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The overwhelming majority of contemporary watches are electronic. For many years now they’ve required batteries to power their functions.

But watch batteries can be expensive and fail at the worst time. You may buy a watch for $20 and spend another $20 on batteries over its wearable lifetime. Batteries can also, in rare cases, corrode and ruin your watch.

Battery-less watches to the rescue!

Seiko’s Kinetic, and other models, feature a mechanism that allows you to power an electronic watch without a battery. Similar mechanisms, such as so-called self-winding watches, have been around for decades actually.

The first such mechanism was designed in the 18th century, and the modern type was patented in 1923.

Shaking the watch, or movement from normal wearing, caused a small, mechanical weight to wind a spring. But those were strictly for watches with mechanical timekeeping devices – springs, used to power the oscillator or balance wheel.

The newer technology is similar in that it still uses mechanical motion, but in this case – like a miniature dynamo – it uses that movement to generate electricity that is then stored in a capacitor.

Capacitors are tiny electronic devices that store current, but for much shorter periods than batteries. Also, unlike batteries, they don’t generate electricity on their own.

Other powering technology has been around for a long time. Solar powered watches, for example, have been common for over 20 years.

But solar watches, though they don’t require an outside power source, still have a battery. In that case, the watch has a photo-receptor cell and associated circuit that recharge the onboard battery.

A solar-powered watch without a battery (with rare exceptions) would run down quickly without a long-term storage feature, such as a battery.

The exceptions are very expensive, high-end capacitors used for space applications and other specialized purposes. Citizen, for example, has a range of solar-powered models, but they have batteries.

Some recent designs even use the temperature difference between the skin and air to create a current. That current is used to power the watch.

In the electronic, battery-less watch the timing mechanism is essentially the same as any other electronic watch. The current powers a quartz timing mechanism, which vibrates when a voltage is applied. A circuit senses that vibration and turns the oscillations into mechanical movement of hands or changes an LCD display.

Whether these are the wave of the future or not depends more on market forces than technology. Certainly, having a watch that never requires replacing the battery is a value.

But there are lithium-iodine batteries in use in some applications that will now last for 20 years. That makes widespread adoption of the technology as much a matter of advertising as it is a technical advantage.

That said, the idea itself is very cool. For those gadget freaks it offers another advantage in that these models offer several different ways of monitoring the remaining power.

Capacitors naturally ‘bleed off’ stored current over time, unless recharged. That indicator can itself be an attractive feature, for those who like to push a button and see ‘battery life’ when there is, in fact, no battery.

The ‘coolness factor’ should never be discounted when looking for a watch. After all, you don’t really need another timepiece just to tell the current time, do you?