3 ms·
> Could some well-placed solar cell on the watch do the trick (think calculators). My Casio watch has two tiny solar panels built into its face. According to t
by kijin 13y ago
> Could some well-placed solar cell on the watch do the trick (think calculators).
My Casio watch has two tiny solar panels built into its face. According to the manual, 5 minutes of sunlight each day (or a few hours of indoor lighting) is enough to compensate for normal use, and the battery will last 6 months even without any sunlight.
I've had the Casio for 9 years now. It still works fine, and I've never had to manually charge or replace the battery. The battery does get a bit low in the winter when the watch spends a lot of time covered by thick clothing, but that problem is easily fixed by leaving the watch in the sunlight for a few hours when spring comes.
Sure, it's not "smart", but it can display the time in several different timezones, act as a stopwatch, and even has a button that lights up the display at night (which will probably drain the battery faster). All running off of two solar panels the size of the nail on your pinky.
- darkmighty 13y agoThe energy requirements are magnitudes away, you could never do that for a "smart" device. By the way, we also have the much older self-winding mechanical watches which harvest body movement; those are pretty reliable and can also run indefinitely without maintenance.
- kijin 13y ago> you could never do that for a "smart" device. That sounds overly pessimistic. Computing power per watt has improved by several orders of magnitude over the last couple of decades already. Combined with more energy-efficient displays (anyone wants to improve on e-ink?), who knows what we could pull off 5-10 years from now, even without a significant change in battery capacities?
- marcosdumay 13y agoWell, I opened a calculator to prove you wrong, and guess what? 300K * k * 1GHz = ~4pW Or, in other words, you are right, we can in theory reduce the power consumption of our computers so much that a current watch will last for a lifetime.
- darkmighty 13y agoComputing power is not the limiting factor. Far more relevant are the display, which has efficiency physically limited by its luminosity -- and we're less than a magnitude away from the limit. Even disregarding that for e-ink, there's the radio, which is limited by the channel capacity, from which I'd say we're also less than a magnitude away for isotropic radiation.
- eru 13y agoE-ink is fun, but I'm not sure it's the right thing to do for a watch. Doesn't it have exactly the wrong trade-offs?