Power Adapters for Travel and Road Trips

Besides data input, power issues are another chief issue for PDA owners. If you use your PDA extensively, you need to recharge it often, not always a convenient option. Fortunately, there are a number of new products that make it easy to recharge your PDA while you're out and about.

When you're shopping for batteries and adapters, it's important that you get the correct voltage for your device. If you select an adapter that has too high a voltage output, you will damage your PDA, perhaps even destroy it. Most PDAs use five volts (5V) or less. Power input as high as 7V can short them out. To be safe, purchase adapters and chargers marketed specifically for the make and model of your product.

When you look at batteries and chargers, you'll see them rated with the acronym mAh, which stands for milliampere hour, or Ah, representing a 1000th of an ampere hour. This is a measurement of the charge that a battery will hold and how long a device can run off it. If you know how much energy your device uses in milliamperes, you can figure out how long it will run off a single charge based on the mAh rating of the battery. The average PDA battery is around 700-900 mAh and lasts a few hours.

One of the big hassles for PDA owners has to pack the PDA's cradle for recharging and synching. This just adds to the list of peripherals that you have to schlep around with you when you travel. Manufacturers have solved this with several new adapters that allow you to charge and synch a PDA using a laptop or desktop's USB port without a cradle.

You can combine this type of cable with other adapters to allow you to recharge from a wall outlet or a car's cigarette lighter. This means no longer having to carry your PDA's cradle just to recharge it. The small size of these cables makes them convenient to carry.

If you don't have access to an outlet, either in a car or building, or to a USB port on a computer, there are some products that will still enable you to charge your PDA. These products are all portable and will get the job done in a pinch.

The first of these alternatives is an instant-charger or an air-powered charger. These devices use a zinc-air cell that produces electricity when exposed to air. Typically these devices can charge a cell phone or PDA up to three times before being disposed of. They cost around $13 and replacement cartridges sell for about $10 each.

Another alternative is using an adapter that allows you to use AAA batteries to recharge your PDA. Several of these are available on the market. Each device has a battery compartment that holds four AAA batteries and an adapter that attaches to your PDA. When selecting one of these devices, make sure it has a voltage reduction circuit (VRC) that regulates the electrical output to ensure that the batteries do not damage your PDA.

The final alternative is solar power. There are portable solar devices available for PDAs and cell phones that allow you to charge your phone wherever you have access to sunlight. These devices fold down to a size that is easy to transport. If you're visiting a sunny climate, like Southern California or Africa, this may be a good way to recharge your PDA when you're on the road.

There are some interesting future power sources in development. While some of them may never become viable consumer products, a couple of them are sure to wind up in commercial products someday.

The loudest industry buzz -concerns fuel cells. These are self-contained devices, similar to batteries, that produce electricity from hydrogen and oxygen (water is the waste product). Toshiba and NEC are prototyping a fuel cell-powered laptop.

Researchers at Birmingham University in the U.K. have produced micro-engines smaller than a fingernail that can run on lighter fluid. One of these tiny engines produces almost 700 times more power than a similar-sized battery and only needs refueling about once every two years. Researchers are predicting that these will replace batteries in portable devices by 2010.

Don't hold your breath. We still don't have holographic data crystals, which were supposed to replace hard disks within five years (a claim almost eight years old now) or the flying cars that science promised when I was a kid.