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Tools turn laptop into power source for handheld devices

By Glenn Fleishman
Special to The Seattle Times

	The Kensington travel adapter can be used in cars and airplanes.
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A few years ago, our cellphone batteries would poop out after an hour of talking or a day of standby, and our laptops could barely play CDs and handle word processing for two hours.

Today's digital devices are much more miserly power users, but digital road warriors are still stuck on every trip carrying several power bricks — those half-pound or heavier power adapters unique to each device that plug into wall outlets.

Even as we cut phone cords and connection cables by using cellphones, Bluetooth and Wi-Fi, we're still tangled in power cords. (Wireless devices don't help; they need to be recharged because they suck down power constantly when in use.)

There's a solution, one that requires switching from bricks to USB (Universal Serial Bus) and similar cables that can trickle power to such devices as cellphones, personal digital assistants and MP3 players.

This approach allows you to centralize your power-supply needs in your laptop, reducing the clutter and confusion of dealing with numerous cables and differing connections.

Let's look at the options for charging via USB and FireWire, and the options that can help you keep a laptop battery or two charged and ready for its trickling duties.

Universal power

The USB port on portable computers sold since the late 1990s isn't just for exchanging data. It also aids sending a nominal electrical charge to power sensors or controls on keyboards, mice and even scanners or digital cameras.

With the right adapter, you can even plug in devices that don't have USB connectors — such as cellphones — and slowly charge them from the laptop.

The only drawback of USB charging is that if you leave devices plugged in when your laptop is fully powered down, not just in sleep or standby mode, the computer's battery can drain the peripheral's power — a reverse flow of sorts.

American Power Conversion (APC), a veteran supplier of battery-backup systems, also makes some of the highest-quality USB charger cables. It has cellphone cables at $15 to $20 each for a large number of models. PDA adapters for Palm and Pocket PC models also support synchronization; they're $20 each.

Keyspan offers similar adapters in its Zip-Linq series of retractable cables (www.keyspan.com/products/homepage-Cables.spml). The retractable feature keeps the adapters neatly tucked away when not in use. The cellphone adapters cost slightly more and PDA adapters slightly less than APC models.

If you own an Apple iPod, you can charge it using its docking cable via a FireWire port on a Mac or certain IEEE 1394 ports on a PC. (Some FireWirelike ports, such as Sony's i.Link version, don't always provide power, only data transfer.)

Many competing MP3 players have to be plugged into the wall, however. For instance, the iRiver H series, similar to the iPod, states categorically that a laptop couldn't provide enough charge.

Digital cameras are a tougher nut to crack. Many have no charging circuitry at all, requiring you to carry an external battery charger, not just a cable. I found only a generic product at a single online store that offers support for supplying power over USB to cameras with DC inputs (www.buynshop.com/productinfophp3/DC-UN-CHTA).

Keeping the battery charged

Because your goal is keeping the laptop battery charged, you might set your sights wider than using just a regular power cord.

The vast majority of laptops use variable power systems that allow you to use a single AC adapter with different plug tips for every country in the world. For instance, Laptops for Less offers a $25 kit with outlet plugs for Europe, Asia and Australia (www.dcacpowerinverter.com/).

Less exotically, if you find yourself spending plenty of time in a car, you can use an auto inverter to convert the voltage from the cigarette lighter (or "power adapter" in politically correct modern cars) into a normal 110-volt plug.

Auto inverters cost $50 to $100, depending on the overall wattage required — most laptops need 75 to 120 watts — as well as safety features and the number of AC outlets (typically one or two).

Some power kits for specific notebooks come with interchangeable inverter options. For instance, Kensington offers an adapter AC, auto and airline power adapters (www.kensington.com/html/1961.html). ND Dimension has an inverter with a USB jack at the end for charging individual USB devices, as well (www.nd-dimension.com).

If you're a frequent flier, the mention of charging your laptop on a plane sounds immediately interesting. But airplane power outlets are typically found only in business and first class, and then only on certain planes.

An easier option may be a second battery, which often costs $100 to $200, depending on your laptop model. Older laptops with two to three hours of battery life beg for a second complement. Newer Centrino laptops can top five hours on a single charge, but USB power adapters will drain that battery faster.

If you spend quite a while away from a power outlet, you could consider a special form of external battery from Valence (www.valence.com/ncharge1.asp). The N-Charge system offers five or 10 additional hours of use on a typical laptop for $200 (1.5 to 1.75 lbs) or $300 (about 3 lbs.), respectively.

The N-Charge is shipped with a notebook adapter for your model and can also have an optional cell or PDA charger. The current series is thinner but about the same width and length as a laptop; a newer series is slightly smaller and lighter but isn't yet shipping.

Bag of all power

	The APC TravelPower case

For the ultimate in portability, you might consider the APC TravelPower Case ($100 to $180), which comes in several models, including a backpack version, and includes a unique power adapter. The bag has pockets designed for different-sized peripherals and the adapter.

The adapter's unique feature is a single USB port on the side. It also includes an adapter that turns the single port into two USB ports. The notebook cables are fed through a grommeted hole in the outer pocket through to the laptop compartment in the center. You attach the appropriate tip from a bag of supplied adapters onto the end of the power adapter. (Oddly, it doesn't have an Apple PowerBook adapter despite Apple's large laptop sales.)

The USB adapter and splitter are connected to separately ordered cables that can be cleanly stored next to each peripheral. The power cord ends with a special plug onto which you connect the included AC, airline or auto tips; an optional international kit fits onto the same plug.

I spent time with the 1300B, one of the larger of the notebook cases, and it had a number of flaws, including a design that left the bag unbalanced once the laptop and power brick were in place, a laptop compartment that could barely fit a 15-inch eMachines laptop with cinema proportions, and an adapter that was too hot to touch when in use.

The bag's manual includes a warning sticker that notes the adapter "can become hot to the touch. Allow the adapter to cool before handling." It also instructs you to affix the sticker onto the adapter.

Also, the adapter can't reliably charge increasingly available 90-watt or higher laptops while the laptop is in use if the battery is significantly run down. You also have to turn a dial on to choose the voltage of your particular model to avoid damage to the adapter and your computer.

While the adapter's unique USB connector reduces clutter, its design problems, coupled with worse issues with the bag itself, make it a poor traveling companion.

Charge ahead

Perhaps the father of modern alternating current electricity, Nikola Tesla, will someday see his dream of wireless power come true. Until those days, we digital road warriors live half in a DC world, half in an AC world.

The laptop-charging approach can at least drop a few pounds from your bag and increase the chance that your devices are ever-ready.

Glenn Fleishman writes the Practical Mac column in Personal Technology.

Copyright © 2004 The Seattle Times Company