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What is fast charging and how does it work?

What is Fast Charging and why would you want it?

You might not realise it, but chances are, if you’re rocking a modern smartphone like the Samsung Galaxy S9, LG G7, Moto G6 or iPhone X then it already supports some form of fast charging.

If you’re unfamiliar with the technology, here we’ll explain what it is, how it works, and which smartphone manufacturers use which standard.

How does fast charging work?

The fundamental components concerned with powering your smartphone are the battery, power adapter, charging cable and the charge controller – the chip responsible for regulating the flow of power in and out of the battery. The premise of fast charging a smartphone (or tablet or laptop) hinges on the rate of power flow possible versus the limitations of the components and the safety restrictions in place.

Related: Best smartphones

Different standards facilitate different voltage (V), current (A) and wattage (W) values, which paired with the capacity of the battery they’re charging up, dictate the fast charging speeds that are possible.

Different types of fast charging

Adaptive Fast Charging

Samsung’s Adaptive Fast Charging tech has served as one of the longer-standing players in this roundup. Originally introduced on 2014’s Samsung Galaxy Note 4, it has an output of 5V and 2A (10W). It’s one of the slower fast-charging solutions out there.

The 3500mAh battery inside 2018’s Samsung Galaxy S9 Plus reaches over 40% charge in 30 minutes and completes a full charge at around 1hr 35mins using Adaptive Fast Charging.

  • Exclusively used by Samsung

Samsung Galaxy Note 9 fortnite

Anker PowerIQ

If you want to talk about adaptability then Anker’s PowerIQ standard is one to watch. The company may have established itself by creating super-sized portable battery packs for smartphones and other personal electronics, but it’s now investing more time into how these devices charge.

Related: iPhone 9

PowerIQ is designed to automatically detect and scale the voltage output from one of the company’s supported power sources (such as the PowerCore II line) for the optimum rate of charge into your chosen device. It’s assisted by the company’s VoltageBoost technology, which ensures stable power delivery regardless of the cable you use.

The latest version of the standard, PowerIQ 2.0 can deliver up to 18W of power. Anker quotes a total charge time from one of its compatible battery packs into a Samsung Galaxy S8 (which features a 3000mAh battery) at 1hr 30mins.

  • Works with most modern devices 

Fast Charge (formerly Dash Charge)

One of the biggest selling points of the OnePlus 3 was the introduction of the company’s Dash Charge technology: a new standard that still trumps practically every other smartphone-centric fast-charging standard on the market in terms of speed and implementation.

A fundamental difference between Dash Charge and its competitors is that heat build-up happens almost exclusively within the power adapter itself. Typically, fast charging causes your phone’s battery or the charge controller and surrounding components to heat up, but OnePlus’ solution leaves the phone perfectly cool, even if you’re using it while it charges.

After some minor legal issues, OnePlus recently rebranded Dash Charge to the more generic-sounding Fast Charge, but the technology behind it is no less potent. With an output of 5V and 4A (equalling 20W), OnePlus’ Fast Charge technology can juice the OnePlus 6‘s 3300mAh cell up to 60% charge in 30 minutes, which has earned the brand the suitably catchy tagline of “a day’s power in half an hour.”

  • Exclusively used by OnePlus

Related: Best Android phones

Quick Charge

If you’ve heard of any form of fast charging technology, it’s most likely chip-maker Qualcomm’s Quick Charge standard. Chances are you’ve owned a smartphone powered by a Qualcomm processor, which means it’s supported some level of Quick Charge – although some phones such as the Samsung Galaxy S6 can support Quick Charge without relying on a Qualcomm processor, so long as they feature a Quick Charge-compliant charge controller.

Quick Charge is bundled as a supported feature on every one of the company’s current-generation mobile processors, while the age of the chip also dictates which version of Quick Charge is supported.

Quick Charge 1.0 was originally introduced in 2013 on the Snapdragon 600, supporting 5V at 2A (10W). Quick Charge 2.0 then appeared on the majority of Qualcomm’s 2015 mobile processors, offering support for a wider variety of voltages and amperages, and promising up to 18W of power delivery.

Quick Charge 3.0 offered up to the same output a year later, but supported variable voltage outputs under the INOV (Intelligent Negotiation for Optimum Voltage) brand name. It was able to deliver power in 200mV increments, ranging from 3.6V up to 20V at 2.6A or 4.6A. Similarly to Anker’s PowerIQ standard, this allowed the charging system to dynamically alter the rate of charge for the most efficient rate of power delivery on a device-by-device basis.

Although Qualcomm announced Quick Charge 4.0 alongside the arrival of its then-flagship processor, the Snapdragon 835, we never really saw devices or power adapters that offered support for the standard. It wasn’t until Qualcomm introduced Quick Charge 4+ a few months later that we started seeing it popping up on market-ready handsets.

QC 4+ boasts all the benefits of QC 4.0, such as USB-C and USB PD compliance at 5V and 9V and support for variable voltage output in 20mV increments between 3V and 5.9V or 3V to 11V using the USB PD 3.0 PPS (Programmable Power Supply) spec. Support for 3.6V to 20V in 200 mV increments is also on-hand when using a Quick Charge-compliant adapter, and that’s all set at 3A via USB PD or 2.5A or 4.6A when using Quick Charge.

In addition, the ‘plus’ elements of the Quick Charge 4+ standard take the form of improved, faster, more-efficient charging called Dual Charge. These include intelligent thermal balancing, which is designed to distribute heat as evenly as possible so everything remains cool, and  advanced safety measures in place to prevent overheating or short circuits as well.

  • Most commonly used by HTC, Motorola and Sony

Sony Xperia XZ3 standing

Pump Express

MediaTek’s answer to Quick Charge goes by the name of Pump Express, and like Quick Charge we’ve reached the fourth iteration of the technology. It’s available across a range of the company’s chipsets, can deliver up to 5A of current and, like QC 4.0/4+, also adheres to the USB PD 3.0 standard.

  • Most commonly used by Huawei/Honor, Motorola and Sony


If you’ve got all of the components necessary, TurboPower can deliver up to 5V at a maximum 5.7A for a theoretical 28.5W of power. Motorola sells a TurboPower 15 and TurboPower 30 adapter, the latter of which offers the fastest potential charging speeds; it promises 15 hours use after just 15 minutes charge time. TurboPower 30 is supported by the company’s Moto Z line over USB-C.

Like Samsung’s Adaptive Fast Charging tech, TurboPower also plays nice with Qualcomm’s Quick Charge 2.0 standard

  • Exclusively used by Motorola


Huawei introduced its own fast charging technology alongside its Huawei Mate 9 phablet. SuperCharge follows a similar setup to that of OnePlus’ Fast Charge tech, with a design that keeps the phone as cool as possible during charging. Huawei’s technology scales between 5V and 2A, 4.5V and 5A or 5V and 4.5A, depending on the device/charging conditions.

It requires a certified cable and battery in order to be properly supported.

  • Exclusively used by Huawei/Honor


As you may have already noticed, USB PD has cropped up a few times within this roundup among other fast charging technologies. USB PD – short for Power Delivery – is a USB power standard that facilitates fast charging. It’s supported by a gamut of manufacturers, too, but in the smartphone space it’s been popularised by the likes of Apple and Google.

Related: iPhone XS

USB PD 3.0 is capable of supporting a maximum theoretical output of a whopping 100W. Depending on the target output wattage, USB PD scales the voltage and amperage accordingly. You can expect 3A at up to 15V or between 3A and 5A at up to 20V for output requirements between 60W and 100W.

  • Most commonly used by Apple and Google

VOOC Flash Charge

Remember that we mentioned OnePlus’ Fast Charge tech was in a league of its own? Technically, that isn’t true: the technology actually originates from Chinese mobile giant, Oppo. The company’s VOOC (Voltage Open Loop Multi-step Constant-Current Charging) Flash Charge standard is the same as Dash/Fast Charge (Oppo licensed the technology to OnePlus), with a 5V, 4A, 20W output that rapidly charges its phones while keeping them cool.

Oppo’s head-turning 2018 flagship, the Oppo Find X, is the latest handset to tote VOOC Flash Charging; however, there’s actually a sizeable back catalogue of devices that accommodate the standard. The Find X boasts a large 3720mAh battery but can be completely filled from empty in 1hr 40mins using VOOC.

Those lucky enough to get ahold of the rare Oppo Find X Lamborghini Edition will also benefit from the added value of the company’s improved SuperVOOC charging standard, which promises to juice up the phone’s equally sizeable battery to full in an astonishing 35 minutes.

  • Exclusively used by Oppo

Is fast charging a feature you require on a phone? Let us know @trustedreviews

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