A system and method for charging a merchandise item is presented. A power supply system for charging the merchandise item includes: a power supply unit, a power cable with a cable control logic. The power supply unit includes a variable power supply and power supply control logic. The power supply can be attached at one end to a power socket of the merchandise item and at the other end to the power supply unit. The cable control logic reads a power requirement from a charge adaptor logic located near the end of the cable connected to the merchandise item and communicates it over the power cable to the power supply control logic. The power supply control logic controls the variable power supply based, at least in part, on the power requirement so that the variable power supply generates a supplied voltage onto the power cable to power the merchandise item.