Stefan Mileschin

While the iPhone X is already an expensive device, prospective owners will have to pay even more for fast charging: you'll need to spend at least $74 on a special charger and a USB Type-C Lightning cable for the privilege. It all comes down to the fact that Apple's Lightning protocol doesn't support the wattage, voltage, and amperage needed to enable true fast charging when it's connected to a standard USB Type-A port on the other end of the cable. Thanks Reimu. Because the Lightning cables that Apple includes in the box with every iPhone have a USB Type-A connector on the end that plugs into the charger, they don't possess the pins needed to facilitate USB Power Delivery. Namely, the two channel configuration pins, CC1 and CC2. This is why the new iPhone models need a special cable -- one that uses USB Type-C on the charger side -- to take advantage of USB-PD 2.0 and enable fast charging.

http://www.hardocp.com/news/2017/09/...o_fast_charge/