Quick Charge

Quick Charge (QC) is a proprietary battery charging protocol developed by Qualcomm, used for managing power delivered over USB, mainly by communicating to the power supply and negotiating a voltage.
Quick Charge is supported by devices such as mobile phones which have Qualcomm chipsets, and by some chargers; both device and charger must support QC, otherwise QC charging is not attained. It charges batteries in devices faster than standard USB allows by increasing the output voltage supplied by the USB charger, while adopting techniques to prevent the battery damage caused by uncontrolled fast charging and regulating the incoming voltage internally.
Most chargers supporting Quick Charge 2.0 and later are wall adaptors, but it is implemented on some in-car chargers, and some power banks use it to both receive and deliver charge.
Quick Charge is also used by other manufacturers' proprietary rapid-charging systems.
Details.
Quick Charge is a proprietary technology that allows for the charging of battery-powered devices, primarily mobile phones, at power levels exceeding the 5 volts at 2 amps, thus 10 watts allowed by basic USB standards —not considering the USB Power Delivery (USB PD) standard—while still maintaining compatibility to existing USB wires.
The elevated voltages allow for pushing higher amounts of power (wattage) through the cable's copper wires without further heating them up and risking heat damage, since heat in the wire is solely caused by the electrical current.
Another benefit of the elevated voltage, as described in , is its improved ability to pass through longer USB cables due to its compensation of voltage drops from wires with higher resistances.
Numerous other companies have their own competing technologies, including MediaTek Pump Express and "OPPO VOOC" (licensed to OnePlus as "Dash Charge"), the latter of which elevates the current rather than the power supply voltage to reduce heat from internal voltage regulation, but relying on thicker USB wires to handle the current without overheating, as described in .
Though not publicly documented, the protocol (e.g. voltage negotiations between device and charger) has been reverse-engineered, and a custom voltage can be manually requested from the charger using a "trigger circuit" that simulates the negotiation to an end device.
To use Quick Charge, both the host providing power and the device must support it. In 2012, the USB Implementers Forum announced that the USB Power Delivery (USB PD) standard had been finalized, allowing for devices to draw up to 100 watts of power over supported USB ports. This new technology was first used in a Xiaomi Mi Mix 4 prototype that charged from 1% to 100% in 17 minutes.
Quick Charge 2.0 introduced an optional feature called Dual Charge (initially called Parallel Charging), using two PMICs to split the power into 2 streams to reduce phone temperature.
Quick Charge 3.0 introduced "INOV" ("Intelligent Negotiation for Optimal Voltage"), Battery Saver Technologies, HVDCP+, and optional Dual Charge+. INOV is an algorithm that determines the optimum power transfer while maximizing efficiency. Battery Saver Technologies aims to maintain at least 80% of the battery's original charge capacity after 500 charge cycles. Qualcomm claims Quick Charge 3.0 is up to 4–6 °C cooler, 16% faster and 38% more efficient than Quick Charge 2.0, and that Quick Charge 3.0 with Dual Charge+ is up to 7–8 °C cooler, 27% faster and 45% more efficient than Quick Charge 2.0 with Dual Charge.
Quick Charge 4 was announced in December 2016 alongside the Snapdragon 835. Quick Charge 4 includes HVDCP++, optional Dual Charge++, INOV 3.0, and Battery Saver Technologies 2. It is cross-compatible with both USB-C and USB PD specifications, supporting fallback to USB PD if either the charger or device is not compatible. However, Quick Charge 4 chargers are not backward compatible with Quick Charge. It also features additional safety measures to protect against over-voltage, over-current and overheating, as well as cable quality detection. Qualcomm claims Quick Charge 4 with Dual Charge++ is up to 5 °C cooler, 20% faster and 30% more efficient than Quick Charge 3.0 with Dual Charge+.
Quick Charge 4+ was announced on June 1, 2017. It introduces Intelligent Thermal Balancing and Advanced Safety Features to eliminate hot spots and protect against overheating and short-circuit or damage to the USB-C connector. Dual Charge++ is mandatory, while in prior versions Dual Charge was optional. Unlike Quick Charge 4, Quick Charge 4+ is fully backward compatible with Quick Charge C 2.0 and 3.0 devices.
Quick Charge 5 was announced on July 27, 2020. With up to 100W of power, on a mobile phone with a 4500mAh battery, Qualcomm claims 50% charge in just 5 minutes. Qualcomm announced that this standard is cross-compatible with USB PD PPS programmable power supply, and that its technology can communicate with the charger when charging double cells and double the voltage and amperage out. For instance, a single battery requests 8.8V of power. The dual cell can then ask the PPS charger to output 17.6 volts and split it in half to the two separate battery, pulling 5.6 amps total to achieve 100 watts. The first phone with this technology was the Xiaomi Mi 10 Ultra.
Quick Charge for Wireless Power.
On February 25, 2019 Qualcomm announced Quick Charge for Wireless Power. Quick Charge for Wireless Power falls back on the Qi standard by the Wireless Power Consortium if either the charger or device is not compatible.
Other charging protocols.
Quick Charge-based protocols.
Note: These are compatible with Quick Charge-enabled chargers
Comparison to Pump Express.
MediaTek Pump Express is the charging technology of Qualcomm's main chipset vendor competitor MediaTek.
The 2014 and 2015 versions of Pump Express, "Pump Express Plus" and "Pump Express Plus 2.0", competing with Qualcomm Quick Charge 2.0 and 3.0 respectively, differ by communicating voltage requests to the charger using current modulation signals through the main USB power lanes ("VBUS") rather than negotiating through the USB 2.0 data lanes.
MediaTek Pump Express Plus (counterpart of Quick Charge 2.0) supports elevated voltage levels of 7, 9 and 12 volts, the first of which is not supported by Quick Charge 2.0.
Like its counterpart Quick Charge 3.0, Pump Express Plus 2.0 supports finer-grain voltage levels. Those of Pump Express Plus 2.0 are between 5 volts and 20 volts, with half a volt between each step (5.0V, 5.5V, 6.0V, …, 19.5V, 20.0V). However, the wider voltage range of Quick Charge 3.0 starts at 3.6 volts with 0.2 volts between each step and goes up to 22 volts (3.6V, 3.8V, 4.0V, …, 21.8V, 22V).