A surgical instrument system comprising: an end effector comprising a moveable cutting instrument; an electric motor communicating with the end effector for actuating the cutting instrument; a motor control circuit for controlling the motor, wherein the motor control circuit comprises: a power source connected to the motor for electrically powering the motor; a charge accumulator device; a switching circuit (S1, S2, S3) connected to the power source and the charge accumulator device for temporarily connecting the charge accumulator device to the power source to charge the charge accumulator device, and selectively connecting the charge accumulator device in series with the power source to provide additional power to the motor; and wherein the motor control circuit further comprises a current control circuit, connected to the power source, for varying the current supplied to the motor from the power source, such that the motor has: a first, high power operational mode for a first portion of a cutting stroke cycle of the cutting instrument; a second, low power operational mode for a second portion of the cutting stroke cycle of the cutting instrument, wherein the second portion corresponds to an end of the cutting stroke cycle of the cutting instrument. an end effector comprising a moveable cutting instrument; an electric motor communicating with the end effector for actuating the cutting instrument; a motor control circuit for controlling the motor, wherein the motor control circuit comprises: a power source connected to the motor for electrically powering the motor; a charge accumulator device; a switching circuit (S1, S2, S3) connected to the power source and the charge accumulator device for temporarily connecting the charge accumulator device to the power source to charge the charge accumulator device, and selectively connecting the charge accumulator device in series with the power source to provide additional power to the motor; and a power source connected to the motor for electrically powering the motor; a charge accumulator device; a switching circuit (S1, S2, S3) connected to the power source and the charge accumulator device for temporarily connecting the charge accumulator device to the power source to charge the charge accumulator device, and selectively connecting the charge accumulator device in series with the power source to provide additional power to the motor; and wherein the motor control circuit further comprises a current control circuit, connected to the power source, for varying the current supplied to the motor from the power source, such that the motor has: a first, high power operational mode for a first portion of a cutting stroke cycle of the cutting instrument; a second, low power operational mode for a second portion of the cutting stroke cycle of the cutting instrument, wherein the second portion corresponds to an end of the cutting stroke cycle of the cutting instrument. a first, high power operational mode for a first portion of a cutting stroke cycle of the cutting instrument; a second, low power operational mode for a second portion of the cutting stroke cycle of the cutting instrument, wherein the second portion corresponds to an end of the cutting stroke cycle of the cutting instrument.