Apple Watch 7: What new battery tech could mean for Garmin, Apple & Samsung

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Apple Watch 7 – New Battery tech & new design could boost life by 25%

Must Read: Apple Watch 7 Predictions

There’s a lot of chit chat amongst industry commentators about next week’s new Apple Watch 7 screen being a little bit larger, even more chat about the redesigned case format and further speculation that the old straps might fit the new Watch 7.

Unless there is some new screen tech then a bigger game-changer could be with the battery. Here’s why.

New Battery Tech hits the market.

The new WHOOP 4.0 band hit the headlines today and ships this month. The general chit-chat about WHOOP today was its new HR sensor. The chit-chat tomorrow will be founding members complaining that they will have to start paying a subscription in September 2023.

A much more impactful conversation would be about the battery tech that WHOOP 4.0 uses.

For the first time ever, a wearable’s Li-ion battery uses a silicon-based anode rather than a carbon-based one. The bottom-line for this tech is that the same capacity can be maintained by a 17% smaller battery ie about 20% more capacity for the same space if you do the math.

The battery maker is Sila Nanotech who received significant VC funding earlier this year to expand R&D. Ultimately Sila is gunning for the electric vehicle market but it seems to have taken a lucrative side road into wearables. I would imagine that the Sila Nanotech sales rep contacted all the big wearables companies and asked to pitch. I’m guessing that s/he had heard of Apple and made the call to them too!

It’s inconceivable that Apple & Garmin’s R&D doesn’t know about this. Whether or not they’ve bought it for the Apple Watch 7 or the next Garmin Venu 2 is, of course, speculation.

The like-for-like 18-hour battery life of the Apple Watch 6 would be boosted to 21-23 hours and the Garmin Venu 2 would see GPS+battery life raise from 22 hours to c25-27 hours should either of them use this tech.

Hold that thought.

A Bigger Apple Watch 7 screen also means a bigger case


Apple Watch 7 will be larger, now coming in a 45mm version rather than the existing 44mm.

There’s also going to be more space for a larger battery or some other component in the Apple Watch 7.

To estimate how much larger the battery could be, we need to know the internal volume and the current battery size. We can base estimates on these sizes


Image:, the depth of the AW6 is .41″/10.4mm

I guestimate the existing internal size of the 44mm AW6 is 38x32x6=7296mm3.

Increasing the length and width for the AW7 by1mm gives 39x33x6=7722mm3. That’s 426mm3 more or a 5.8% bigger volume

Let’s look at this teardown of the AW6 and see the battery in the bottom left of the image.


Image Credit: via

Conservatively, I’d say the battery takes up 1\8th of the volume. ie 7296/8=912mm3

If we assume that ALL the new space is used by the battery then the battery can now be increased by 426mm3, the number we found earlier ie 912+426=1338mm3 or 46% more!

This translates to another 8 hours more battery life – from 18 to 26 hours. Add in the silicon anode and we get 31 hours.

There’s also talk of other internal space savings being made with a double-sided CPU plus the CPU and other components could become slightly more energy efficient which itself extends the battery life.


Apple Watch 7 Battery Life?

Whilst the headline spec of the Apple Watch’s battery life has stayed at 18 hours for several years, the reality is that judicious use of GPS, SpO2 and HR can easily give a day and a half battery life.

Put that all together and the bottom line is that realistic battery life for the Apple Watch 7/8 could exceed two days/2 sleep cycles and a realistic best-case scenario could hit 3 days with a few features disabled.


What works against that?

OK, there’s a lot of assumptions there on every level.

I would further assume that any case changes made this year will be here to stay for several more years to come and yet I haven’t even considered the use of alternative screen tech and sensors that use less energy.

I would point out that Apple probably plans to incorporate the Rockley Photonics sensor in AW8/AW9 to measure lactate, blood glucose, hydration and other vitals via laser-based, IR spectrophotometry. That sensor is a working prototype but it looks quite big.



Maybe some of the extra space is intended for that component? Then again, the laser should be more energy-efficient than LEDs…

What does this mean for Garmin?

Whilst extra battery capacity would be welcomed by any wearable company, the impact on Garmin watches will be much less than the pure smartwatches made by Apple, Samsung, Fitbit/Google and others.

Garmin Venu 2 already has a multi-day battery life based on realistic/normal usage. Even adding an extra day won’t change Garmin’s marketing or your usage patterns too much. It wouldn’t be the same kind of game-changer that it could be for Apple.


Should we be excited for Apple Watch 7

Hmm. Probably not!

I originally expected a slight increase in battery capacity and a slight increase in component efficiencies to deliver a slight increase to the overall battery life.

The most realistic expectation about how Apple can deliver a (small) step-change increase in battery life lies in the availability of more internal space rather than the unrealistic use of cutting-edge tech. Apple tends to use well-proven tech.

Must Read: Detailed Apple Watch 7 Predictions


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9 thoughts on “Apple Watch 7: What new battery tech could mean for Garmin, Apple & Samsung

  1. I noticed the battery mention yesterday, interesting but hardly game changing. Even if Apple were to pull 20% increase in battery life, it will either be gobbled up by a larger screen, more onboard memory, and faster CPU, or it will just turn an 18-hour smartwatch into 22-hour one. Still days and weeks off the likes of Fenix, Enduro, and Vertix 2. Yes, it’s a smartwatch and no, it still demands daily charging if you do anything but walk around with it.

    But battery-shmattery!

    You are right! As a founding member, I am fully psyched and ready to complain about being forced into a subscription. In theory, they gave us a year free, but in practice I’m seeing shipment estimates reported in the vicinity of 9-10 weeks from now. Nobody’s getting this new and improved WHOOP before November, and suddenly a year free becomes 10 months, and then the whole new year is charged automatically. I think this undies, bra, and leggings making company that also does recovery could have at least had decency to count the year free from the date a member gets their new WHOOP.

    1. fenix etc are not valid comparisons
      aw6 screen i think is quite old tech. so a new tech, larger screen will probably use LESS juice.
      CPU is new each year. they’re doing a double-sided one. i guess if they get the nm’s lower it will use less juice. redesign could be mostly a space saving thing. IDK
      it’s 2 years on the whoop not one tho right? ie 2023. least that’s what i’m offered. i am checking on the 9-10 weeks thing….eesh

      1. Of course, you are right. Two years. It’s still 2021. Boy, I had two coffees today already, and it didn’t help…

    2. “The like-for-like 18-hour battery life of the Apple Watch 6 would be boosted to 21-23 hours and the Garmin Venu 2 would see GPS+battery life raise from 22 hours to c25-27 hours should either of them use this tech.”

      Apple fan boy trying hard to make it seem like the Apple Watch has battery life on par with Garmin devices…

      1. Apple fanboy! Finally I have that accolade alongside “Garmin fanboy” from someone else last month.

        You could be right but you could read these and they are based on devices that I buy myself …no PR freebies from Garmin…or from apple for that matter.
        I love great tech and don’t really care who makes it.:

        PS All wordpress sites can see your IP address when commenting!

  2. “Battery life for the Apple Watch 7 could exceed two days.”

    Here I am looking at my Garmin Fenix 6X Pro Solar that I charge maybe once every 2 weeks

    1. Which do you think will sell more, the Fenix 7 series or the Apple Watch 7 series?

      they’re different devices for different purposes and I always use one of my Garmins for every run/bike/swim.

  3. How can 25% boost of apple watch become a game changer if garmin can work for more than 1 week without charging 😀 desperate

    1. it’s a game changer for apple and their smartwatches and for the kind of watch with a hi res screen and other energy-consuming features.
      it’s not a game changer for garmin’s sports watches.

      the majority of manufacturer-specific content here is from Garmin…it’s nice to write about something different for a change.

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