Fast Charging

Today, almost every serious smartphone on the market comes with one form of fast charging or the other. Phrases like “80% in 30 minutes” or “a full charge in under an hour” have become Mainstays in manufacturer advertising and can be found in every mobile market. Fast charging is a new mobile technology that recently gained traction as a response to increasing phone usage. It is designed to counter the uptime of devices as many people are forced to recharge their phones more than once per day. Fast charging was also born out of necessity because phones are getting bigger and more powerful. Bigger batteries are implemented into these phones as they need a way to keep up with the added power consumption. These large batteries pack a ton of power, and without fast charging, we’d have to wait hours for our phones to top up.

To put it in the most basic way possible, fast charging means increasing the number of watts (W) delivered to a phone’s battery. Normal USB ports send only about 2.5W to the connected device. Fast charging technology raises this number. Modern devices today usually come with 15W power bricks right out of the box. There are even some power-intensive devices that come with 50W, 80W, and 100W chargers available. To you, the end-user, fast charging is simply plugging a compatible fast-charger into your phone. However, on the side of the manufacturers, things are not as straightforward as using a higher-watt power brick.

How  fast charging works

Before we start explaining the fast charging process, you should note that wattage, or power, is computed due to current (A, or amperes) multiplied by voltage (V, or volts). Voltage is the force that pushes current, while currents are simply the amount of electricity being transferred. With this in mind, you should understand that 3A/5V charging will deliver 15W of power.

If you really pay attention to adverts on the market, you’ll notice that manufacturers always flaunt the ability of their devices to do a quick partial charge, such as being able to charge 50-80% of the battery within half an hour. This partial charge speed relies on the way that the rechargeable lithium-ion battery inside phones receives power. If you take your time out to observe how phones charge, you’ll notice that the speed of charging gets progressively slower over time. The charging process in most mobile devices can be divided into three parts, as seen below.

Stage 1 – Constant Current:

In the first minutes of charging, voltage increases towards its peak, while current stays constant at a high level. This is the stage that most manufacturers are worried about; a lot of power is quickly delivered to the device. This is the stage that encompasses the 50% – 80% partial charge.

Stage 2 – Saturation:

In this phase, the voltage proceeds to its peak while the current drops to avoid overloads. This stage is brief and will cover about 10% of the full charge.

Stage 3 – Trickle/Topping:

This is the last phase where the battery is fully charged. In the trickling phase, powers slowly seep in until it reaches 100%. Sometimes in this phase, the power will periodically charge a low “topping” amount as the phone consumes battery.

The amount of time taken and the power transferred in each stage largely depends on what fast charging standard is being implemented. A fast-charging standard is simply an established charging process that corresponds to a particular device, charger, and power output. There are many different fast-charging standards as different manufacturers develop various charging standards capable of varying outputs and charge times.

Fast-Charging Standards

A vast majority of companies have implemented fast charging, and as such, there are quite a few fast charging standards. Below is a list of various fast-charging standards that have been implemented in mobile phones:

USB Power Delivery (USB – PD)

In today’s world, mobile phones use a USB charging cable. Every mobile device, including the Lightning cables for Apple’s iPhones, has a USB connection on the other end. The most common USB over the last two decades is USB 2.0, and it has a maximum power output of 2.5W. When the demand for USBsbto pack more power grew, the USB-PD was introduced. With a USB-PD cable, you can get up to 100W. This standard is used for a wide array of devices, including most flagship mobile phones. The next generation of mobile phones will use USB 4 and will all have USB-PD technology.

Qualcomm Quick Charge

You probably already know this, but Qualcomm chipsets are the most widely used chipset for flagship Android devices. Their latest processors have built-in compatibility with their proprietary Quick Charge standard. Qualcomm’s latest Quick Charge 4+ has a max power output of 100W.

Samsung Adaptive Fast Charging

The name says it all; this standard of fast charging is used by Samsung devices, particularly their Galaxy line. This standard can go up to 18W, and it can automatically adjust charging speeds to preserve the battery’s longevity.

OnePlus Warp Charging

 OnePlus devices use this proprietary Warp Charging standard, which charges their devices up to 30W. This standard is unique because instead of increasing voltage like other fast charging options, this Warp charging uses a full-speed 30W charge.

Oppo Super VOOC Charging

Oppo’s proprietary standard charges their devices up to 50W.

Most other mobile companies don’t have their own fast charging technology. These companies directly use USB-PD or Qualcomm Quick Charge. Others find a way to adapt any of the others to their specific device. Most companies do this, including Companies like Apple, LG, and Google. Even Samsung, outside of their galaxy line, uses these standards for their flagship phones.

 On this list, most standards raise the charging speeds by simply increasing the voltage of their adaptors.  Only Oppo and OnePlus’ standards are different because they opt to increase the current rather than the voltage. To enable fast charging with these devices, you have to use their proprietary cables.