51 days of battery life. The new most expensive Amazfit smartwatches yet have a solar panel on the front and back

Since August, we’ve been assembling these watches from fragments — from the Zepp app code, from certifications, and finally from leaked promo graphics where the back side of the case was missing. And yet, it was precisely that part that mattered. Today, it’s officially out, and it turns out that Amazfit meant the “Dual” label completely literally.

Sun from both sides. Watches like this have never existed before.

According to the manufacturer, the T-Rex Dual Solar are the first AMOLED watches with bidirectional solar charging. The front collects energy through the display surface — something the competition also does. The new thing is the second one: the back of the case is made of a glass-ceramic plate that acts as a second solar cell and has more than double the active area of the front panel.

The result is practical, and Amazfit admits it in its marketing just as openly: the watches collect the most energy when you’re not wearing them. During your break, you take them off and clip them to your backpack or tent so the back faces the sky. This exact scenario was what we estimated in the leaks article — and now it’s an official selling point.

The battery life figures are impressive. The small print too.

The foundation is a 660 mAh battery and 25 days of normal use without any sun. Three hours per day on the front panel extends it to 34 days, the same three hours on the back panel up to 51 days. With intensive use, it’s 13, 15 and 18 days. In power-saving watch mode, the watches last 60 days, and in an extreme outdoor mode 40 days.

But you need to slow down here. All solar figures are calculated with three hours per day at an intensity of 50,000 lux. That’s direct summer sun in an open area, not a November afternoon here. From the same “bucket” comes also the 180-day number that appeared in headlines — it applies to an extreme outdoor mode with continuous illumination, not everyday wearing. In real use, expect solar charging to extend battery life nicely, but save those best-looking numbers for a mountain vacation.

Titanium, sapphire and fifty meters under water

The case has a diameter of 51.4 mm and a thickness of 16.9 mm, even with the heart-rate sensor. The bezel and buttons are made of Grade 5 titanium, the frame is a fiber-reinforced polymer, and the display is covered by sapphire glass. There’s no lack of certification to military standards or a low-temperature mode designed to keep key functions running down to −30 °C.

Maps and route planning right on your wrist

The watches come with preinstalled colorful maps, and you can also add contour maps and ski maps. Plan your route directly on the watch, without a phone and without a signal—and you can save up to one hundred routes. Navigation works turn-by-turn, you can search nearby places, and the watch automatically recalculates when you leave the route. Map rendering should be 2.5× more power-efficient and map updates 12× faster than before.

For solo adventurers, the location sharing LiveShare is interesting—it shows your loved ones in real time where you are. There’s also a built-in flashlight with white and red light, plus a boosted mode and an emergency SOS signal. However, Amazfit itself notes that LiveShare doesn’t replace a rescue device—it requires a data-enabled phone and isn’t available everywhere.

You pay for solar with the display and the battery

And now what you can’t read from the press release. Despite the biggest case in the T-Rex lineup, the T-Rex Dual Solar has a smaller display than cheaper models—1.32 inches instead of 1.5 inches on the T-Rex Ultra 2 and the 48 mm version of the T-Rex 3 Pro. The battery is smaller too: 660 mAh vs 870 mAh on Ultra 2.

You can see it in the numbers without the sun. Ultra 2 lasts 30 days, Dual Solar 25. In GPS mode with high accuracy, it’s 50 hours vs 41. In other words: you’re not buying solar charging as an extra bonus, but as a trade-off for a smaller display area and battery capacity. That makes sense on multi-day hikes where the outlet is far away. In a typical city week, Ultra 2 is better on paper.

Price and availability

On the European e-shop, Amazfit T-Rex Dual Solar costs €649.90 and is available so far in just one color: Basalt Black. Shipments are expected to start in mid-October. For comparison, on the same e-shop today, T-Rex Ultra 2 costs €549.90 and T-Rex 3 Pro costs €399.90—so the new watches are the most expensive T-Rex models Amazfit has sold so far.

Inside the box, you'll find a silicone quick-release strap and a charging cradle compatible with USB-C. There’s no cable included, and the packaging is made from 100% recyclable materials. Whether the watch will also make it to Slovak retailers, and at what price, Amazfit has not announced yet.

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