'Reserve Strap' Debuts New Design Focusing on Apple Watch Diagnostic Port

Originally announced by third-party developers Lane Musgrave and John Arrow back in early March, one of the biggest concerns of the battery-boosting accessory "Reserve Strap" was its use of the Apple Watch's heart rate sensor as a way to provide power to the wearable. Although it was unconfirmed, there was always a possibility of the Reserve Strap obstructing normal functions of the heart rate sensor, or causing the Watch to not function altogether by interfering with skin contact completely.

Last week, after getting their hands on an Apple Watch, Musgrave and Arrow have gone back to the drawing board on the design of the Reserve Strap, coming up with a new look that acts as more of a traditional Apple-made band without blocking the heart rate sensor at all. The new Reserve Strap aims to use the 6-pin diagnostic port - hidden inside of the band port on the bottom of the Watch - as the main source of providing power to the device, shirking the heart rate sensor's magnetic inductive charging altogether.

reserve strap change

The Original Reserve Strap design (left) vs the new design (right)

Finally getting our hands on the Apple Watch has further confirmed the immense value of the Reserve Strap. Since release day, we've been executing series of tests on the Apple Watch and have some really exciting news to share today.

We've developed and tested a completely rethought design that takes advantage of the 6-pin port underneath the band slide of the Apple Watch. This port hadn't been deciphered by anyone until now but we've been able to make significant enough observations so far to warrant shifting our development focus to this new method. We're looking forward to sharing more design details and technical specification of this new Reserve Strap as soon as we can.

The company claims in its blog posts that its engineers have "been able to independently confirm that the 6-pin diagnostic port underneath the Apple Watch case can be used for charging." They continue by also noting the diagnostic port will allow for not only a higher charge capacity, but faster, more efficient charging times. The blog post also notes that the new method should improve durability of the strap as a whole and eliminate "any interference with Apple Watch functionality including taptic feedback and heartrate sensors."

reserve strap port sketch

Initial renderings of the new design (left) vs fully realized 3D model (right)

No word was given on the planned Kickstarter for the Reserve Strap, but those interested can still pre-order the device from the company's official website for $249.99. Color options will include white, gray and black, and customers will be able to choose between 38mm and 42mm strap sizes to fit their preferred Apple Watch size.

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

Popular Stories

iOS 26

Everything New in iOS 26.2 Beta 3

Monday November 17, 2025 3:20 pm PST by
Apple provided developers with the third beta of an upcoming iOS 26.2 update, and there are still new features that are being added with each beta that we get. We've rounded up all of the changes that Apple made in beta 3. AirDrop Apple added new AirDrop functionality, providing a way for two people to share files temporarily without having to add one another as contacts. iOS 26.2...
applecare apple care banner

Apple Brings New AppleCare+ Options to India

Tuesday November 18, 2025 8:42 am PST by
Apple today announced an expansion of AppleCare+ coverage in India, with new options for monthly and annual plans, and the addition of Theft and Loss for iPhone for the first time. Options for monthly and annual AppleCare+ plans in India provide more choice and flexibility, allowing users to keep coverage for as long as they require. Apple's vice president of Worldwide iPhone Product...
iPhone 17 Pro Cosmic Orange

10 Reasons to Wait for Next Year's iPhone 18 Pro

Wednesday November 19, 2025 4:00 am PST by
Apple's iPhone development roadmap runs several years into the future and the company is continually working with suppliers on several successive iPhone models at the same time, which is why we often get rumored features months ahead of launch. The iPhone 18 series is no different, and we already have a good idea of what to expect for the iPhone 18 Pro and iPhone 18 Pro Max. One thing worth...
Apple Wallet ID Illinois

iPhone Driver's License Feature Launching in Illinois

Tuesday November 18, 2025 8:47 am PST by
In select U.S. states, residents can add their driver's license or state ID to the Wallet app on the iPhone and Apple Watch, providing a convenient and contactless way to display proof of identity or age at select airports and businesses, and in select apps. Starting this Wednesday, November 19, the feature will be available to residents of Illinois. The announcement confirmed that the...
iPhone 17 Pro and Air N1 Feature

iPhone 17 vs. iPhone 16 Wi-Fi Speeds: New Study Reveals the Winner

Tuesday November 18, 2025 10:53 am PST by
A new study has revealed that the iPhone 17, iPhone 17 Pro, iPhone 17 Pro Max, and iPhone Air achieve significantly faster average Wi-Fi speeds compared to the iPhone 16 series, thanks to Apple's custom-designed N1 chip. The study was conducted by Ookla, the company behind the popular Speedtest website and app. It said the results are based on global, crowdsourced Speedtest user data...
macbook black friday

The Best Early Black Friday Mac Deals

Tuesday November 18, 2025 7:32 am PST by
We're getting closer to Black Friday, which lands next week on Friday, November 28. In the lead-up to the shopping holiday, we're tracking a few lowest-ever prices on Apple's most popular Macs, including the M4 MacBook Air and brand new M5 MacBook Pro. Note: MacRumors is an affiliate partner with some of these vendors. When you click a link and make a purchase, we may receive a small payment,...
Magic Keyboard Touch ID Feature

Apple Releases New Firmware for 140W USB-C Power Adapter, Magic Keyboard and Magic Trackpad

Tuesday November 18, 2025 1:05 pm PST by
Apple today released updated firmware for several accessories, including the 140W USB-C Power Adapter, the Magic Trackpad 2, the Magic Trackpad USB-C, the Magic Keyboard with Touch ID, and the Magic Keyboard with Touch ID and Numeric Keypad. There is no word on what's included in the updated firmware at this time, but it could offer performance improvements and security updates. Accessory...
Apple Sports App Preview Feature

Apple Sports App on iPhone Now Available in More European Countries

Monday November 17, 2025 6:27 am PST by
The free Apple Sports app on the iPhone was released in additional European countries today, including Belgium, Croatia, Czechia, the Netherlands, Luxembourg, Poland, Hungary, Denmark, Finland, Norway, Sweden, Switzerland, Slovakia, Slovenia, Serbia, Greece, Estonia, Latvia, Romania, Ukraine, and others. The app was already available in the U.S., the U.K., Canada, Austria, France, Germany,...
best early black friday deals

Best Black Friday Apple Deals Live Now - Save on AirPods, iPads, and Apple Watches

Saturday November 15, 2025 1:45 pm PST by
We're officially in the month of Black Friday, which will take place on Friday, November 28 in 2025. As always, this will be the best time of the year to shop for great deals, including popular Apple products like AirPods, iPad, Apple Watch, and more. In this article, the majority of the discounts will be found on Amazon. Note: MacRumors is an affiliate partner with some of these vendors. When ...
ipad mini 7 feature red and blue

iPad Mini 8: Four Major New Features to Expect

Wednesday November 19, 2025 7:50 am PST by
Apple's eighth-generation iPad mini is highly likely to arrive next year, offering a significant refresh of the device with at least four major new features. OLED Display The next-generation version of the iPad mini could feature an OLED display, as part of Apple's plan to expand the display technology across many more of its devices. Apple's first OLED device was the Apple Watch in 2015, ...

Top Rated Comments

DannyT2011 Avatar
138 months ago
It won't work. Look at the connector. Those of us who have our watches already know that the way to attach a strap is to slide it in. Straps won't slide with a big connector sticking out of them.

It looks like there are buttons on either side of the strap that you would pinch to insert/release. Perhaps as you pinch them, the connector will retract and then will connect to the port when you release them?
Score: 13 Votes (Like | Disagree)
elmateo487 Avatar
138 months ago
It won't work. Look at the connector. Those of us who have our watches already know that the way to attach a strap is to slide it in. Straps won't slide with a big connector sticking out of them.

Lol. This made me laugh. They have engineers who can extract info from a diagnostic post... Yet you think they didn't think of that? Especially since they have one in their hands now.
Score: 6 Votes (Like | Disagree)
Jandmtv Avatar
138 months ago
Apple covered that port for a reason. Good luck with that strap in the rain.

Yup, only to include it as a new feature with the watch2.
Score: 6 Votes (Like | Disagree)
shareef777 Avatar
138 months ago
Apple covered that port for a reason. Good luck with that strap in the rain.
Score: 6 Votes (Like | Disagree)
dannys1 Avatar
138 months ago
I take it these people are aware that having batteries in a watch band is something Apple has patented.

Which begs the question, why didn't they launch with battery bands?
Score: 6 Votes (Like | Disagree)
shareef777 Avatar
138 months ago
We all know the watch needs the iPhone to operate, and the iPhone doesn't last more then 18 hours so why does the watch need to? If you have to recharge your iPhone every night, it should be easy enough to charge the watch as well.
Score: 5 Votes (Like | Disagree)