Apparatus comprises: an induction, coil (40) arrangement, the induction coil arrangement having a first set of at least one coil (41) with a first diameter and a second set of at least one coil (42) with a second diameter, the second diameter being different to the first diameter, a first tap (A) connected at a first end of the first set, a second tap (B) connected at connection common to a second end of the first set and a first end of the second set, and a third tap (C) connected at a second end of the second set; a power transmit arrangement (61) selectively connectable to a first combination of two of the first to third taps; and a power receive arrangement (62) selectively connectable to a second combination of two of the first to third taps, the second combination being different to the first combination.