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How fast charging really works

How fast charging really works



Fast charging is a must have feature in today’s phones. It keeps our batteries topped up through busy days. However, there are a variety of different standards . Some only work with specificusb cables and chargers, while others use higher voltages. It can all get a bit confusing, so we’re here to make sense of it.

In a nutshell, fast charging increases the current sent to the battery to fill up its capacity quicker. The basic USB specification only sends 0.5 amps (A) of current using 5 volts (V) for just 2.5 watts (W). Fast charging technologies boost these figures. Huawei’s 10V/4A SuperCharge2.0 produces 40W and Samsung’s 9V/1.7A Adaptive Fast Charging produces 15W of juice. All fast charging services share a common theme — more power.

Fast charging standards explained

USB Power Delivery

USB-PD is the official fast charging specification published by the USB-IF back in 2012. The standard can be used by any device with a USB port, provided its manufacturer includes the necessary circuitry and software. Just like all fast charging standards, USB-PD implements a data protocol to communicate between the charger and phone. This negotiates the maximum tolerable power delivery for both the charger and handset.

USB Power Delivery augments the basic USB charging speeds for up to 100W of output power. The amount of available power is split into different power ratings, which operate at different voltages. The 7.5W+ and 15W+ modes are best for phones, while 27W and above are for laptops and other higher power devices. The standard also supports bi-directional power, enabling your phone to charge other peripherals.

Power output
   (Operating Voltage and Current)

0.5 - 15W

15 - 27W

27 - 45W

45 - 60W

60 - 100W


0.1 – 3.0A

3.0A (15W cap)

3.0A (15W cap)

3.0A (15W cap)

3.0A (15W cap)


1.67 – 3.0A

3.0A (27W cap)

3.0A (27W cap)

3.0A (27W cap)


1.8 – 3.0A

3.0A (45W cap)

3.0A (45W cap)


2.25 – 3.0A

3.0 – 5.0A

Google’s Pixel series utilizes the official Power Delivery specification. Apple also implements the standard in the iPhone 8, iPhone X, and latest MacBooks. Many companies prefer their own proprietary charging standards.

Qualcomm Quick Charge

Qualcomm’s proprietary QC technology was once the default standard in the smartphone industry, as it popularized fast charging before USB Power Delivery. The latest QC4.0 is compatible with Power Delivery, allowing for faster-charging speeds and a wider range of support.



Max Current

Max Power

Quick Charge 1.0




Quick Charge 2.0

5 / 9 / 12V



Quick Charge 3.0

3.6 - 20V (200mV increments

2.5 / 4.6A


Quick Charge 4.0+

3.6 - 20V (200mV increments) QC Mode
  5 / 9V USB-PD Mode

2.5 / 4.6A QC Mode
  3A USB-PD Mode

18W QC Mode
  27W USB-PD Mode

Quick Charge is an optional feature available with Qualcomm’s Snapdragon processors. So just because a phone has a Qualcomm chip doesn’t mean it is Quick Charge compatible. 

Whatever USB-PD charger or QC charger , We could make the proper cable for it , and We develop the 5A fast charging cable for Huawei phone and QC3.0 charger . Welcome to contact us and customize the cable .

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