For anyone who uses a mobile phone on a regular basis, it's an all too familiar scenario. In the middle of an important call, the unimaginable happens: that annoying beep, the blinking red light, and your battery is dead. If you're on the phone with a friend, it's annoying; in an emergency, it can be catastrophic.

There are a number of common ways to recharge a phone, of course, including a variety of home and car chargers. But what do you do when you're on the move? For outdoor activities and as a backup in case of an emergency, there aren't many options.

Recently, a number of companies have started to offer more innovative solutions to the power problem, ranging from hand cranks to bicycle-powered dynamos. For inspiration, the inventors looked to the most basic technological needs.

A Battery You Can Crank
In the early '90s, moved by a documentary he'd seen about the spread of AIDS in Africa and the challenges of communicating its dangers in areas that lacked electricity, British inventor Trevor Baylis developed the first windup radio. Using a simple clockwork mechanism, the radio gave 14 minutes of listening time in response to two minutes of winding.

Soon after, entrepreneurs Rory Stear and Chris Staines formed the London-based Freeplay Energy Group (www.freeplay.net) to market Baylis's invention, which became a success worldwide. In 1998, Freeplay added a similarly powered flashlight to their product offering and last year, the company announced the FreeCharge mobile phone charger, developed in partnership with Motorola.

The FreeCharge device is about the same size and shape as an average cellphone, and weighs approximately seven ounces. The unit is priced at $64.95 which, Stear says, is intended to match the price of a long-life battery. "I think this is very well priced for mass market consumption, especially if you think of it as your spare battery that you can crank," he says.

The device is made up of two main components: a base with a hand crank that serves as the generator, and a pod that links the base to the specific model of phone being charged. The base also includes a battery that stores the energy from the hand crank before it's transferred to the phone, enabling the unit itself to store between one and two full charges for a typical cellphone.

Gary Brandt, business director of Motorola's companion products and accessories division, explains that the large-capacity battery proved to be a trade-off in terms of size. "It's been ergonomically designed to fit in an average person's hand, which caused it to be fairly wide," he says. "We decided to fill the cavity with as large a battery as we could, which added some weight."

A Variety of Markets
The most challenging issue in developing FreeCharge, Brandt says, lay in the transfer of power from the charger to the phone. "If you plug a device in that hasn't been designed properly, the phone won't recognize it and will try to shut down," he says. "FreeCharge had to be adapted to three different schemes to work with the overwhelming majority of our product line, and it was a challenge to get all that together."

According to Brandt, similar issues are being examined regarding other devices as Motorola looks for ways to expand the market for FreeCharge beyond their own mobile phone products. "It will work with some of our competitors' phones in the next three to four months," he says. "And we're also looking at adapting it to PDAs and similar devices that require rechargeable batteries."

In marketing FreeCharge, Stear notes that the developing world is the most obvious target. "The explosive growth of digital phones in the developing world is unbelievable," he says. "There are 22-million subscribers on the continent of Africa as we speak, projected to more than double in this year alone. And with only 30% of sub-Saharan Africa being electrified, there's an enormous need for this energy."

Still, as a backup for emergencies, a number of Western users may also be interested in the product. "High-volume users, people who make more than five calls a day, have always had incidents of being out of power on their phones," Stear says. "And conversely, very low users, people who just keep a cellphone for emergencies, really want to be sure they have access to energy at all times."

The best market for these products though, may actually be in outdoor recreation. In the U.S. in particular, the world of boaters, campers, and hikers is ripe for an independent power source: there's a lot to be said for a phone charger you can use in your canoe. "In the U.S., over 40% of families utilize the outdoors a lot, so they're a huge target market to aim toward," Stear says.

The most direct competitor to FreeCharge is the Florida-based AladdinPower (www.aladdinpower.com), which didn't respond to requests for an interview. The AladdinPower charger is similar in many ways to FreeCharge, though it uses a tension-grip hand pump rather than a crank. The device is currently priced at $59.95; the Stepcharger, a similar unit which uses a foot pump, will be released within the next few months.

Bike Power
In the outdoor recreation market, however, both FreeCharge and AladdinPower may face some competition from an unlikely rival: a Swedish startup company called Ikon Global (www.ikonglobal.com). According to company founder Kieron Loy, the inspiration for his Pedal & Power device was similar in many ways to the motivation behind FreeCharge.

"About nine years ago, I was traveling around the world, backpacking here and there," Loy says. "In Thailand, I was in a small village taking photos of a water buffalo in a rice field. I remember seeing a guy on a bicycle cycling along, and it came to me; with all the energy of bicycles and the need to power low-power devices, it was just an obvious marriage of the two."

For years, Loy notes, bike lights have been powered by tiny generators attached to a bicycle's wheels. The wheel spins the rotating head of the generator, which then powers the light. All that was necessary to turn that generator into a power source for devices like mobile phones was a more smoothly controlled flow of DC current.

Pedal & Power consists of three basic parts: a dynamo that attaches to the wheel, a charger unit that sits just in front of the seat, and a universal cellphone holder that attaches to the bike's handlebars. The cellphone then sits in the holder, and connects to the charger through its own cigarette lighter adapter.

At $39.95, Pedal & Power is far cheaper than FreeCharge or AladdinPower, and Loy suggests that the market for the device is strong. "It just encourages more people to get back on their bicycles," he says. "In America, you have something like 50-million regular cyclists; and it's a vast market around the world, with about one-and-a-half-billion cyclists worldwide."

You Need More Things
There's one other motivation behind all these alternative power sources: the endless search for accessories. Freeplay's Stear explains that Motorola's Companion Products and Accessories Division had been very much on the lookout for something unique and different when they came across FreeCharge. "They were really keen to put out accessories that weren't just cases and spare batteries," Stear says.

Motorola's Brandt agrees. "We're trying to do more to enrich the use of cellphones; you need more things," he says. "It's more than just making phone calls: people use them as part of their lives a lot more now. So from an accessory perspective, we're always looking for new products that can allow us to reach out a little bit more and improve the whole mobile phone experience."

Ultimately, though, Brandt suggests that what makes ideas like these so attractive is their surprising simplicity. "When I first looked at this, it just made so much common sense that a product like this was needed," he says. "It's such a simple solution to a complex problem."