Can the Next Apple Watch Be Any Thinner?

| Analysis

The current Apple Watch contains a 205 mAh battery that takes up about two-thirds of the area and about half thickness of the case. Given that customers would like to see the Apple Watch's battery last longer and yet be faster, what are the prospects for shaving some battery thickness and making the Apple Watch thinner?

Image credit: Apple

In an informal discussion, without delving into exotic approaches, there are at least four things Apple can do to give the Apple Watch, version 2, a longer battery life—in the hopes of making the watch thinner.

  1. Decrease the power required by the SoC and OLED display.
  2. Make the onboard software more power efficient.
  3. Make key components smaller and make the battery larger in area.
  4. Improve the battery design so that is has more milliAmp-hours per unit volume.

Unfortunately, despite heavy R&D, battery technology doesn't improve dramatically from year to year. Perhaps 10 percent. For example, one clever thing Apple did with the 2015 MacBook was to change the battery design to be more conformal. That is, fit into all the nooks and crannies of the case. That adds capacity without any new battery technology required.

Another factor in the design is the extent to which Apple can further miniaturize and reduce the power requirements of the system. Customers are currently clamoring for an Apple Watch that goes longer between charges and is more independent of the iPhone. Accordingly, if the battery (and the rest of the assembly) were made thinner, to be more stylish and appeal to women with small wrists, the battery would have to grow in area to compensate.

That trade-off (thinner but more area) could well end up being a wash and while the Apple Watch would perhaps look cooler, it might not have dramatically more capacity.

And so, it's a very delicate balance between advances in the state of the art of the technology inside and the user expectations. Worse, while a thinner Apple Watch may look nice and fit some people better, it might be seen as a step backwards by those who really only care about not having to charge it every night.

Removing the battery during teardown. Image credlt: iFixit

For example, from iFixit's teardown, the current battery looks to be, very roughly, 5 mm thick. Reducing the overall thickness by 1 mm and making it no larger would cut its capacity by 20 percent. Not good.

It's impossible to surmise how the design of the Apple Watch will go in its next version and what advances Apple can make in the four areas above. But I think it's safe to say that if the Apple Watch 2 is any thinner, there won't be substantial improvement in the time between charges.

Apple's task will be a design trade-off combined with marketing campaign that makes the customers appreciate (and want) the next version of the Apple Watch even as they ignore the fact that dramatic gains are not in the offing so soon after version 1.0.

I wouldn't be surprised if, for now, Apple settles for a better battery, a larger battery, a less power-hungry SoC and leaves the squishy concept of "thinner" to the future. Apple has years, decades, ahead to achieve that.

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Lee Dronick

Perhaps slighly larger dimensions would allow for it to be thinner.


Don’t know the physics as to how much power it can generate given its size but a generator (dynamo since output is DC?) as in the Seiko Kinetic watches?

Lee Dronick

From Seiko’s website: “As in all existing Kinetic calibers, the wearer automatically generates electrical energy by her/his wrist movement. With Kinetic Direct Drive, however, the wearer can also generate energy by winding the crown.”


According to the literature for my Kinetic watch, when fully charged, it can sit on the shelf and keep running for 6 months.  I would think then that the dynamo generates enough juice to keep an iWatch running nonstop as long as you are wearing it on your wrist and aren’t comatose?

Lee Dronick

I wonder how big is the dynamo. Would including one take to much battery space?

Put batteries or a dynamo on a wrist band. It would act like an external battery so you can wear a regular band if you want.


1. Size, how about a bigger Apple Watch. Even the largest one is tiny on my wrist, when i try it on i thought it was designed specially for female. Surely most male watch would be slightly bigger?

2. SoC, the S1 is done on 28nm, but Ultra Low Power Variant, I am not sure if there are anything similar for 16nm yet. Assuming Apple has something similar working with TSMC, using state of the act component, this SoC, or SiP as Apple call it could reduce energy cost by 50%.

3. There is not much you can do with OLED. Even assuming you can squeeze another 10% out of it, there is little difference in the whole scernerio.

4. The most energy consumption is properly the wireless part. Which although helped by the newer SoC tech, still has it fundamentals limit.

5. So assuming Apple could get all of the above together, it could theoretically reduces energy usage by half.

Battery, there is actually quite lot to be done here. While what the article suggest is true, Lithium-Ion battery only ever increase so slightly, but there is nothing stopping Apple to use other Battery tech!.

One of the property of this battery we dont need is how long the energy would stay within. What if, there are battery that offer 2x the capacity but would naturally run its course every 5 - 7 days?


I like the idea of a bigger watch, but as you grow the watch, so goes the screen size, which sucks more battery juice. Of course, solar charging would be good, although I doubt it would be worth the real estate it would take to add sufficient charging capability. Kinetic concept is good as well. Personally, I think the answer is wireless charging. I spend probably 6-8 hours at my desk each day, with one hand on the mouse and the other either on the keyboard or at rest to the left side. A thin desktop pad that can wireless charge the watch if my wrist is within 4 inches or so of the desk would be awesome. Maybe work it into the metal bands somehow, so it is charging when the band is near the pad, maybe charge faster when the band is touching the pad. Of course, if Apple could roll charging techniques into the bands as well, that would be awesome, and maybe where they are going with the band-to-watch connections that are already there. Imagine solar bands. Or roll the kinetic potential into the bands. Or the wireless charging (or touch charging) from a desktop charging pad directly to the metal band that then charges the watch through the connector. Lots of potential there. Or, incorporate batteries into the bands to help supplement the watch battery.

My ideal Watch - 50 mm square, half the thickness, slightly curved OLED screen, metallic band with integrated batteries and wireless charging. Charging pad for my desk. Wear 23.5 hours a day, 7 days a week. Wake up (check sleep quality via Health), take watch off, direct charge for 30 minutes while I shower/shave/prep/dress, put watch on while I drive to work (wireless charging in the steering wheel???), work all day, spending a lot of time working at desk/computer (wireless charging while I work), workout after work, eat dinner, go to sleep (with watch still on - still charged from wireless charging at work), repeat daily. Now that would be very cool. Of course, adding a scanning mode to calculate the details of the meal in front of me (calories, protein, fat, carbs, sugar, salt, etc.) is hopefully in the works as well!! grin

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