How much gross energy does a laptop / notebook PC actually use?

clipped from www.leonardo-energy.org Submitted by Stefan Fassbinder on Fri, 2009-03-20 12:23. The gross energy consumption to get back the 150 Wh consumed before (see last week) is 200 Wh. Note that this latter figure includes all losses incurred by both the charger and the charge-discharge cycle of the batteries! So we are faced with a pretty good overall efficiency of the process being as high as 75%, and we can say that the gross power consumption of this portable PC when used off the line, including all charge-discharge and conversion losses, is between 11 W and barely 40 W. The battery operating time is between 5 and 18 hours. This energy is put back in place within 4 hours, as you see here. After 1:15h the internal battery is full, and the charging of the supplementary one starts.