There was nothing relative to”fast”with some ambiguity there, iPhone that”comes with the charging adapter as compared to the fast charging means whether there”has meaning. In this regard, the 2014 and the launch of the iPhone 6 or later model,faster charging means is provided.
Most of the iPhone comes with charging adapter(AC-to-USB adapter), the maximum output is 5V×1A=5W in. However, iPhone 6 is up to 1. 4A of inputs, more output is large, the optional power adapter if you use a 5 V×1.4 A=7W charging is possible. iPhone 6 Plus is up to 2. 0A of inputs, 5 V×2.0 A=10W and the faster you can charge.
8/8 Plus since the iPhone is”USB PD”correspond to the conditions is favorable. USB PD response of Type-C ports charging adapter and USB to Lightning cable(Type-C port and Lightning port equipped with cable)requires a maximum 18W and faster charging is possible.
That is, the faster the charging, the output is large, the USB port comprising a power adapter(or mobile device)is required. USB standard, the 5V is constant, the amperage is 2. 0A or more, preferably 2. 4A more than the world. High amperage corresponding to the Lightning cable also needed, the MFi(Made for iPhone)logo posted on the product if it is not a problem.
So the next charging speed if we aim for power adapter/mobile battery and the cable to the USB PD uniform immediately. In 2017 the launch of the iPhone X/8/8 Plus or later model, if the status quo is the fastest of charge of the environment is available. Incidentally, the iPhone 11 Pro/Pro Max is the fastest of charge of the environmental standard, the”faster”charging environment does not exist.