Apple investigating replaceable Apple Watch battery packs

Adding extra hardware to an Apple Watch is difficult, due to the relative lack of attachment points available on the compact and sleek wearable device. Apple has come up with a way to use the band slots, used to affix watch straps to the Apple Watch, to hold a rear plate in place.

Granted today, Apple's patent for an "Auxiliary electronic device attachable to a wearable electronic device" shows how an add-on plate could be placed on the Apple Watch rear, while two sections on either end extend to fit into the band slots. In order to keep the Apple Watch wearable, the extended sections include their own slots for the band to fit inside.

This arrangement gives the effect of minimal changes to the appearance of the Apple Watch when viewed from the front, but while it will make the entire assembly thicker, the extra plate section will be partially hidden from view due to being placed between the Apple Watch and the user's wrist.

To help keep the back plate in place, the patent suggests the use of an alignment magnet to maintain its position, allowing for any connections it makes with the host Apple Watch to optimally function.

Apple suggests this style of add-on could help add more functions to the Apple Watch that aren't normally offered, with the example giving involving adding GPS functionality. The Apple Watch has included GPS-style capabilities since the release of the Series 2 device line, so GPS is unlikely to be used in this case, but it does illustrate how the wearable device can be expanded using non-standard sensors.

More interestingly, one embodiment described in the patent is to use this extra back plate as a way to extend the battery life of the Apple Watch. The plate contains wireless charging coils and a battery, allowing it to be recharged at the same time as the attached Apple Watch.

The same coils could then be used to provide power to the Apple Watch when it is running low, acting in a similar way to how a battery-equipped case could be used to recharge an iPhone while on the move.

Apple's patent was originally filed on February 26, 2015, and credits David Nazzaro, Tyler Bushnell, and Javier Mendez for its creation.

It is unknown if Apple will start using such technology at some point, as Apple's employees file a large number of patent applications each week, and not all of the ideas end up in commercial products.

Apple has previously come up with a number of ideas to elaborate on the Apple Watch concept, including modular smart bands that could house extra sensors and components, instead of keeping them within the Apple Watch's main body. Rumors of such upgrade options have been around for a while, including speculation in May last year that Apple could add glucose monitoring to the Apple Watch using a smart band or similar concept.

Apple has also looked at how the Apple Watch can be worn by the user, receiving a patent in October 2017 for self-adjusting bands. The patent describes how a band can be automatically tightened to better fit the user, with the onboard tensioner helping improve data collected by the various onboard sensors.

Other firms have explored the idea of expanding the utility of the Apple Watch, but so far no-one has come up with a finished product, though one company seemed to come close before Apple made changes to watchOS. San Antonio startup WiseWear accused Apple of foul play when it filed for bankruptcy in March, claiming the deactivation of the Apple Watch diagnostic port hidden in one Watch Band slot effectively devalued a patent it had acquired relating to a smart band accessory for the device.