Squeeze more life out of your mobile device batteries: Alex Slawsby, IDC mobile services group senior analyst, helps you understand your portable power options, and shares tricks for staying up and running longer.

You might not give much thought to the battery powering your PDA, mobile phone, or laptop until it conks out at an inopportune moment--say, when you're talking to an important client on a mobile phone or using your flight time to put the finishing touches on a presentation. Before this happens to you, take the time to learn about the different battery types available, and how to extend the time you spend away from the power outlet.

ADVISOR SPOKE WITH ALEX SLAWSBY, a senior analyst in IDC's Mobile Devices group, to get insight into the state of mobile battery technology, and strategies for extending the life of power resources.

ADVISOR: What are the common types of batteries used in mobile devices today?

SLAWSBY: There are really two main battery types: Nickel-Metal Hydride and Lithium-Ion. Nickel-Metal Hydride solutions have been around for a while and are making their way out now; Lithium-Ion is really the dominate battery technology. And then there's NiCad [Nickel-Cadmium], but those batteries pretty much went out in the 90s.

ADVISOR: Please briefly explain "memory effect"?

SLAWSBY: Memory effect is something that really came out of the NiCad world. Every time one of those batteries was fully charged and then partially discharged, but then recharged from that partially discharged state, the battery would essentially think it was fully charged when it wasn't. Over time, substantial capacity might remain, but overall battery life would be minimal. That was really a characteristic of the NiCad batteries, then less so and semi-solved in Nickel-Metal Hydride batteries.

So they came up with a "refresh" solution that forces a full discharge before a recharge. But, that was a time-consuming process and frustrating for device owners.

The Lithium-Ion solutions don't suffer from memory effect. They also have a greater energy density, which means that in the same volume of battery material, more energy can be stored in Lithium-Ion solutions than in Nickel-Metal Hydride solutions. So therefore, in a laptop, where you have a certain size battery slot, a Nickel-Metal Hydride battery would hold less capacity than a Lithium-Ion battery.

Lithium-Ion batteries were introduced in the 90s and are really the standard today in a broad range of devices--laptops, mobile phones, and PDAs, to name a few. There's a been a lot of continued development through the late 90s and over the past few years because--although there are some alternatives down the road (fuel ceils and the like)--there's still significant development work to be done before mass consumption. Lithium-Ion is really what we have right now.

ADVISOR: How much laptop operating time do users get nowadays from Lithium-Ion batteries?

SLAWSBY: It generally ranges from two to maybe four or five hours.

ADVISOR: Does Intel's Centrino battery-saving technology significantly improve on that?

SLAWSBY: Results vary based upon laptop type and battery size. Some Centrino laptops can last for up to six hours (generally four hours to six hours), so it does offer an improvement. Centrino closely watches the power drain of the component technology within the computer and reduces power demand when the computer doesn't need to run intensive processes.

ADVISOR: What's the maximum operating time you can expect for PDAs and cell phones with modern batteries?

SLAWSBY: That gets to the other angle of power consumption: There s a tremendous amount of effort from the semiconductor folks to improve the power efficiency of the chips, of the hardware itself. Ultimately, battery performance improves extremely slowly. It's not like every year battery capacity doubles. Because of that, mobile phones and PDAs range. You can find Blackberry devices that are built to do the relatively basic function of messaging. They can last multiple weeks on a single charge. But for most mobile phones and PDAs, standby time is anywhere from a day for the most power-hungry devices to a week or two for the most power-efficient.

ADVISOR: Are there background tasks I can switch off, change the display settings, etc. when running my laptop on battery?

SLAWSBY: Sure. Both the Windows and Mac OS are pretty good in terms of power management. But certainly it's critical, if you really want to maintain battery power, to go into the power management settings and set the hard drive to spin down at a certain point. In some cases, it might be three minutes, or a minute. The hard drive's spinning is something that certainly drains battery power.

Some power management solutions let you reduce the level of backlighting, so you can dim that display. Ostensibly, if you're just working in a Word doc, the drive spins only when you save the document. So if you're working on a document and you save every once in a while, that's fine, but the drive doesn't need to be spinning while you're working. Obviously, if you're running applications that are graphically intensive--games, for example--that'll certainly run down the battery life. Watching movies isn't too bad. You're spinning the DVD drive, but it isn't as bad as spinning the hard drive.

Then, if you're really out there, you can try to leverage some kind of RAM disk solution, where you use part of the solid state memory for storage and store your files in it. Obviously, if the computer shuts off, unless you've got software that'll back it up automatically to the hard drive, you'd lose it. But while the computer's running, you could keep saving to RAM and the hard drive never needs to spin. You used to be able to do that on the Mac pretty easily; it was just built in. I haven't done it on Windows. There may be an application out there for that.

Another thing is your page file--make sure you have enough RAM. Windows uses a page file, which essentially uses part of the hard drive as if it were RAM. The more physical RAM you have, the less the page file is important. You can never have enough physical RAM, because then you'll need to use the page file less and less, and that contributes to the hard drive spinning.

SpeedStep [part of the Intel Centrino technology] is something that's really important. It cycles down the processor on newer Windows-lintel-based laptops when you're mobile. For example, I have a 2GHz P4 on my laptop; when I'm running on batteries, it cycles down to 1.2GHz. So if you have a SpeedStep laptop, be sure you've enabled that setting.

ADVISOR: Let's talk about those device features and the repercussions they have for power consumption. What features use the most power?

SLAWSBY: Display technology and backlights are huge. Wireless is huge, especially when you're using wireless and are transmitting [voice or data] over a long period of time. Everyone's looking at hard drives in mobile phones and PDAs. One of the major issues there is the fact that rotational media draws significant power.

The important thing to realize is there's a lot of interest in higher levels of content complexity--games, video playback, .MP3s, etc. With entertainment, multimedia, and gaming content, the better quality it is, the more device-intensive it is. So, power consumption becomes an increasingly serious problem, and the burden lies on the hardware vendors to eke as much efficiency as they can out of their hardware without relying on the battery itself, because batteries just aren't getting any bigger.

EDITOR'S NOTE 

As is standard practice, this interview was edited for clarity, length, and organization. While some of the speaking style was altered to be more readable, every effort was taken to preserve the speakers' meaning.

Power Management Tools

Here are a few tools that can help you track mobile device battery status and extend running time.

Laptop

Power Center, freeware from Tien-Hao, is a battery management program for laptop machines that gives you an estimate of how much longer your battery will run. It recalibrates the estimations with each check and records them to improve the accuracy of future estimates. It works with Windows 2000/Me/98/95.

PassMark Software BatteryMon is a Windows program that lets you monitor laptop computer batteries and uninterruptible power supplies. You can view battery charge/discharge rates in graph form, diagnose problem battery cells, compare performance with expected discharge rates, and see the status of individual battery packs when you're using multiple batteries. You can view statistics such as voltage levels, battery chemistry, serial number, design capacity, charge cycles, and charge rates. BatteryMon works with Windows XP/2000/Me/98.

Palm OS

Batmon, freeware from Shigeru Ikeda, is a standard Palm application that lets you view the current power status of your Palm OS device. You can change battery profile of the device through the scratch pad dialog using a hidden Palm OS shortcut command.

Whizoo BtToggle for Palm OS devices helps you manage power consumption related to Bluetooth connectivity. By controlling the Bluetooth radio's power, you can minimize unsolicited Bluetooth connections and keep unwanted key presses from draining your battery.

Pocket PC

Ra Software ScreenControl switches off the screen on your Pocket PC to save battery power. To turn off the screen, use the shortcut or the hardware key you've set up. You can turn it back on by pressing the Up key on the device.

Birdsoft PocketSysWatch is a Pocket PC/iPaq system tray utility that lets you see how much battery life and memory you have left on your device.