The T-Rex Dual Solar is designed to deliver maximum battery life for outdoor sports on multi-day trips, without having to recharge it. Amazfit claims up to 180 days of battery life, in certain conditions specified as being linked to the Battery life section. To develop this system, the watch is based on a T-Rex Ultra 2, from which it takes the features.
In terms of battery life, Amazfit provides a range of values depending on the usage mode. In standalone GPS, the advertised battery life increases from 47 h to 58 h with solar charging. In automatic mode, it goes from 25 days to 34 days, and then, with the extreme outdoor mode, from 40 days to 47 days. Finally, the longest claim reaches 180 days in extreme outdoor mode, with 50,000 lux of sunlight.
The text also includes an important limit on how solar works: it does not state that the front and rear panels can increase battery life at the same time. On the contrary, it specifies that the operation is necessarily “either one or the other”, and that the rear panel “is useless” when the watch is worn on the wrist. This constraint explains why charging would not depend solely on the presence of solar power, but on how it is oriented during use.
