Is one method better than the other, or just a matter of preference? On the one hand, kinetic energy generation requires movement, whereas, a light-powered watch, such as a Citizen Eco-Drive model, is obviously more passive, and thus requires fewer moving parts.
Fewer parts is always better in terms of long-term reliability, however in the case of a watch it's likely more of a moot point since analog watches are already composed of a zillion parts, so what real difference will a few more make.
Some background on how both these power systems function is likely in order before drilling down to deciding which is best. Obviously, this discussion has nothing to do with watches requiring daily winding either.
Seiko pioneered the self-winding watch back in 1980. They came up with a way to translate the motion of the wearers arm movements into the mechanical energy necessary to wind the watches mainspring. The fancy word kinetic simply means motion-generated mechanical energy.
The way they do it is by letting arm motion swing this rather odd-shaped rotor, weighted heavily on one side, around a winding mechanism that, with the use of specialized reversed gearing, will only move in one direction. The result is a wound mainspring.
This in itself will keep the watch wound as long as it's worn and thus receiving kinetic energy input. However, when left off the arm for a day or two, it would stop. This is especially germane since I'm focusing on dive watches, which may or may not be worn as a regular everyday watch.
To solve this problem, Seiko added a battery to store the excess kinetic energy. Now, assuming the battery is fully charged, the watch can lie still for years and still not require winding.
Instead of kinetic energy, Citizen developed a way to utilize light as a power source. And it doesn't have to be sunlight - any light source will do fine.
On the faces of their Eco-Drive watches, Citizen places tiny solar cells that transform light into electrical energy. This energy is then collected and stored in energy cells, like a battery, that will supply power for extended periods, even without light.
Again, since were talking about dive watches, this is particularly useful for someone who only uses the watch for diving, versus wearing it everyday. By storing up energy for later use, these watches could be left idle for extended periods, and still show the correct time.
In fact, many new models, both kinetic and solar, have a hibernation mode where after sensing no movement for an extended period, the hands and dial functions stop moving to save energy. But the quartz movement continues to keep the correct time, so that once the watch is moved again, they sense that and reset to current.
Battery technology has come quite a ways too, so it's gotten to the point where this storage cell or battery, would last past the lifetime of the wearer. That means the battery would never need replacing, making these watches super environmentally friendly.
So which is best? Well, if the watch is worn with any amount of regularity, it appears to not really matter. Either energy source will work fine. You can also see that either type watch can be left idle for various times ranging from months to years, and continue to keep correct time.
I suppose if one left the Citizen solar watch in a drawer long enough, it would finally stop from lack of light, but then so would a Seiko kinetic watch from lack of movement.
At the end of the day, it's sort of illogical to buy any watch and leave lying around for years, so the answer has to be that both energy generation techniques work well, and it simply becomes a matter of personal preference.
| Price : 
