'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 (Neutral)

Popular Stories

imac video apple feature

Apple Unveils First New Products of 2026

Monday January 26, 2026 1:55 pm PST by
Apple today introduced its first two physical products of 2026: a second-generation AirTag and the Black Unity Connection Braided Solo Loop for the Apple Watch. Read our coverage of each announcement to learn more:Apple Unveils New AirTag With Longer Range, Louder Speaker, and More Apple Introduces New Black Unity Apple Watch BandBoth the new AirTag and the Black Unity Connection Braided...
Apple Logo Black

Apple Just Made Its Second-Biggest Acquisition Ever After Beats

Thursday January 29, 2026 10:07 am PST by
Apple today confirmed to Reuters that it has acquired Q.ai, an Israeli startup that is working on artificial intelligence technology for audio. Apple paid close to $2 billion for Q.ai, according to sources cited by the Financial Times. That would make this Apple's second-biggest acquisition ever, after it paid $3 billion for the popular headphone and audio brand Beats in 2014. Q.ai has...
iPhone 5s

iPhone 5s Gets New Software Update 13 Years After Launch

Monday January 26, 2026 3:56 pm PST by
Alongside iOS 26.2.1, Apple today released an updated version of iOS 12 for devices that are still running that operating system update, eight years after the software was first released. iOS 12.5.8 is available for the iPhone 5s and the iPhone 6, meaning Apple is continuing to support these devices for 13 and 12 years after launch, respectively. The iPhone 5s came out in September 2013,...
Apple Creator Studio

Apple's Next Launch is Today

Tuesday January 27, 2026 2:39 pm PST by
Update: Apple Creator Studio is now available. Apple Creator Studio launches this Wednesday, January 28. The all-in-one subscription provides access to the Final Cut Pro, Logic Pro, Pixelmator Pro, Motion, Compressor, and MainStage apps, with U.S. pricing set at $12.99 per month or $129 per year. A subscription to Apple Creator Studio also unlocks "intelligent features" and "premium...
apple silicon 1 feature

Apple Responds to Skyrocketing RAM and Storage Chip Prices

Thursday January 29, 2026 2:40 pm PST by
On an earnings call with equity analysts today, Apple CEO Tim Cook responded to fast-rising RAM and SSD storage chip prices in the supply chain. Prices for RAM and NAND storage chips are surging lately due to high demand from companies building out AI servers, resulting in supply constraints. Cook said that rising memory chip prices had a "minimal impact" on Apple's gross margin in the...

Top Rated Comments

DannyT2011 Avatar
140 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
140 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
140 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
140 months ago
Apple covered that port for a reason. Good luck with that strap in the rain.
Score: 6 Votes (Like | Disagree)
dannys1 Avatar
140 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
140 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)