40mm Apple Watch Series 5 Features New Battery Design, 10% More Capacity

A teardown of the 44mm Apple Watch Series 5 conducted by repair site iFixit found few design changes compared to the 44mm Apple Watch Series 4, but a subsequent teardown of the 40mm model has found some more significant design deviations.

The battery inside of the Apple Watch Series 5 has a new metal casing, likely constructed from aluminum, rather than the foil pouch that surrounds most lithium-ion batteries.

newapplewatchbatterydesign
Based on an Apple patent, iFixit suggests that the new metal casing is designed to be a more space-efficient method for sealing batteries. The size of the battery compartment in the Series 5 doesn't appear to have changed significantly over the Series 4 model, but the battery in the Series 5 offers 10 percent larger capacity than the Series 4 (0.944Wh vs. 0.858Wh).

Foil pouches feature a larger seal than the metal enclosure, so with the design change, Apple may have been able to use the space saved for a slightly larger battery.

newvsoldbatterydesignapplewatch

New battery design on left, old design on right

iFixit says that the metal casing also makes the battery physically stronger, which is ideal for repair purposes. An aluminum enclosure makes it more difficult to puncture during repairs.

The new design is limited to the 40mm Apple Watch Series 5 and was not seen in the 44mm Series 5 model. iFixit says that it's not clear why the updated design was used in one watch and not the other, but it could be that the smaller watch needed additional battery or Apple wanted a "low-key" way to test the design.

Related Roundup: Apple Watch 11
Buyer's Guide: Apple Watch (Buy Now)

Popular Stories

Home Hub Command Center with Dome Base Feature

Apple Working on All-New Operating System

Thursday September 25, 2025 1:11 pm PDT by
Apple is developing an all-new operating system codenamed "Charismatic," according to Bloomberg's Mark Gurman. Apple smart home hub concept based on rumors This is likely Apple's long-rumored "homeOS" operating system. In a report last month, Gurman said both Apple's rumored smart home hub in 2026 and tabletop robot in 2027 will run the new operating system. He said the software platform ...
iOS 26 Battery Glass Feature

iPhone 16 Pro Max 80% Charge Limit: One Year Later, Was It Worth It?

Wednesday September 24, 2025 3:58 pm PDT by
With the iPhone 15 series, I did an experiment and kept my iPhone's Charge Limit set at 80 percent for an entire year. It provided an interesting look at the impact of charge limits on battery longevity, so I decided to repeat it for the iPhone 16 line. Since September 2024, my iPhone 16 Pro Max has been limited to an 80 percent charge, with no cheating. As of today, my battery's maximum...
AirPods Pro 3 Newsroom

Apple's 'Back to School' Offer Ends Soon, Now Applies to AirPods Pro 3

Wednesday September 24, 2025 7:20 am PDT by
Apple's annual "Back to School" promotion for students ends soon, so act fast if you want to score free AirPods with the purchase of an eligible new Mac or iPad. Until Tuesday, September 30, college students and qualifying educational staff in the U.S. can receive free AirPods 4 with Active Noise Cancellation when they purchase an eligible new Mac or iPad from Apple. This is a $179 value. ...
iPhone 17 Pro Colors

Skipped the iPhone 17 Pro? Here's What is Rumored for iPhone 18 Pro

Tuesday September 23, 2025 8:55 am PDT by
While the iPhone 18 Pro and iPhone 18 Pro Max are still a year away, there are already a few rumors about the devices that offer an early look ahead. Below, we have recapped some of the early iPhone 18 Pro rumors so far. This story was published previously, and it has been updated to reflect the latest rumors. Many early rumors prove to be true, but nothing is confirmed yet, and Apple's...
iOS 26

Apple Continues to Prepare iOS 26.0.1 With Multiple Bug Fixes Expected

Sunday September 28, 2025 1:30 pm PDT by
Apple is preparing to release iOS 26.0.1, according to a private account on X with a proven track record of sharing information about future iOS versions. The account initially said iOS 26.0.1 would have a build number of 23A350, but they now expect the update to have a build number of 23A355. This suggests that the software update will include more bug fixes or changes than initially...
Apple More Personal Siri Ad

Apple Responds to U.S. Class Action Lawsuit Over Delayed Siri Features

Friday September 26, 2025 6:57 am PDT by
In March, Apple delayed the launch of its personalized Siri features, and soon after the company was hit with multiple class action lawsuits over the situation. The plaintiffs said they never would have purchased an iPhone 16, or would have paid less, had they known Apple's marketing about the Siri features was false. In the U.S., all of the complaints were consolidated into one class...
Apple MacBook Pro M4 hero

New MacBook Pro Nears Mass Production, But Four Bigger Upgrades Expected Next Year

Sunday September 28, 2025 2:08 pm PDT by
Apple's next MacBook Pro models will enter mass production soon, according to the latest information shared by Bloomberg's Mark Gurman. In his Power On newsletter today, Gurman said he continues to believe the new MacBook Pro models will be released at some point between late 2025 and the first quarter of 2026, meaning they should be available to order by March at the latest. Apple often...
iphone 17 ceramic shield

Regular iPhone 17's USB-C Charging Speeds Tested With Apple Chargers

Friday September 26, 2025 9:01 am PDT by
The website ChargerLAB has tested the standard iPhone 17 model's USB-C charging speeds with a variety of Apple's chargers, from 18W to 140W. The device reached a peak charging speed of around 27W to 28W with these Apple chargers:29W USB-C Power Adapter 30W USB-C Power Adapter 35W Dual USB-C Port Power Adapter 35W Dual USB-C Port Compact Power Adapter 40W Dynamic Power Adapter with 60W Max...
maxresdefault

Review: A Week With the iPhone 17 Pro

Friday September 26, 2025 12:51 pm PDT by
Apple's iPhone 17 models have been out for a week now, so we thought we'd do a longer-term review of the flagship iPhone 17 Pro and Pro Max now that we've been able to spend more time with them. Subscribe to the MacRumors YouTube channel for more videos. MacRumors videographer Dan Barbera has a Silver iPhone 17 Pro and a Cosmic Orange iPhone 17 Pro Max, and despite a lot of concern over...

Top Rated Comments

benshive Avatar
79 months ago

Personally don’t like the always on display. I would’ve upgraded if it had the normal display but bigger battery. I could get a couple of days out of a charge.
You can turn off the always on display.
Score: 15 Votes (Like | Disagree)
IRockThat828pScreen Avatar
79 months ago

Dissecting the baby right after its born
^this dude has had an account longer than I've been alive
Score: 8 Votes (Like | Disagree)
Rorosbutt Avatar
79 months ago
Personally don’t like the always on display. I would’ve upgraded if it had the normal display but bigger battery. I could get a couple of days out of a charge.
Score: 5 Votes (Like | Disagree)
44267547 Avatar
79 months ago

Maybe this new design will help pave the way for a larger battery in series 6 models next year?
It’s not the battery needs to become ‘larger’, it’s the efficiency of the chip and eventually Apple adopting micro LED, which will also help improve the battery life significantly.
Score: 5 Votes (Like | Disagree)
CarpalMac Avatar
79 months ago
This would never have been allowed if Jonny was still [S]alive[/S] popping into the office.

The watch would have been made thinner. Though, it is actually the one device Apple sells that could do with that!
Score: 4 Votes (Like | Disagree)
fmcshan Avatar
79 months ago
Maybe this new design will help pave the way for a longer lasting battery in series 6 models next year?
Score: 3 Votes (Like | Disagree)