Prior to the final release of Microsoft Windows 7, there some question as to what the new operating system would do for battery life on laptops. At that time, I felt it was too early to make any judgments, simply because final hardware drivers and power management utilities weren’t available. Now that Windows 7 is available, most vendors have provided software updates, so it’s a good time to check in on this. I spent yesterday running a Battery Eater test on my Toshiba NB205 netbook and then re-ran the test today. I have the device setup for dual booting between Windows XP and Windows 7, so it’s pretty easy to run the test. Battery Eater stresses out the device under test to provide the minimum runtime you can expect, not the maximum. I tried to setup the environments as equal as possible in what I consider a reasonable “real world” situation: screen brightness at 40%, Wi-Fi on and all power management features disabled. I’m a little surprised at the results.
Yesterday’s test with Windows XP yielded a minimum runtime of 5 hours and 5o minutes. I get around 8 hours of usage with proper power management and basic web usage, so the Battery Eater test seems about right. Today’s test with Windows 7 was about 10% shorter, however — the netbook battery died off at 5 hours and 15 minutes.
I’m scratching my head a little over this because I had read about a similar test using the ASUS Eee PC 1008. In that test, Windows XP ran for 5 hours and 3 minutes on a single charge. The same device with Windows 7 ran for more than an hour longer — 6 hours and 7 minutes. Since the Eee PC 1008 and the Toshiba NB205 are essentially built from the same hardware, the only conclusion I’ve drawn is from the one variable: device manufacturer software.
When I got the latest Toshiba Power Management utility for Windows 7 last week, I was leery that it wasn’t quite the same as it was for Windows XP. For starters, there isn’t a Toshiba application or GUI for the power management — it’s simply integrated within the Windows 7 Power Management applet in the Control Panel. And even there, I only see one bit of evidence that there’s any Toshiba optimizations.
The other possibility here is that the ASUS Eee PC test was flawed. I’m not saying it was, but it was performed with two different netbooks — one had a brand new battery while the other had been through a half-dozen charge cycles. Even with the different physical hardware, I don’t think the test could be skewed by 20%, but it’s possible.
Just for kicks, I think I’m going to re-run the test one last time once the battery is fully charged again. I was running all of the Aero bits under Windows 7, so I’m wondering how much battery life I can gain by turning those features off. If I find that the battery life gain is 10% or more, I’ll report back in, because I think that’s significant.