Between christmas and new year 2004, I bought an energy counter. You plug it into the socket and attach the desired device to it - and it displays which voltage, amperage, power etc. it uses.
The first thing I tested was my Travelmate here are the results:
Table 13.1. Power consumption of my Travelmate
| Device | State | Consumption in Watt |
|---|---|---|
| AC adaptor | not plugged into laptop | 6 W |
| connected with off-state laptop, not loading | 0 W | |
| Laptop | loading, 1.6GHz | 37 W |
| loading, 600MHz | 37 W | |
| loaded, 1.6GHz | 32 W | |
| loaded, 600MHz | 27 W | |
| loaded, LCD off, 1.6GHz | 27 W | |
| loaded, LCD off, 600MHz | 22 W |
The "loading" states were mesured when the battery was loaded about 50%. With increasing percentage (from 85 or so) the laptop uses less power, even when loading.
It seems not to make a difference if the machine is idle or compiling something - it uses the same power.
All in all: I never thought the laptop would consume so few power. My desk light needs 20W, and with 600MHz and LCD off the notebook is nearly equal.
For those who wonder: In Germany we have a voltage of 250V.