A battery-operated wristwatch comprising a watch case, a first strap part and a second strap part coupled to opposite sides of the watch case, and a clasp for closing the strap parts around a wearer's wrist, wherein the watch comprises a battery housing containing a battery for powering the watch case, and wherein: - the battery housing is integrated in the clasp, - one of the strap parts comprises power transmission wires, and is hereafter referred to as the power transmission strap part, - the battery housing is coupled to the power transmission strap part, by a first power transmitting coupling that allows the transmission of power to the watch case, through the power transmission strap part, wherein the power transmission strap part is coupled to the watch case by a second power transmitting coupling; said battery-operated wristwatch characterised in that the first power transmitting coupling is a rotatable coupling comprising: - a cylindrical rod having a circular cross-section, wherein a portion of the sidewall of the rod is immovably attached to a throat section, and wherein the rod further comprises rounded contacts spaced apart in the longitudinal direction of the rod and an isolating strip or groove adjacent to the throat section and extending at least from one end of the rod to a location beyond both of the rounded contacts, - a pair of spring-operated contacts spaced apart at the same distance as the pair of rounded contacts, - a hollow cylindrical bracket comprising a closed end and an open end, and a cutaway portion of the sidewall of the bracket extending between the closed and open end, said cutaway portion being configured to expose the pair of spring-operated contacts, and wherein: ∘ the open end comprises a blocking lobe configured to define a circular entry passage interrupted by a gap, the entry passage being dimensioned to allow the axial insertion of the rod into the bracket, while the gap allows the insertion of the throat section, ∘ the throat section is positioned so that the insertion or removal of the rod into or from the bracket is only possible at angular positions of the rod at which the isolating strip or groove is aligned with the spring-operated contacts, while at other angular positions, the rounded contacts are in contact with the spring-operated contacts when the rod is fully inserted into the bracket, - the angular positions at which the strip or groove is aligned with the spring-operated contacts are not accessible when the wristwatch is worn around the wrist of a user. - the battery housing is integrated in the clasp, - one of the strap parts comprises power transmission wires, and is hereafter referred to as the power transmission strap part, - the battery housing is coupled to the power transmission strap part, by a first power transmitting coupling that allows the transmission of power to the watch case, through the power transmission strap part, - a cylindrical rod having a circular cross-section, wherein a portion of the sidewall of the rod is immovably attached to a throat section, and wherein the rod further comprises rounded contacts spaced apart in the longitudinal direction of the rod and an isolating strip or groove adjacent to the throat section and extending at least from one end of the rod to a location beyond both of the rounded contacts, - a pair of spring-operated contacts spaced apart at the same distance as the pair of rounded contacts, - a hollow cylindrical bracket comprising a closed end and an open end, and a cutaway portion of the sidewall of the bracket extending between the closed and open end, said cutaway portion being configured to expose the pair of spring-operated contacts, and wherein: ∘ the open end comprises a blocking lobe configured to define a circular entry passage interrupted by a gap, the entry passage being dimensioned to allow the axial insertion of the rod into the bracket, while the gap allows the insertion of the throat section, ∘ the throat section is positioned so that the insertion or removal of the rod into or from the bracket is only possible at angular positions of the rod at which the isolating strip or groove is aligned with the spring-operated contacts, while at other angular positions, the rounded contacts are in contact with the spring-operated contacts when the rod is fully inserted into the bracket, ∘ the open end comprises a blocking lobe configured to define a circular entry passage interrupted by a gap, the entry passage being dimensioned to allow the axial insertion of the rod into the bracket, while the gap allows the insertion of the throat section, ∘ the throat section is positioned so that the insertion or removal of the rod into or from the bracket is only possible at angular positions of the rod at which the isolating strip or groove is aligned with the spring-operated contacts, while at other angular positions, the rounded contacts are in contact with the spring-operated contacts when the rod is fully inserted into the bracket, - the angular positions at which the strip or groove is aligned with the spring-operated contacts are not accessible when the wristwatch is worn around the wrist of a user.