Seiko started the trend two years ago with the splashy and successful introduction of its Kinetic series of watches. Last year, the Swiss watch giant SMH bought out its own battery-less technology, called Autoquartz, in the Tissot brand. SMH brands Omega and Longines followed this year with their own battery-less models, while Seiko has incorporated Kinetic movements into its new Arctura line. What's gotten into these brands? Read on.

What are the benefits of a battery-less watch?

Will battery-less watches make battery-powered watches obsolete?

1. What are the benefits of a battery-less watch?

- The wearer need not worry about any environmental pollution that could be caused by disposal of used batteries.

2. How do battery-less watches work?

From this point on, the battery-less watch functions as a normal quartz watch does: the electricity is transmitted to an integrated circuit, which keeps the quartz crystal oscillating at 32,768 Hertz. The integrated circuit sends impulses at one-second intervals to the stepping motor, which powers the gear train, which moves the watch's hands.

3. Who makes battery-less watches?

The major players are Seiko and SMH. Other companies are also experimenting with battery-less technology. Citizen makes a battery-less movement which it sells to Festina for use in its watches, but so far hasn't introduced it into the Citizen brand.

4. Automatic, or self-winding watches are also powered by rotors that turn when the wearer moves his or her arm. Are they the same as the battery-less watches you're talking about?

No. The terms "automatic" and "self-winding" refer to mechanical watches powered by a mainspring (not electricity, as in the new battery-less watches) and using an oscillating balance wheel (rather than a vibrating quartz crystal) to measure time. The only similarity between automatic watches and watches like Seiko's Kinetic or the Omega-matic is the rotating weight that creates the energy to make the movement work.

5. Do all battery-less watches work the same way?

Basically. There are, of course, some variations in the technology used by the different companies. (Seiko, for example, filed 50 patents for its Kinetic movements). The basic principle, thought, is the same: an oscillating weight generates electrical power which is stored and released gradually to power the movement.

6. Don't solar watches such as Citizen's Eco-Drive models also fall into the "battery-less" category?

Not really. It's true these watches don't need to have their batteries replaced ( they are continuously recharged by light), but they do have batteries.

7. Are battery-less watches as accurate as battery-powered ones?

Yes. Both use a quartz crystal as an oscillator, and it is the type of oscillator used that determines a watch's accuracy (in a mechanical watch the balance wheel serves as the oscillator).

8. Since the battery-less watch is powered by the wearer's arm, won't it stop running as soon as the watch is removed?

Companies are working on ways to increase the length of time battery-less watches will run without being moved. Seiko has just introduced a Kinetic movement called the 1M which it claims will run for three months.

9. Can the wearer tell how long the watch will run once it is taken off?

Some watches also have a warning system to alert the wearer that the power is running low. In Seiko Kinetic models, for example, the seconds hand moves in a jerking motion at two-second intervals to indicate that the watch has only a few hours' worth of power remaining.

10. How can the wearer get the watch running again if it runs out of power while it's not being worn?

You can start a battery-less watch by moving it vigorously. This action gets the rotor spinning, generating electrical energy. Once you've done so, the ordinary motion of your arm will be enough to keep the watch working. Manufacturers have also deviced other ways to start the movement once it has run out of power. The Omega-matic, for example, can be repowered by winding the crown, which generates electricity.

  11. Will battery-less watches make battery-powered watches obsolete?

Proponents of battery-less watches cite Seiko's success with Kinetic as a reason to expect battery-less watch to one day eclipse battery-powered ones. Skeptics point to ever-longer battery life -- some lithium-iodine batteries last 20 years-- when they question whether the advantages now offered by battery-less technology will one day become negligible.

Watch crystals

Watch care and handling

Subdials

Titanium

Light-powered watches

Automatic watches

Chronometers

Battery-less watches