How much gross energy does a laptop or notebook PC actually use (part 2)?

       

Here you see what can be observed at the input terminals of the PC power supply, in the first row with the full load of both the PC being operated and the battery being charged simultaneously, in the second row with the PC alone when the battery is full.

When you shut the PC down the residual power intake is only more 0.8W. With the active power being as low as this it becomes obvious from the view of the curve as well as from the measured values that the reactive current from a filter capacitor now prevails the total current.

Now let us unplug the PC and view the charger alone: The no-load consumption is as low as 0.07 W! While the price of this AC adapter is nothing much higher than any common branded model on the market, you may really wonder why so many other electronic devices have such high stand-by / idle / no-load losses. Remember how happy we were and what a progress it then was - only a few weeks ago - when we discovered how you can reduce the "off" consumption of a desktop PC from 6 W to 2 W!