operating switch for operating the motor , - a tool-holder shaft which is rotatable about a rotation axis (R), - a transmission unit with a percussion mechanism connected between the motor unit and the tool-holder shaft , - an electronic control system , containing at least one electronic control board, connected to two electric batteries and to the operating switch , wherein the transmission unit interacts with the motor and with the tool-holder shaft so as to transmit the rotary motion from the motor to the tool-holder shaft for rotating the tool-holder shaft about the rotation axis (R), characterized in that the impact screw/bolt driver comprises a handlebar structure with two gripping handles for manually gripping the wrench , wherein the electric motor is simultaneously powered by two rechargeable batteries connected in parallel to each other and accommodated together in the main housing , wherein the electronic control system comprises a device for generating the current supplied to the motor , configured to use a first battery of the batteries for generating a first phase of a three-phase current, a second battery (4") of the batteries for generating a second phase of the three-phase current, and both first and second batteries (4', 4") for generating a third phase of the three-phase current, wherein the ratio of the contributions of the first battery and second battery (4") to the generation of the third phase is determined depending on the residual charge state of the batteries (4', 4"), wherein the least charged battery (4'; 4") contributes less to the generation of the third phase than the most charged battery (4"; 4'). <EOS>