That doesn’t bother me too much except for the fact that you’re also stuck with the 30 preloaded watch faces, none of which are customizable and only a few of which include useful things like weather data. There is no third-party app ecosystem, for one thing. Huami uses its own Amazfit operating system here rather than the notoriously power-thirsty Wear OS, and how much of a tradeoff that is for you will depend on what kind of a smartwatch user you are. So, how did Huami achieve this? Well, assuming no mysterious price-efficiency breakthrough on the processor - which isn’t listed on the spec sheet - I figure it must be down to the software. You just start thinking of the T-Rex as a regular watch that you’ll need to charge maybe once or twice a month. But battery life like this completely changes the equation. After all, if I need to charge it a few times a week, I might as well just charge it every night - it’s not like I’ll use it for sleep tracking just some of the time. I’ve previously never been too concerned about smartwatch battery life as long as it gets me through the day. The battery capacity of 390mAh isn’t out of the ordinary, and it charges with a magnetic pogo-pin cable like many other watches.ģ0 percent battery left after two solid weeks (There is an always-on option that displays analog or digital time, though it’s off by default and unsurprisingly Huami says it’ll reduce battery life significantly.) It has GPS, an optical heart rate sensor, and pretty much everything you’d expect from a regular smartwatch. To be clear, this isn’t a basic fitness tracker or a hybrid watch - it’s a full-on smartwatch with a nice 1.3-inch OLED screen that I actually kept at a little higher than standard brightness because I found the auto setting too aggressive. A week later, it hadn’t left my wrist but was at 64 percent charge. The day it arrived, I charged it to 100 percent and put it on my wrist. Does it achieve that? Well, I didn’t wear the T-Rex for quite that long, but I can believe it. You’re here to hear about the battery life Huami promises 20 days of use with heart rate monitoring and sleep tracking always on. The cheapest-feeling thing about it is the vibration motor, which doesn’t provide much in the way of satisfying haptic feedback. Huami says it has 12 military-grade certifications that let it be operated in temperatures between minus 40 to 70 degrees Celsius (minus 40 to 158 Fahrenheit) and underwater up to 50 meters (164 feet). As you’d expect from the price, this isn’t the most premium device in the world, but it does feel pretty chunky and pulls off a reasonable G-Shock imitation.