• Subir Biswas

What is Fast Charging, and how does it Works for Mobile Phone.

Today for all mobile phones, specifically smartphones packaged with the first charging tag. Moreover, for a few companies "First Charging" is the key selling point. But what is Fast Charging and how does it work in real life? What is Quick Charge 3/4? We will get to know all of these here.


What is Fast Charging?

Nowadays most of the people are using a smartphone to communicate and for entertainment purposes. And a lot you can do using your smartphones. But, remember when you want a device which can perform very smoothly and quickly, the device needs more power. Means, the performance is proportional to the power. But for a smartphone, as it is mostly one handed device, based on current battery technology no manufacturer can provide a battery which can run for one day after a heavy use (more than 24 hours operations with keeping the display ON). As a result, when the battery drains, users need to pump it up. But on busy days, no one has much time to keep the phone in charge for a long time. Therefore, the solution introduced to charge the battery faster than the normal charging rate, This is double or triple or sometimes 10 to 15 times of the normal USB charging rate (2.5W).


Understand the Fast Charging Process.

Before we go further just to make it very clear about a basic electrical formula.

Wattage / Power (W) = Current (A) x Voltage (V)

Current is the amount of electricity flowing from the battery and Voltage is the force of the current. Watts are Current multiplied by Voltage. For example a USB Type 2 Port can deliver 0.5A current with 5V which means, a USB Type 2 can deliver 2.5W (0.5x5) of Power.


To make a device charge faster, most manufacturers either boost the current or boost the voltage in order to increase the amount of power. However, one thing you might have noticed is that the batteries are getting charged around 50% within half an hour or less. This is because of the charging regime of the internal lithium-ion battery inside phones. The charging speed will gradually be reduced with the time or SOC (state of charge) or percentage of charge.

Charging Lithium-ion Batteries

The charging process is divided in 4 stages.

Stage 1 - Constant Current (CC):

In this stage the voltage will increases by keeping the current contact to boost the battery voltage quickly. This stage is where most of the power will be delivered through the charger. Remember the heat generation on the battery will be higher in this stage.

Stage 2 - Constant Voltage (CV):

At this stage the voltage will freeze at peak level (for most of the case 4.2V), but the current will start to reduce, to slow down the charging and of course the temperature of the battery. Full charge occurs when the battery reaches the voltage threshold and the current drops to 3 percent of the rated current.

Stage 3 - Ready or Charge Terminate:

Once the charging current drops to 3 percent of the rated current, the charging will stop and the battery voltage begins to drop as well. This eases the voltage stress from the battery.

Stage 4 - Topping Charge:

When lithium-ion batteries must be left in the charger for operational readiness, some chargers apply a brief topping charge to compensate for the small self-discharge the battery and its protective circuit consume. This reduces voltage-related stress and prolongs battery life.


Fast Charging Standards:

Standard.. Hmm! There is no such standard for fast Charging. Different manufacturers develop various charging standards that are capable of varying outputs and charge times. However, it depends on three devices. You need the right equipment to get it through.

  1. Charger

  2. Cable

  3. Phone

Once you have a charger and cable with the fast charging standard compatible with your phone, the process will start. For example, if you are using a 18W charger with a smartphone that has a maximum charging speed of 12W, the phone will charge at 12W.


Below are few standards which is being used by different manufacturers depends on the processor or platform they used.


Qualcomm Quick Charge:

Quick Charge (QC) is a Fast Charging protocol developed by Qualcomm, used for managing power delivered over USB (different types). The onboard device mainly communicates to the power supply and negotiates voltage and current. This Quick Charge technology is supported by devices which run on Qualcomm SoCs (Systems On Chip / Processor), and by some chargers as well. Starting from QC 1.0 to the latest QC 5.0 is a massive development in this Li-Ion battery charging technology for mobile phones.

Quick Charge 5 is world’s Fastest Commercial Charging Solution delivering astonishing charging speeds of up to 0-50% in five minutes while enabling new battery technology, accessories, and safety features.

See more about Quick Charge 5

Samsung Adaptive Fast Charging:

Adaptive Fast Charging (AFC) is the smartest option to charge your Samsung mobile devices. Not only is it speedy, but it knows when to stop charging to prolong the longevity of your mobile phone battery. This AFC technology rapidly recharges your compatible device's battery from 0 to 50% in about 30 minutes, so you can spend less time connected to an outlet and more time connecting with people you care about.


The Adaptive Fast Charging wall charger will charge other Micro USB devices without the Adaptive Fast Charging feature as well, with just a standard 2 Amp charging rate.


OnePlus Dash and Warp Charging:

OnePlus uses the proprietary Warp Charging standard for their devices, which charges their devices up to 65W. Built-in, dedicated charging circuitry ensures efficient heat management and dissipation to keep your phone cool while charging. Reliable and always fast, charging is safer too thanks to automatic hardware safeguards and software optimizations. The OnePlus 8T took 15 minutes to charge from 1% to 58% and for full charging it took only 39 minutes.

Previous generation of Warp Charge is basically Dash Charging which uses a 5V / 4A (20W) configuration.


The OnePlus Warp Charge 65 Power Adapter supports Warp Charge 65, Warp Charge 30 and Fast Charge technology of its own devices. The power output depends on the device the charger is connected to.


Oppo Super VOOC Charging:

Oppo VOOC (Voltage Open Loop Multi-step Constant-Current Charging) is a proprietary rapid-charge technology created by BBK Electronics. The Super VOOC Charge technology reportedly lowers the temperature of the charging adapter, and creates an interface from the adapter to the phone, which, OPPO claims, improves the speed and safety of the charge. OPPO Super VOOC Charger supports Super VOOC 2.0 technology, the maximum output power is 65W, allowing users to recharge at the fastest speeds longer. It can charge your OPPO Reno Ace in 30 minutes from zero to 100%.


MediaTek Pump Express:

MediaTek Pump Express 4.0 cuts smartphone battery recharge times by over half, compared to a standard USB charger. It supports the latest USB-C cable standard, with up to 5 Amps of current. This technology is compatible with the international standard of USB PD 3.0 programmable power supplies, allowing standard USB PD 3.0 fast chargers to boost Pump Express 4.0-enabled smartphones.


USB Charging:

Every mobile phone has a charging cable that uses USB (other side is lightning cable). USB 2.0, which has been a common specification for two decades, has a maximum power output of 2.5W. Because there’s a requirement for USB ports to deliver more power, the USB-PD standard was created. USB-PD has a maximum output of 100W and is used for a wide array of devices, including most flagship mobile phones. All USB 4 devices will include USB-PD technology, which will hopefully help standardize this.


Apple Fast Charging:

Apple uses the USB-PD for the Fast Charging method. The Lightning cables for Apple’s iPhones have a USB connection on the other end. Apple uses an 18W charger for the iPhones which claims that 50 percent charge in battery in just 30 minutes.


Motorola Rapid Charging and TurboPower:

Motorola TurboPower introduced a 45W Wall Charger with 5 Amp E-marked USB-C Cable which is named Hyper Charger. Although this charger uses USB-PD 2.0 (power delivery) with PPS (Programmable Power Supply) for fast charging. Motorola Hyper charger supports peak charging speeds for the Motorola One Hyper. It is broadly compatible with QC4+ and Power Delivery technology. Its compact size makes it an ideal travel companion to power up your USB-C phone that uses USB-C as their charging port. Users can get up to 12 hours of power in just 10 minutes of charging for the Motorola One Hyper Charger.

The output specification of this charger is,

  • 5V 4A (default)

  • 9V 4A

  • 15V 3A

  • 20V 2.25A


What is the Future of Fast Charging?

Battery charging technology is continuously getting improved and more efficient. Different manufacturers invest their time and money to introduce new technologies so that this process can be more efficient. However, it’s likely that most of these standards will still use USB-PD as their backbone. However, the future is wireless charging. Either directly the phone or Air charging. There’s also the emergence of wireless fast charging. Recently, Oppo introduced a wireless charging of 65W which is a bit higher than the few wire based chargers. However, wireless charging is still significantly slower than wired charging because of technology. Oppo has 125W wire charging technology. I'll cover separate topics to cover those.




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