A proximal end portion of a robotic surgical arm is to be coupled to an adapter of a surgical robotic platform, for use during a surgical session at the platform, and then decoupled from the adapter for storage until being re-coupled for use during another surgical session at the platform. A resonant-mode transformer-coupled power converter is provided that has a secondary side and a primary side. The secondary side is in the arm and has a transformer secondary coil in the proximal end portion of the arm. The primary side has a transformer primary coil in the adapter. The primary and secondary coils are held at positions and orientations that enable mutual inductive coupling between them for operation of the power converter when the arm is coupled to the adapter. Other embodiments are also described and claimed.