About iPhone X, Wireless Charging and Fast Charging

6 min readNov 7, 2017

The iPhone X release marks the 10 year anniversary of the most important tech revolution since the Internet. It has changed the way we live and become the most important object we possess… for long as it has battery. Charging has definetely become a big thing in our busy lives and juicing up technologies have proliferated accordingly.

Qualcomm Quick Charge, Dash charge, Apple Fast charging… Oh, and then comes wireless charging, too. Erf.

How does it work?

How fast is it?

As this year also marks the launch of a first generation of iPhones supporting both fast charging and wireless charging, let’s explore what each technology entails, in perspective with USB-C.

Wireless Charging

A bit of history.

Wireless charging is probably one of the most intriguing new technologies of the past decade. Why? Because it’s actually pretty old. While its practical application is new, wireless electricity transmission was actually first conceptualized by Micheal Faraday in 1821 (otherwise known as creator of the electric motor). Obsessed by the concept, Nicolas Tesla even ruined himself building a laboratory in Warenclyffe to work on it.

Practically speaking, if electricity oscillates (= vibrates) in a wire coil, it emits an electromagnetic field. If another wire coil is placed nearby, it will capture that electromagnetic field and convert it into electricity. Two important conditions are required to make this happen:

The distance between the two coils needs to be small and free of any obstacle that would block the electromagnetic field. Air, wood, ceramic, plastic or glass is fine. Aluminum is not. This explains why the new iPhone has a more delicate glass body instead of the aluminum body we have seen since the iPhone 5.
Control the oscillation of the electricity in the emitting coil. The recent progress in electronics finally allow for perfect control and dialog between the emitting and receiving coil. The solution to a nearly 200 years old fantasy resides in a microscopic piece of silicon.

How fast is wireless Charging?

“Only 60–70% of the energy from the emitting coil is converted into electricity while the rest is dissipated in heat.”

The current state of wireless charging only allows for average charging speed. The reason is all magic comes with a price, or in this case efficiency: only 60–70% of the energy from the emitting coil is converted into electricity while the rest is dissipated in heat. In other words, if the charging speed increases, the device will get hot. And the last thing you want while charging a phone is heat — ask Samsung.

Apple is currently pushing technology to the edge with its fast wireless charging, available on iPhone 8 and iPhone X through software update in January or February next year.

Qi Protocol

Pronounced (/tʃiː/ CHEE) the word stands for “energy flow” in Chinese. It is also the name for the standard protocol in wireless charging, or the USB of wireless charging. But what is the utility of a standard protocol for something that has by definition no physical port… Well, remember the oscillation? For stable charging, synchronisation is key. Both the charger and the device need to communicate and the most spoken wireless language today is Qi. Apple initially created its own wireless protocol for the Apple Watch but dropped it with the current generation of iPhones, all Qi compatible (Yay!).

Fast Charging

How it works.

This year’s generation of iPhone comes with Fast Charging functionalities e.g. charging your phone from 0 to 50% in half an hour or less. Such boost is particularly useful when you need a charge, asap.

Before digging any further, it is actually important to understand the basics of modern battery charging.

Batteries are similar to suitcases: the more you pack in, the harder it is to pack in any more; and the longer it takes. A complete charging cycle (from 0 to 100%) happens in 2 phases:

1. First is the CC phase (for Constant Current) , from 0 to ±80%. The CC phase is throwing hoodies and pants in the suitcase. Packing a lot, fast.
2. The second phase is the CV phase (for Constant Voltage), filling empty slots with socks and small items, making the most out of a given space.

The first phase is the most energy intensive and this is where fast charge will make a difference. After a specific handshake to ensure both the charger and the smartphone are compatible, the charger will provide more power (bigger hoodies), completing the first phase faster. The second phase lasts just as long with or without fast charging technology.

iPhone X vs Samsung S8 fast-charging : a comparison

Many smartphone manufacturers have created their own fast charging technology, examples including: Samsung Fast Charge, OnePlus Dash Charge, Qualcomm Quick Charge (Xiaomi, LG) /… Those technologies are not necessarily intercompatible but the underlying principle remains the same: bigger hoodies in the suitcase. Only the handshake differs.

As Line Dock is already fully compatible with the iPhone X in both wireless charging and fast charging, we took advantage of its massive and smart power supply to test two major rivals: the iPhone X and the Samsung Galaxy S8.

The Samsung Galaxy S8 was charged using the original Samsung cable connected to one of the USB 3/Qualcomm Quick Charge 3 port of Line Dock. The iPhone X was charged using an Apple Lighting to USB-C cable (purchased separately) connected to one of the USB-C port of Line Dock, delivering up to 100W of charge.

Overall, the iPhone X was well ahead of its competitor for the first hour of charging, with 82% of battery fully loaded against “only” 69% for the Samsung Galaxy S8. And yes, with a powerful enough charger/device, you can get a nice 53% of charging in just 30min, as Apple claims it. In the second phase of charging cycle, the S8 recorded faster charging speed though, reaching 100% of charge in 01h26 minutes versus 01h56 minutes for the X.

And here is USB-C.

Now comes the USB Power Delivery, the official charging protocol for the new USB-C standard. This protocol is universal in two aspects:

It is a common agreement (finally) between most of the biggest players in the industry: Google, Apple, Qualcomm.
It is not limited to smartphones. Most high-end laptops now offer USB-C ports and have USB-C (Power Delivery) chargers. The Nintendo switch uses the same technology while the entire electronic market is shifting to this unique port.

The USB-C protocol is supported by the new generation of iPhones even though Apple has kept its original Lightning port. To take full advantage of the charging capacity, a USB-C to Lightning port is required, together with a USB-C charger (29W at least).

Why should you care?

On the path to an interconnected tech scene, a single connector that can carry data, power (up to 100W) and video is more than likely to take over any fast charging alternative, what’s more, if that precise protocol is backed by Apple, Google and Qualcomm. Alternative solutions will progressively fade away, leaving room for two trendsetters: wireless charging on one hand, and USB-C on the other.

We’re excited to see that Apple finally made a more concrete move towards fast and wireless charging. Both technologies will surely change the way we power our devices forever.

So Apple, shall we expect an iPhone 11 in both USB-C and wireless charging?