Does flash disks increase laptop battery life?

Laptop PCs need longer battery life. I used a flash-disk based laptop for much of the ’90s and loved its 10-hour laptop battery life. You just have so much more freedom when you don’t need to worry about keeping a laptop battery charged.
I’ve been very interested in how flash drives could extend notebook hstnn-ib04 life. Using a Kill-a-watt power meter I ran some experiments with an Intel Core Duo notebook. Power use is a little more complex than I’d thought. Here’s what I found.
Laptop config:
MacBook with the 2 GHz Core Duo,
2 GB RAM,
Intel 950 integrated graphics,
13 inch screen,
8x DVD Drive,
160 GB Western Digital Scorpio 2.5″ 5400 RPM HDD,
Bluetooth,
Wi-FI
One of the nicest things about the hstnn-ub02 MacBook is that disk drive removal is easy (see the 1 minute video here). I ran the tests with the internal Scorpio drive removed and ran the MacBook off an externally powered FireWire drive.
InstrumentationIn addition to the Kill-a-watt power meter, which sits between the wall power and the MacBook’s power adapter, I also used the most excellent open source MenuMeters utility. MM shows CPU, memory, disk and network usage,hp pavilion zv6000 battery, typically sampled over a user-selectable 1-2 second period…
The TestsI booted the system while video taping power usage with both the internal and external disks. I also ran a disk defragmentation tool,hp presario r3000 battery, the estimable iDefrag to create heavy disk I/O.
Since I had the system up, I also checked some of the other subsystems. Display power consumption was measured with the display off and at minimum and maximum brightness. Optical drive consumption was checked by watching a DVD and ripping a CD. Idle power consumption with the screen off and CPU at 3-4% was also checked. I even removed a 1 GB SO-DIMM.hp pavilion zv5000 battery.
The ResultsThe surprise is that you can’t just turn features on and off to judge power use. For example, performing I/O is a CPU involving business whether to disk or over Wi-Fi. In my defrag workload the CPU utilization ran from 80-95% on both cores,dell latitude d820 battery,dell latitude d830 battery for an 8 watt hit - almost 3x of a busy disk…