When consumers look to buy a new smartphone, there are usually four fundamental components which are most sought after. A good screen, a fast processor, high quality cameras, and a good battery experience. As our lives and workloads have become increasingly dependent on our phones, companies are fitting their latest models with larger batteries by the year.

Take the original iPhone, as an example. When it was unveiled in 2007, it shipped with a 1400mAh battery. Just for comparison’s sake, take a look at the battery capacities of the latest Android phones. Most, if not all are well north of 4000mAh, with a few hitting 5000.

So, as the years went on, all four pillars of a good smartphone were pushed to their limits. Displays became brighter, sharper, and more responsive. Cameras began challenging and very quickly surpassing point-and-shoots. They were doubling in performance nearly every year, but only HALF of the battery experience really improved. While yes, batteries were magnitudes bigger than they used to be, they still charged at absolutely paltry rates.

Slow charging was completely fine for us when our dependence on phones was nothing more than texting, calling, and the occasional webpage. However, with the rapid evolution of smartphone capabilities and our increasing reliance on them for everything from work to entertainment, the limitations of slow charging became glaringly apparent. Waiting for hours to get a decent charge became a bottleneck in our fast-paced lives, leading to the birth of a new technological frontier: fast charging.

How charging works 101

Let’s start at the very beginning. Every single smartphone on this planet contains a battery.

To put it simply, a Lithium-ion battery works through the movement of lithium ions between the positive and negative electrodes during the charging and discharging cycles.

  • Anode (Negative Electrode): Composed of graphite, the anode hosts lithium ions during the battery’s discharge cycle, allowing them to move from the anode to the cathode through the electrolyte.
  • Cathode (Positive Electrode): Typically made from a metal-oxide, the cathode receives the lithium ions during a discharge cycle.
  • Electrolyte: This conductive medium, often a lithium salt dissolved in a solvent, facilitates the flow of ions between the anode and cathode. It is essential for ion movement while preventing direct contact between the anode and cathode to avoid short circuits.
  • Separator: Acting as a permeable membrane, the separator physically separates the anode and cathode, preventing short circuits while allowing the passage of lithium ions.

What is fast charging

To put it simply, fast charging is simply charging a device with more power, or increasing the wattage delivered to the device’s battery. The USB 2.0 standard makes all cables adhering to the standard send 2.5W of power, aka a negligible amount of power. Current generation SLOW charging is around 5-10W, while fast chargers range from 25 to 100W.

To us, fast charging is finding a brick with ’65W’ written on it, and plugging our phones into it. However, there is a lot that goes on beneath the surface

How

Before I go any further, the power which a device charges with is measured by multiplying current with voltage (W = V * I). Current is the amount of electric current delivered, while voltage is the electromotive force that drives the current.

If you have ever read through the spec sheets companies give alongside their devices and direct your attention to the ‘battery’ section, the first thing you’ll find is that they NEVER boast about full charge time, instead opting to advertise their device’s ability to charge from 0 – 80%. The reason behind this is that charging is NOT a linear process. A fact which is very easily observed when charging your own devices. Between 0 to 80%, the device will increase its voltage until charging at or around its peak potential wattage. As the device approaches 80%, the device accepts less current, while still keeping its voltage high. This is done to prevent overcharging and overheating, both very detrimental to the lifespan of the battery.

Differing standards

As is the case with any new feature, every major smartphone manufacturer has introduced their own flavour of fast-charging. They all work relatively in the same way, as I explained above.

Here’s a few examples of what I’m on about: OnePlus has Warp Charging; Qualcomm has Quick Charge; Oppo has Super VOOC. All of these standards share the same foundational principles but suffer from a lack of cross-compatibility. Power bricks without certification from these companies won’t charge devices adhering to these standards beyond 10W.

USB to the rescue!

While yes, USB and I haven’t always seen eye to eye with their garbage naming conventions for their data transfer standards, (looking at you, USB 3.2 Gen 2), there is a reason that they are the industry standard.

Amidst the chaos of varying standards, USB Power Delivery (USB-PD) emerges as the knight in shining armour. Unlike proprietary standards, USB-PD is a universal standard designed for fast-charging (key word UNIVERSAL), implementable in any USB device. For us, this means a plethora of options when choosing power adapters, breaking free from the constraints of manufacturer-specific standards.

The latest USB PD revision can deliver a staggering 240W, finally allowing even the most power-consuming laptops to join in the fun.

Summing it up

There you have it – fast charging in a nutshell. A quick look at what really goes on when the USB cable is plugged into your phone, and how it’s evolved over the last 15 years.

Oh, and don’t forget USB coming to our rescue (again) amongst a fog of stupid proprietary standards.