pmsetcommand, which is used to manipulate power management settings, can be used on a Mac laptop running Apple's OS X operating system to obtain information regarding the alternating current (AC) adapter being used to power the laptop.
-g ac / adapter will display details about an attached AC power adapter. Only supported for MacBook and MacBook Pro.
E.g., the output below is from a MacBook Pro laptop with an Apple 85W MagSafe Power Adapter model number A1343 plugged into it.
$ pmset -g ac Wattage = 85W Revision = 0x0000 AdapterID = 0x0100 Family Code = 0x0085 Serial Number = 0x00981dc6