Teardown: Smartwatch embeds dual power sources

Article By : Brian Dipert

As the wearable electronics market evolves and matures, smartwatches are taking different paths to differentiation.

As the wearable electronics market evolves and matures, different smartwatch vendors (and different products within each vendor’s line) are taking different paths to differentiation and (hopeful) success. Most devices are all-LCD or -OLED across the entirety of the watch face. LG’s new Watch W7 takes the “unique” (and largely so-far panned, although as I write this I haven’t yet seen any hands-on reviews) approach of placing mechanical watch hands in front of the full-face digital display. Then there’s Martian’s G1 and successor products, which devote only a portion of the face to a mini-OLED display for text-only notifications. They also offer Amazon Alexa, “OK Google,” and Apple Siri voice interface options via an integrated microphone and speaker along with a Bluetooth tether to a companion smartphone, a capability which was the primary motivation for this teardown.

Martian may not be a familiar name to you; it wasn’t to me until I saw its watches show up on closeout site Meh several times. Once the price dropped to $29 (plus $5 for shipping) I could no longer resist my curiosity and entered my credit card. Like Pebble, Martian started out as a Kickstarter-funded project back in 2012; the initial G1 family was succeeded by the mVoice (showcased here) and simpler mVip product lines. Martian returned to Kickstarter for the G2 family in late 2017, but the company’s reportedly now down for the count; its website is still up and running, but everything’s listed as being “out of stock,” and retailers like Amazon and Meh seem to just be working through remaining warehouse inventory.

Enough of the background, on to the teardown. I’ll start out with a few obligatory unboxing shots:

The mVoice product line was a fairly diverse combination of various colors and styles of faces, hands, and bands (which I suspect may have been part of the company’s challenge … too much proliferation can lead to line item management nightmares versus being willing to “not optimally serve everyone” in exchange for a more focused product portfolio … not to mention the lukewarm-at-best reviews):

I think mine was pretty nice looking; it was a bit difficult to begin to dissect as a result, knowing I’d likely never get it back together again intact and fully functional:

Slipped behind the watch were two scant pieces of documentation:

And tucked into the watch band was a micro-USB-to-USB cable (employed by the mVoice for charging purposes), which I’ll be able to use in the future:

The left side of the watch encompasses the charging port (above) and speaker (below):

while on the right are three control buttons and (below them) the microphone:

Now for the back panel:

The other thing I’ll potentially be able to use in the future is the (nice, IMHO) leather band; it’s 22mm in width, easily removed and replaced, and uses an industry-standard clasp:

After removing four screws, thanks to my iFixit 64-bit driver kit, it’s time to dive inside:

The item glued to the back panel and cable-connected to the PCB is, perhaps obviously, a lithium polymer battery. But what’s that within the circular cutout in the PCB … is that another coin battery cell (stay tuned)? The other obvious item discernible in this overview shot (aside from multiple ribbon cables and multi-wire harnesses) is the speaker in the lower right corner of the PCB.

Here are closeups of both the lithium polymer battery and its connector at the PCB:

Not desirous of an explosion I didn’t try to peel the battery away from the panel 😉

Looking closely at the PCB, two screws were in obvious view, which I removed:

Peeling off the polka-dot stickers on the PCB revealed three more screw heads underneath:

In doing so, I realized that the “ring” around the watch frame was made of soft rubberized material (likely intended as an environmental seal), no hard plastic, and was easily removable:

I was able to get two of the three off, but the head on the third one stripped (and the rubber band trick didn’t help). It ended up only being used to attach one of the side-button “spring” contacts to the PCB so its removal was unnecessary for overall disassembly:

Disconnecting the ribbon cable between the main PCB and the micro-USB module, enabled removal off the latter:

Here are some micro-USB module closeups:

After removal of the rubber gasket, I started carefully wrestling the PCB assembly out of the watch frame, assisted by a flat head screwdriver-as-lever and beginning with the lower edge. Here’s what the end of the speaker module looks like:

And the microphone has now popped into view, too:

With the PCB assembly free of its confines, here’s what its backside looks like:

Here’s a closeup of the now-visible OLED module:

And here’s what’s left inside the watch; that IS a coin cell!

Here’s a closeup:

What Martian seemingly did here, which was surprising at first but seems quite clever in retrospect, was to leverage a mainstream, mature, cost-effective mechanical clock module (including its own battery) for the clock hands, relying on the lithium polymer battery to power the remainder of the watch. Coin cell replacement could occur fairly easily via the cutout in the PCB, once the back panel was removed.

[Continue reading on EDN US: PCB components]

—Brian Dipert is Editor-in-Chief of the Embedded Vision Alliance, and a Senior Analyst at BDTI and Editor-in-Chief of InsideDSP, the company’s online newsletter.

Subscribe to Newsletter