Amazfit T-Rex Dual Solar brings first solar AMOLED, charges front and back
Zepp Health has finally made the T-Rex Dual Solar official, and the name really does describe what is going on here. There is a solar panel at the front, another much larger one on the back, and the company reckons the unusual setup can stretch battery life quite a bit.
The back of the watch is basically a second solar charger
Most solar watches have a pretty obvious limitation. The useful surface area faces upwards, so manufacturers have to squeeze their solar collection system around or underneath the display without ruining screen quality.
Zepp Health has gone in another direction. The T-Rex Dual Solar collects energy through the AMOLED display, but it also has a second solar panel built into its glass-ceramic caseback. That rear surface has roughly twice the collection area of the front panel.
Obviously, sunlight is not getting to the back while the watch is sitting on your wrist. So the idea is that you take it off when you stop, turn the caseback towards the sun and let the larger panel do its thing. Zepp Health even suggests attaching the watch to a backpack or tent during longer stops.
So there are two firsts here. As far as we can verify, no major sports-watch brand has previously sold a genuinely solar-charging AMOLED watch. Plus you get the dual charging feature.
The battery numbers get pretty wild
Without any help from the sun, Amazfit rates the T-Rex Dual Solar for up to 25 days of typical use. Give the front panel three hours per day at 50,000 lux and that climbs to 34 days.
Do the same with the larger rear panel and the claimed figure reaches 51 days. The watch carries a 660mAh battery, while Accuracy GPS Mode is rated for up to 41 hours.
There is an even bigger number buried in the figures for Outdoor Extreme Mode. That setting strips things back to the essential outdoor functions and can deliver up to 40 days without solar. With continuous rear-side solar replenishment at 50,000 lux, Amazfit quotes up to 180 days.
That 180-day number needs some context. It is not six months of normal smartwatch use, and it assumes sustained light exposure while using a heavily reduced power mode. Still, it shows why Zepp Health bothered putting such a large photovoltaic surface on the back rather than relying entirely on the display.
There is another potentially useful aspect to the system. Zepp Health says solar energy can bring a completely depleted watch back to life when conventional charging is unavailable, restoring access to things such as maps and route information. For multi-day trips, that can be a life saver.
This is a big T-Rex
The Dual Solar isn’t exactly subtle. The case measures 51.4mm across and 16.9mm thick including the heart-rate sensor, while the watch itself weighs 69 grams before you add the strap. Inside that large case sits a relatively compact 1.32-inch AMOLED display with a 466 x 466 resolution and up to 3,000 nits of peak brightness.
Zepp Health has gone fairly premium with the materials. The bezel and four buttons use Grade 5 titanium, while sapphire glass protects the display. The watch also carries a 10 ATM water-resistance rating and supports recreational diving to 50 metres.
There is a proper LED flashlight as well. It packs a 200-lux white beam under normal operation, with a 300-lux Boost mode and SOS functionality. Anyone who has used the flashlight on the Amazfit T-Rex 3 Pro will already know how handy having a dedicated light on an outdoor watch can be.
Maps and navigation are a big part of the package
The solar system will obviously grab most of the attention. But Zepp Health is clearly pitching this as an expedition watch rather than simply a T-Rex with an unusual battery trick.
There are full-colour preloaded maps with expanded road coverage, downloadable contour and ski maps, turn-by-turn navigation, waypoint navigation and POIs. A new Navigation Gradient Curve shows upcoming climbs and descents using a colour-coded elevation profile, while LiveShare can send your real-time location, heading and activity information to friends or family.
Positioning uses dual-band GNSS with six satellite systems and a circularly polarised GPS antenna. The sensor package includes Zepp Health’s BioTracker 6.0 PPG sensor, barometric altimeter, compass, temperature sensor, gyroscope and accelerometer.
The price is perhaps the other big story here. The T-Rex Dual Solar is on sale for $649.99. The company has spent years undercutting the established premium sports-watch brands, but this price-tag puts the Dual Solar in Garmin territory. That said, the hardware also looks considerably more ambitious. Two solar surfaces, sapphire glass, Grade 5 titanium, proper mapping and the ability to deliberately charge the watch from its caseback make this a pretty feature-packed device.
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