2009-03-05
What seems to use power on a Dell Mini 12
Since I had a Mini 12 around and I'd previously done similar measurements with an Asus Eee PC, here are some measurements about what seems to draw power on a Dell Mini 12. The necessary disclaimers are that all of these measurements are made with a power meter while the Mini 12 was on wall power, running Dell's version of Ubuntu.
(Ubuntu exposes a lot more controls for this than Asus's Eee setup, so I suspect you could duplicate these results on battery power or opt to reduce power consumption at the expense of things like a dimmer display.)
| Minimal powered up state (screen turned off) |
5 watts |
| Screen | +3 watts (dimmest) to +6 watts (brightest) |
| 100% CPU usage, or playing a Youtube video | +3 watts |
| Hard drive fully active | +1 watt |
| Ethernet and wifi | no extra power usage |
(I couldn't detect a power difference from turning the wifi off and on; either it doesn't draw much power, or Ubuntu can't actually turn the wifi hardware off and hitting the 'wifi off' key combination just stops Ubuntu from listening to it.)
Or in other words, the Mini 12 draws between 5 watts (if left sitting
idle with the screen off) and 15 watts (at full activity). It draws 11
watts for my typical usage, with the screen at full brightness but the
system mostly idle.
As with the Eee, the best non-disruptive thing
you can do to save power is to power down the screen; unfortunately
there seems to be no screensaver setting to power the screen down
immediately when it's invoked, so I resorted to using 'xset dpms
force off' again.
Dell quotes the capacity of the Mini 12's normal battery at 24 watt-hours. At 11 watts for casual usage this predicts a bit over 2 hours of run time, which agrees with my experience. Given the power consumption for playing Youtube videos, the Mini 12 is probably not the machine to use for watching your own movies during boring airplane flights. (Well, not unless they give you power sockets. And I don't know if it has enough CPU power to play video at any significant resolution; I didn't test that.)
It's possible that Windows Vista can do better than Ubuntu here, but then you'd have to run Windows Vista and, trust me, you don't want to on the Mini 12. (Our evaluation Mini 12 actually came with Vista; it was achingly slow.)
(There is no power rating for suspend to RAM because as far as I could tell, the Mini 12 (under Ubuntu) didn't support it. The Mini 12 draws no power when suspended to disk or powered off, as you'd expect.)