The battery life of a mobile device always plays one of the priority roles when choosing a new smartphone. The Phone Arena Internet resource has the opportunity to conduct a test for autonomy among the flagship models of different manufacturers. The test participants were: Samsung Galaxy S8 +, Apple iPhone 7 Plus, Samsung Galaxy S7, Samsung Galaxy S7 Edge, Apple iPhone 7, Google Pixel XL, OnePlus T3 and Huawei P10. The best result was the iPhone 7 Plus, its battery life was 9 hours 5 minutes. Following him was the Galaxy S8 +, but not with such a high rate – 8 hours. The autonomy of other flagship smartphones can be found below. The test was conducted in normal use with a brightness of 200 nits. Recall, the Apple iPhone 7 Plus is equipped with a 5.5-inch TFT IPS display FullHD-resolution (1920 × 1080 pixels, density 401 ppi), a 4-core proprietary processor A10 Fusion 64-bit architecture and a battery capacity of 2900 mAh. The Samsung Galaxy S8 + participating in the test had a 6.2-inch Super AMOLED display with Quad HD + resolution (2960 × 1440 pixels, density 529 ppi), a 3,500 mAh battery and Samsung Exynos 8895 proprietary chipset, made using the 10-nm process technology, which provides 27% more high performance and 40% reduced power consumption compared to solutions made using the 14-nm process technology. Despite the large battery capacity and more energy-efficient processor, the Galaxy S8 + still consumes charge faster due to the large display.