Don’t Stress About Smartwatch Battery Life—It’s A 500 Year Old Problem

A hot new rumor about the AppleWatch’s supposed working battery life of 19 hours has sparked a lot of debate both pro- and anti-Apple, inevitably. But here’s an idea to help view the watch’s power consumption in context: It’s a centuries old technology battle.

We know the Apple Watch is coming in April. We know it’s contentious, and could revolutionize the wearable tech world (if Apple’s as successful in stamping its mark on this market the same way it did with the tablet, smartphone, MP3 player and laptop and desktop computing ones). But the “leak” via 9to5Mac of what’s alleged to be Apple’s battery life performance targets last week has added a whole new spin to the rumour mills, and delighted both Apple fans and critics alike.

Fans are happy because 19 hours of “mixed” use, with the watch mainly on standby and in typical-to-heavy use for only about 2.5 to 3.5 hours a day is actually quite generous—it means a nightly charge during a typical 8-hours of bed time is going to be more than enough. The news has also delighted Apple detractors because the 3-hour-ish figure sounds a little small compared to other devices like the Pebble smartwatch which can last around a week between charges. It sounds even more odd when compared to more sports-orientated wearables which can go for very long periods between charges even though they’re more frequently in use.

Here’s the thing: This whole debate is silly.

19 hours sounds very reasonable. Picture yourself looking at and interacting with your watch for 2–3 seconds at a time as you read notifications, with the occasional 10–20 seconds used to respond to something like a tweet or text message. Add in less frequent longer interactions lasting a few minutes (like making a phone call or playing a game—even though we don’t know exactly how much game play Apple will ultimately allow in watch apps) and then that 3-hour “heavy” use window looks quite generous. You wouldn’t want to stare at such a small screen for much longer each day anyway. It’s also a first generation device, and Apple’s proven advanced product development techniques will certainly deliver more power in version 2 (and yes…I know, the “money grabbing” upgrade/renew cycle is a whole other tiresome debate).

And look at it like this: Ever since clockmakers worked out how to make clocks portable there was an almost continuous technological struggle between how much “battery life” and capability the devices had. This affected the first pocket watches and wristwatches, and pretty much every watch ever since.

Portable clocks began to be common in the 1400s in Europe (ever thought about where the name “carriage clock” came from?). They got more reliable and shrank in size as clockmakers worked on improving their accuracy and how much power could be gleaned from a wound spring. Of course, spring driven clockwork was preceded by many hundreds of years of other less reliable and less power-dense energy storage systems like falling weights, but let’s keep this about portable clocks.

Eventually after about a hundred years portable clocks could be carried on the person, as the revolutionary “watch.” For the first time people could reliably carry the time around with them, instead of having to guess, ask other people or use publicly-viewable clocks to know the time. And you can imagine you had to pay a hefty price to be part of this new revolution.

But the earliest watches lacked a minute hand because of the need to pack so much technology in to power them and also to drive the “display.” This wasn’t a problem since the accuracy was so poor they drifted off accurate timekeeping by up to hours every day! Their tiny springs and inefficient clockwork also meant they didn’t store much power. Thus they needed winding very regularly—at first with a key, just like traditional grandfather clocks and whatnot, which is self-evidently inconvenient.

Wrist and pocket watches (with wristwatches being mainly worn by women at first) slowly advanced as breakthroughs in clockwork technology improved the movement’s accuracy and how much winding they needed. The second hand arrived around 1700, as a result of improved accuracy and power. And over the next several centuries clockmakers worked to develop reliable spring-powered wristwatches that could last nearly two days between winding.

As watches were capable of doing more as their design evolved, the movement placed more demands on the power source—a wound spring—demanding developments that made the watches more energy efficient (like frictionless jewelled bearings) and advances in spring technology. The first self-winding mechanism was invented in 1770, effectively negating most energy issues, but it took many advances and inventions until the early 20th Century for the first successful watch to actually go on sale in Britain with an automatic self-winding system.

That’s about 500 years of development for clockwork watches. But they of course evolved throughout the 20th Century with improvements in power consumption, accuracy and capability. Every step was a battle between the features the watch needed to have and the power and tech that could be squeezed inside.

Then a paradigm shift happened in the tech, and the digital electronic watch arrived in 1972, thanks to advances in LED technology, quartz timing and microelectronics. The Pulsar watch was the first example, and it had an 18 carat gold case and cost over $2000 at the time—equating to well over $10,000 in today’s money.

The Pulsar watch and other early digital watches like the famous revolutionary-but-flopped 1975 Black Watch from Sinclair (available as an £18 kit) one were very futuristic, but the display and timing electronics gulped down so much electrical power from the tiny batteries that could fit inside the case that they didn’t display the time all the, er, time. You had to push a button to turn the red LEDs on. In many ways this made them as limited, if revolutionary, as the first pocket watches with no minute hands.

Of course over the next 20-plus years the silicon chip revolution and evolution, happening in parallel with similarly fast-paced development in compact battery technology, led to more powerful and more reliable digital watches that used LCD displays. Tech advances even led to added features (“complications” in traditional watchmaking speak) like stopwatch timing, alarms and calculators. Water-resistance and then waterproofing arrived over time too. And the price and reliability of digital watches dropped and went up dramatically as each advance was made. But each step was a delicate balance between the capabilities of the watch and how much electronic smarts, and importantly, battery power, could be squeezed inside.

And now the next paradigm shift is upon us. The modern smartwatch, let’s say exemplified by the Apple Watch (which is, let’s face it, going to be the smartwatch to beat), is effectively an ultramobile computer with processing power that would’ve boggled the minds of 1970s-era watchmakers, and seemed like witchcraft to those engineers who crafted the earliest portable clocks. There have been many “smart” watches that hit the shelves before the Apple Watch, yes, but read on to see why today’s smartwatch means so much more in terms of influence and capabilty than these early examples.

The smartwatch of 2015 does so much more than merely tell the time. It sports a touchscreen display, sensor array and wireless tech.

Inside its processor, wireless system and screen place a huge burden on battery tech that has to fit into more or less the same size case as the first wristwatches of 500 years ago. Indeed the S1 processor inside the AppleWatch is rumored to be about as powerful as the A5 chip found inside the iPhone 4S and second-generation iPad. In other words, the roughly 2cm-across Apple Watch is a mobile computer that, in certain ways, is more powerful than the very first iPad—a revolutionary tablet computer that had a 25-cm screen and huge battery. Also inside the AppleWatch case will be Bluetooth circuitry, motion sensors and Apple’s rather interesting health sensor package that measures your pulse using infrared and visible light. Add in a vibrator for haptic feedback and that’s a heck of a lot of chippery that’s burning power from a battery that’s going to be much less than 2cm across.

In context compared to early wristwatches the Apple Watch, Pebble or any of Samsung’s slightly scrappy attempts at making a wrist-worn wearable are tiny pieces of magic. Enjoy them, learn to live with their quirks and occasional inconveniences, and don’t complain. Next year’s ones will be better.


Imagery from Apple, and Flickr users Joe Haupt, Bob Mckenzy, Liz, Steve Krave, PhotoAtelier