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Apple Watch Series 4 Teardown: 20% Less Battery Capacity, Hidden Barometric Sensor, and Streamlined Internals [Updated]

iFixit has completed a teardown of the Apple Watch Series 4, providing a look inside a larger 44mm model with LTE.

Image Credit: iFixit

The repair experts believe that while the original Apple Watch was awkwardly layered together and used too much glue, the Series 4 lineup feels "much more thoughtfully laid out," likening it to the iPhone 5.
Apple pundit John Gruber has compared this to the leap in design brought by the iPhone 4, and we might even go a bit further and call it an iPhone 5: a device that knows its priorities, and wants to look as elegant inside as out.
At first glance, the internal design of Series 4 models looks more or less the same as previous models, with the battery and Taptic Engine taking up most of the space. Dig deeper, however, and the changes become evident.

Image Credit: iFixit

Teardown highlights:
  • 1.12Wh battery in the 44mm model, which is 20% less capacity than the 1.34Wh battery in 42mm-sized Apple Watch Series 3 models.
  • A thinner and longer Taptic Engine, but iFixit says it still takes up a lot of space that could have gone to a larger battery.
  • The barometric sensor may have been relocated to the speaker grille for access to the outside atmosphere. The sensor had its own dedicated hole beside the microphone on Apple Watch Series 3 models.
  • The new Apple S4 chip is secured only with screws, whereas the processor is also "fiercely glued" in previous Apple Watch models.
  • The golden ring is likely a streamlined antenna system, as iFixit says it has not seen the usual fiddly brackets or golden gaskets.
  • The entire rear casing pops off more easily.
  • The display is not only larger, but also thinner.
iFixit says the Apple Watch Series 4 is nearing iPhone levels of repairability, with the highly-glued display being the primary remaining obstacle. Beyond that, they say the battery is straightforward to replace.

Image Credit: iFixit

All in all, the Series 4 received a "solid" 6/10 on iFixit's repairability scale, with 10 being the best possible score. That's the same repairability score iFixit gave the iPhone XS and XS Max in its teardown of those devices.

Update: A previous version of this article said Apple Watch Series 4 models have 4% more battery capacity, as iFixit mentioned, but that was based on comparing a 44mm Series 4 model with a 38mm Series 3 model. 44mm and 40mm Series 4 models actually have 20% less battery capacity compared to 42mm and 38mm Series 3 models respectively, although Apple says battery life remains up to 18 hours.

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Top Rated Comments

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11 weeks ago
It’s always awesome to be reminded of the fact that these are tiny computers strapped to your wrist. Each one is probably more powerful than the computers used to render dinosaurs in Jurassic Park.

Rating: 14 Votes
11 weeks ago
What a beautiful piece of engineering!
Rating: 13 Votes
11 weeks ago
Amazing tech. How far we've come from my Spectrum and Amiga days!
Rating: 9 Votes
11 weeks ago

Just remove the Taptic engine and you got more batetery :confused:


but we need the taptic engine to get notifications without sound.
Rating: 7 Votes
11 weeks ago

If the watch is waterproof and dustproof how does air pressure get to the barometer?

The barometer senses pressure, not dust and water. iFixit says they put it behind the speaker, open to the air.
The sensor is waterproof and dustproof. It means it is not damaged by water and dust. It doesn't mean it doesn't get wet or dusty.
Rating: 4 Votes
11 weeks ago

Of course there is waterproof. Anything made out of materials that contact with water doesn't affect is waterproof. The spoon I am currently holding is waterproof. Anything completely encased in material that isn't affected by water is waterproof. Encase something in (originally molten) glas and it is waterproof. With the right glue, you can waterproof a lot of things.

One can distinguish between seals that can be opened and closed and something that is sealed by filling a gap with a material that is liquid originally and thus can enter all nooks and crannies. In particular with water, due to its surface tension, if a capillary connecting the inside with the outside becomes small enough, it is hermetically sealed (of the course the surface tension translates into capillary pressure which then has to be compared to the ambient pressure, but if we limit ourselves with ambient pressures a human can survive in that is a very attainable limit).


Obviously we are talking about devices here and not spoons, rocks and stuff stuff like that. But if we are going to be absurd that spoon you mention isn't water proof (eventually stainless will corrode, it is just resistant) and the glass encased thing you made up would shatter at depth if there were any voids whatsoever.

Currently there is no industry standard in order for a device to classify as waterproof and thus "waterproof" can not be claimed as a product feature. Even things like dive watches/computers/etc are merely water resistant.
Rating: 4 Votes
11 weeks ago
Incredible internals. Quite an age we are living in!
Rating: 3 Votes
11 weeks ago
Yeah, she is a beauty for sure.
Rating: 3 Votes
11 weeks ago
same battery in either 40 or 44mm size?
Rating: 3 Votes
11 weeks ago

Amazing tech. How far we've come from my Spectrum and Amiga days!


We slowly got accustomed to technology but this would be considered alien tech or downright magic by last century people.
Rating: 2 Votes

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