Arriving a tad later than the other two, the iPhone X has been certified by TENAA, which lists its battery and RAM capacities - numbers that Apple rarely talks about. There are some good news and some bad news, neither particularly unexpected. First the good: the X has a slightly bigger battery than the 8 Plus. It's not a huge difference, but keep in mind that the X is more compact than the Plus model. We're about to see if the AMOLED screen is more power efficient than the LCD. Battery RAM iPhone 7 1,960 mAh 2 GB iPhone 8 ...
Source: http://www.gsmarena.com/iphone_x_battery_capacity-news-27455.php
