Illustration of how step-wise charging works under PPS

USB Fast Charging Standards


Fast charging standards on USB date back to 2007. USB-C has only lead to two new standards.



Cross compatibility of USB fast charging standards.


Only a few fast charging standards meet USB-C specifications. But there’s been no issue with those outside of USB-C compliance.


USB-C didn’t introduce fast charging. That technology has been available on USB connections for over a decade. Supporting fast charging, as well as data transfer, was needed for a growing mobile market. Since then many fast charging standards have come and gone. And USB-C has been a big disruptor. But some of the older fast charging standards remain. Most are on the USB-A ports alongside USB-C in power banks and multi-port chargers. A few even creep onto the occasional USB-C port.

Fast charging work by increasing the voltage or current (amps) into your device. This increases the total wattage (volts * amps = watts) beyond what a regular USB charger can do. The device’s battery can charge up to 70% much faster. After that fast charging steps down, to preserve the battery’s lifespan. This is why charging from 0-50% is fast, while 50-100% takes much longer.

USB Power Delivery (USB PD)

USB Power Delivery is a power transfer standard introduced alongside USB-C. It is an open standard maintained by the USB Implementors Forum, as is USB-C and other USB standards. All USB PD is USB-C, but not all USB-C is USB PD.

There are three versions of the standard, with 2.0 and 3.0 being the most common today.

  • USB Power Delivery 1.0: Supports 5V, 12V, and 20V. With up to 2A @ 5V and 5A @ 12V and 20V. The standard also supports some specs which Power Delivery 2.0 and 3.0 don’t allow for. This was done to include USB-C PD chargers that pre-date the standard’s release.
  • USB Power Delivery 2.0: Supports 5V, 9V, 12V, 15V, and 20V. All voltages can go up to 3A. 20V can go up to 5A, providing up to 100W of power.
  • USB Power Delivery 3.0: Supports the same power profiles as USB PD 2.0. It added programmable power supply (PPS). That allows for more efficient charging of lithium batteries.

USB Power Delivery allows for increased power levels. Up to 100W, enough to power a 15-inch gaming laptop. Power flow is also bi-directional. The same port can output or input power, with the connection determining what to do.

The dream of many was that USB PD would become the dominate way to charge all your future devices. As an open standard no one brand would control the market. And one charger to power all your devices. But this isn’t likely to happen. Quick Charge is prevalent in the mobile market. Samsung, Motorola, and Huawei continue to use their own proprietary fast charging standards. Use of USB PD grows, and smaller hardware makers take advantage of its open standard nature. But the other fast charging options aren’t going anywhere.

XKCD Standards

Courtesy of XKCD.com

Programmable Power Supply (PPS)

The programmable power supply protocol was added in Power Delivery 3.0. It is currently uncommon in USB-C chargers and power banks. It allows for small, step-wise changes in voltage and current. This reduces conversion loss during charging. The power transfer is more efficient and lithium batteries endure less heat. Actual charge rates are not better or worst than with other options.

Under PPS charging occurs in two phases. In the first phase the current (amps) is constant, with a gradual increase in voltage. In the second phase the voltage (now at a higher state) is constant, with a gradual decrease in current.

Illustration of how step-wise charging works under PPS

Illustration of how step-wise charging works under PPS

To use PPS both the charger and device must support both Power Delivery 3.0 and PPS. Not all PD 3.0 chargers and devices also offer PPS. The charger handles the step-wise changes once started.

Qualcomm’s Quick Charge 4+, which uses USB-C connectors, supports PPS. Otherwise you’ll need to check both device and charger specs to see if PPS is supported.

Quick Charge (QC)

Quick Charge is the most popular fast charging standard. Developed by Qualcomm, who also holds the largest share of the mobile CPU market. Qualcomm’s SnapDragon CPU is common in Android phones. And they give phone makers the option to add-on the Quick Charge function. The standard has been around for years and supports backwards compatibility. So there is a huge ecosystem available.

Quick Charge 3.0 (QC 3.0)
ZMI PowerPlug Turbo

ZMI PowerPlug Turbo with Quick Charge 3.0 over USB-C

Quick Charge 3.0 is the most popular version of the standard. While several phone makers include it on their USB-C phones it is actually against USB-C specifications. On the charger side it is most often found on USB-A ports. But some chargers also include it on the USB-C port, which again is against specs. The way QC 3.0 uses the data lines for power negotiation disrupts USB-C communication. Since QC is found on dedicated chargers, not computer USB ports, there isn’t an issue in actual usage. It supports up to 18W (5V/3A, 9V/2A, 12V/1.5A).

Not all QC 3.0 devices are created equal. Actual charge rates of QC 3.0 Android phones range from 10-18W, depending on the phone.

QC 3.0 is also mimicked by several other fast charging standard. This is usually allows non-QC chargers and devices to get the fast charging benefits.

Quick Charge 4+ (QC 4+)

Quick Charge 4+ is the newest version of the standard. Few chargers and devices use it for now, but will grow. It is USB-C compliant (unlike QC 3.0) and works alongside USB Power Delivery. All QC 4+ devices are USB PD compatible. As such they can fast charge with either a USB PD charger or a Quick Charge charger.

QC 4+ also supports PPS, from USB PD 3.0. With a QC 4+ charger and device PPS is the preferred charging method used. It offers a fast charge for compatible phones: 27W for PPS, compared to 18W for USB PD or QC 3.0. And the charge is more efficient, with less heat.

Keeping with Quick Charge’s backward compatibility, a QC 4+ device can also fast charge with a QC 3.0 charger. And a QC 4+ charger will fast charge a QC 3.0 device.

Samsung Adaptive Fast Charging (AFC)

Samsung Adaptive Fast Charger

Samsung Adaptive Fast Charger

Samsung developed Adaptive Fast Charging to fast charge their USB-C phones and tablets. And by including a fast charger with their phones they one upped Apple. The latest iPhone still includes a slow, 5W USB power adapter. Samsung’s chargers are USB-A and come with a USB-C to USB-A cable. They support up to 15W (5V/2A, 9V/1.67A).

Samsung AFC works much like Quick Charge 3.0. It is best viewed as a weaker version of QC. It uses the same voltages, but at lower currents which gives the phone less wattage.

As Samsung AFC mimics Quick Charge you can fast charge a Samsung USB-C phone with a QC charger. You could also charge a QC Android phone with a Samsung charger. But it would be a slower change than had you used a QC charger.

Anker PowerIQ 2.0 (PIQ 2.0)

Anker PowerPort II PD

Anker PowerPort II PD with PowerIQ 2.0

Anker’s PowerIQ technology is charger side only. Their tech is only available from their own chargers. It is not installed on any USB-C device. Most other fast charging technology works be being present on both sides of the charge. It supports up to 18W (5V/3A, 9V/2A, 12V/1.5A).

The original PowerIQ (aka PowerIQ 1.0) is not a modern fast charging standard. It supported the older Apple 2.4A standard, but nothing for non-Apple devices. PowerIQ 2.0 mimics Quick Charge 3.0. And as such it is compatible with Samsung phones and Quick Charge enabled Android phones. It also continues to support the older Apple standard. Together it can fast charge a much larger selection of smartphones.

PowerIQ 2.0 is not compatible with Motorola’s TurboPower. And so it won’t fast charge Motorola USB-C phones.

Motorola TurboPower

Motorola’s in house fast charging standard for their USB-C phones. Like Samsung’s it is essentially a weak version of Quick Charge 3.0. Unlike Samsung it is less compatible with non-Motorola fast chargers. It supports up to 15W (5V/3A, 9V/1.6A, 12V/1.2A).

Motorola USB-C phones work well with Quick Charge 3.0 chargers. But they don’t fast charge with Anker PowerIQ 2.0. Nor will they fast charge if Quick Charge 3.0 is on the USB-C port of a charger. Motorola themselves offer two different TurboPower chargers. One is a USB-A charger, requiring a USB-C to USB-A cable. The other is a USB-C charger with a built-in cable.

Huawei SuperCharge

Huawei’s SuperCharge is a different beast from other fast charging standards. Its design makes it the fastest and coolest charger for a phone. But in such a way that makes it incompatible with all other USB-C devices.

SuperCharge increases both the voltage and the current going into the phone. Most other fast charging standards only increase the voltage. This allows Huawei to recharge their phones at either 22.5W (4.5V/5A, 5V/4.5A, 9V/2A) or 40W (5V/2A, 9V/2A, 10V/4A). Much faster than the 15-18W we see on other fast charging standards. The higher output generates a lot of heat. But the power conversion circuits are in the charger, not the phone. This keeps the heat away from the phone, which is better for its battery life.

  • Newer Huawei USB-C phones can only charge at their max draw with SuperCharge.
  • You have to use a USB-C cable rated for 5A. Most are only rated for 3A, and you can’t visually distinguish the difference.
  • A Huawei SuperCharge charger won’t work with any other USB-C device.
  • The 40W version costs so much that it is only available for the Huawei Mate 20 Pro and Honor Magic 2 phones.

A new 20W version is expected in 2019 to support current and future mid to high-end Huawei phones.

OnePlus Dash Charging/Oppo VOOC Flash Charge

OnePlus’ Dash Charging is actually Oppo’s VOOC Flash Charge technology. OnePlus licenses and rebrands it from Oppo. So both OnePlus and Oppo phones will use this fast charging standard.

It has a unique approach to fast charging. It increases the current, rather than the voltage. This has the advantage of less voltage conversion during charging (more efficient). But the higher current generates much more heat. To deal with this the conversion circuits are housed in the charger, not the phone.

  • OnePlus and Oppo phones can only fast charge using their own charger. They can charge with regular USB-C, at a much slower rate.
  • You have to use a USB-C cable rated for 5A. Most are only rated for 3A, and you can’t visually distinguish the difference.
  • The Dash charger won’t work with any other USB-C device.

OnePlus Warp Charge 30

A newer version of OnePlus Dash. It can get up to 30W output. Supported phones can recharge from 0-50% in 20 minutes. And up to 66% in 30 minutes.

It works much the same way, increasing current rather than voltage. The conversion circuits are still housed in the charger, protecting the phone from heat. Like Dash this makes the phone incompatible with other fast charging standards. A Warp Charge 30 charger can used with older OnePlus phones. But will only charge at the phone’s max draw rate.

  • OnePlus Warp Charge 30 phones can only fast charge using their own charger. They can charge with regular USB-C, at a much slower rate.
  • You have to use a USB-C cable rated for 5A. Most are only rated for 3A, and you can’t visually distinguish the difference.
  • The Warp Charge 30 charger won’t work with any non-OnePlus USB-C device.
  • Warp Charge 30 is backwards compatible with older OnePlus phones. But only up to their own draw rate.

Huawei FCP

Before SuperCharge there was Huawei FCP. Developed to fast charge Huawei’s early USB-C phones in 2016. Unlike SuperCharge it is available on non-Huawei chargers. It provides up to 18W, like USB PD and Quick Charge.

The Huawei Mate 9 and P9 used FCP only. But all Huawei USB-C phones that support SuperCharge also support FCP. Consider FCP a secondary fast charging option for newer Huawei phones.

Samsung 2.0A

Before Adaptive Fast Charging Samsung used their own 2.0A fast charging standard. It worked with their micro-USB phones. Providing a faster charge than the then standard USB charger. While Samsung 2.0A can still be found on newer USB chargers it is of no value to their USB-C phones.

Apple 2.4A

Newer Apple iPhones and iPad Pros use USB Power Delivery with their newer mobile devices. But before that they had their own fast charging standard, known as Apple 2.4A. It is the reason you see 5V/2.4A as a common power profile on USB-A chargers. But note that not all 5V/2.4A USB-A chargers support Apple 2.4A. The standard was developed to charge the iPad. It was then included in the iPhone 4. It has continued down the iPhone line, including today’s models.

For an older standard it charges newer iPhones well. Apple 2.4A provides up to 10.5W. Newer iPhones can get up to 15W from USB PD. But the difference between the two standards narrows as the phone charges.

Apple 12W USB Power Adapter

Apple 12W USB Power Adapter, the original Apple 2.4A charger

iPhone 8 @ 0%

  • USB PD: 11W
  • Apple 2.4A: 9.4W

iPhone 8 @ 10%

  • USB PD: 10.5W
  • Apple 2.4A: 9.4W

iPhone 8 @ 20%

  • USB PD: 12W
  • Apple 2.4A: 9.2W

iPhone 8 @ 30%

  • USB PD: 8.5W
  • Apple 2.4A: 8.5W

By 70% all fast charging is disabled on an iPhone. If you regularly charge your iPhone from a low battery state then USB PD wins. But if you typically top off throughout the day then Apple 2.4A work just as well.

Apple 2.4A can be found on both USB-A and USB-C chargers. And doesn’t appear to be against USB-IF standards. They have certified chargers with Apple 2.4A on the USB-C port. A USB-C charger offering both USB PD and Apple 2.4 can fast charge and iPhone from the 4 to the XS. With the use of a USB-C to Lightning cable.

Battery Charging Revision 1.2 (BC1.2)

Battery Charging Revision 1.2 is the original USB fast charging standard. Developed in 2007 by the USB-IF. It better supported powering various USB devices in a growing mobile market. All USB charging ports today include BC1.2. Any USB port without BC1.2 (most often found on computers) are limited to 2.5mA (0.0025A) current.

There are three versions of BC1.2:

SDP (Standard Downstream Port)

  • Supports data over power
  • Limits current to 0.5A
  • Found on PCs

DCP (Dedicated Charging Port)

  • Doesn’t support data transfer
  • Supports current beyond 1.5A
  • Found on USB chargers

CDP (Downstream Port)

  • Supports both data transfer and high-current charging
  • Found on USB hubs

Cross Compatibility of USB Fast Charging Standards

 

USB Power Delivery

Quick Charge 4+

Quick Charge 3.0

Samsung Adaptive Fast Charging

Anker PowerIQ 2.0

Motorola TurboPower

Huawei SuperCharge

OnePlus Dash Charging

USB Power Delivery

Quick Charge 4+

Quick Charge 3.0

Samsung Adaptive Fast Charging

Anker PowerIQ 2.0

Motorola TurboPower

Huawei SuperCharge

OnePlus Dash Charging


Fast Charging Standards & USB-C Specifications

USB Power Delivery, Quick Charge 4+, Apple 2.4A, and BC1.2 all meet USB-C specifications. USB PD and BC1.2 were both created by the USB-IF. Quick Charge 4+ uses USB-C’s communication lines, where QC 3.0 hijacked the USB data lines. And Apple 2.4A doesn’t interfere with USB data.

The other fast charging standards are outside of USB-C specifications. That means their inclusion on a USB-C port is against USB-IF compliance standards. As USB-C is an open standard there’s no punishment for doing so. But such chargers wouldn’t meet USB-IF certification. In 2016, some USB-C chargers started offering Quick Charge 3.0. A few USB-C focused engineers warned against this practice. They cited the USB-IF specifications. But the predicted consequences were vague. As it turned out, nothing bad happened. Since then several chargers have operated this way, against specs. But there have been no reports of real world issues.

If you’re a stickler for meeting USB-C specifications then you should stick with USB PD and QC 4+. If you’re more pragmatic then consider yourself informed on the matter.