AC adapter, batteries and laptops

[Firestrider]

Do AC adapters for laptops work just like PSUs in a typical desktop? Is there any other power generation in a laptop besides this and the battery? What is the efficiency of the AC adapter to computer components, AC adapter to battery, and battery to computer components?

[Sam__]

laptop adaptors usually put out between 15 and 19v iirc so I presume that then gets converted into 12, 5 and 3.3 after entering the laptop.

[Firestrider]

I have an AC adapter for my laptop rated for 65W at 19.5V with Efficiency Level IV (I can't seem to find more on this)