Battery Talk

Anyone who uses a laptop on an airplane would love a single battery to last through a trans-American flight. Now researchers at Intel believe that they can double a laptop’s battery life without changing the laptop battery itself. Instead, they would optimize power management–system wide–of the operating system, screen, mouse, chips inside the motherboard, and devices attached to USB ports.

Power bars: Intel Research engineers yesterday showed off prototype methods for system-wide laptop power savings. Using the current implementation, average power consumption of a laptop can be reduced from 6.23 to 4.02 watts. The researchers believe that the approach has the capacity to slash up to 50 percent of laptop power consumption.aspire 3000 battery,aspire 3030 battery

To be sure, manufacturers and researchers have been exploring piecemeal ways to make portable computers more energy efficient. Operating systems are designed to deploy power-saving screen savers and put an entire system to sleep if its owner hasn’t used it after a while. And Intel’s forthcoming Atom, a microprocessor for mobile Internet devices, can be put to sleep at up to six different levels, depending on the types of tasks that it needs to do.

But the problem with these approaches is that they’re not coordinated across the entire device. Intel’s prototype power-management system is aware of the power that’s used by all parts of a laptop, as well as the power requirements of a person’s activity, and it shuts down operations accordingly, says Greg Allison, business development manager. The project, called advanced platform power management, was demonstrated on Wednesday at an Intel event in Mountain View, CA.(XPS m1210 battery, vgp-bps9)

Allison gives this example: today, when a person reads a static e-mail, the screen still refreshes 60 times a second, and peripherals such as the keyboard, mouse, and USB devices drain battery power while awaiting instructions. “We’re burning energy even when we don’t need to,” Allison says. In this situation, Intel’s system would save power by essentially taking a snapshot of the screen that a person is reading and saving it to a buffer memory. So instead of refreshing, the screen would maintain an image until a person tapped a button on the keyboard or moved the mouse (the keyboard and mouse would also stay asleep until activated).

All the while, the operating system will be monitoring use of other applications, restricting operations to those that aren’t being actively used. And if there are any devices plugged into a USB port, such as a flash-memory stick, the system would put them to sleep. At the same time, explains Allison, energy-monitoring circuits on Intel chips will put unnecessary parts of the microprocessor to sleep. It takes 50 milliseconds for the entire system to spring to life, he says, a length of time imperceptible to the user.

Intel isn’t the first to think of the idea of integrating power-saving technology throughout a device. One Laptop per Child (OLPC), the nonprofit that builds inexpensive, rugged laptops meant for children in the developing world, set the standard with a gadget that consumes one-tenth of the power of a conventional laptop–XPS M1330 Battery,aspire 3000 battery. Granted, OLPC’s laptop doesn’t have the capabilities of consumer machines, but it does show what is technically achievable.

There are definitely advantages to this systemic approach, says Seth Sanders, a professor of electrical engineering and computer science at the University of California, Berkeley. “Comprehensively looking through the system at all of the different pieces that are cycling unnecessarily provides an opportunity [for power savings],” he says.

Allison says that the company is already talking with operating-system vendors to explore what it would take to integrate this approach into software. And as a major contributor to the new USB 3.0 standards, Intel will have some say in how much power forthcoming USB devices will use. In addition, Allison says, the company is trying to secure deals with display and hardware vendors. “This won’t happen in the next three years,” he says. But he suspects that pieces of the new power-management system will find their way into laptops within five years.

On Sunday night, 60 Minutes reran a segment on the OLPC (One Laptop Per Child) project originally broadcast in May. I missed it the first time and never got around to watching it online (in Windows video format here, for example; there’s a full transcript on olpctalks.com).

Hearing OLPC representative Walter Bender repeat the claim of “10 or 12 hours” of laptop battery life “with heavy use” reminded me of an open question from the last few times I blogged about the OLPC project. What is the battery life of this machine, really?

Back on July 21, the News page for the OLPC wiki (archived here) said this:

We ran battery-life tests on 75 B4 laptops: results will be reported on the OLPC wiki this week.
But I looked around on the wiki during that week and didn’t see anything.

So while Andy Rooney was blathering on about kitchen gadgets he doesn’t use, I started looking around again, and I finally found results. It was a roundabout search. The OLPC wiki’s own search engine can’t look for multiword strings, and Googling the site produced no results for “xps m1330 battery testing,” but “battery test” gave me a page of test results without any explanation.

That led me to a bug report on the OLPC developer site and an explanation of the results back on the wiki.

As it turns out, battery life is not very good. The best of the NiMH (nickel-metal hydride) batteries produced a little over 4 hours of operation. Of the two brands of lithium-ion laptop batteries(dell xps m1330 battery,xps m1210 battery) tested, one was about the same as the NiMH batteries; the other ran for a little over 5 hours. (Some of the NiMH batteries died after only a few minutes, but the bug report explains this away as a firmware problem.)

And this was with the machine idling–running nothing at all. Under “heavy use” it’s likely the battery life will be less than two-thirds of these figures; maybe half or less.

I am certain that xps m1330 battery life will improve over time as the software and hardware are tuned, but these numbers make it pretty clear that the claim of “10 to 12 hours” is no longer within reach. That’s disappointing. To me, this means that much of the long-term promise of the OLPC project can’t be achieved until the next major revision of the platform.