Once upon a time, phones had weak batteries, so they charged quite quickly. Since then, their capacity has increased by about 5-10 times, and their charging time should have increased by the same amount. Manufacturers are solving this problem different ways, but their capabilities are limited, because they try to adhere to established standards.
Most smartphones are charged from chargers that produce a voltage of 5 volts with a current ranging from 0.5 to 2 amperes. However, there are accelerated charging technologies that provide increased voltage and current. The operating principle of any battery is based on an electrochemical process that allows you to accumulate energy and then release it. In modern mobile devices ah, lithium-ion and lithium-polymer batteries are most often used, which have high capacity and low self-discharge. They have many disadvantages - over time they gradually lose their nominal capacity, and when heated and damaged they can ignite.
At the heart of technology fast charging lies the principle of supplying the maximum permissible voltage at a current strength that allows you to collect a charge as quickly as possible. At the same time, it is important that the battery is not damaged, does not fail, and does not lose its characteristics. The voltage is selected individually for each device and charging conditions and can be increased or decreased. In the case of Qualcomm Qiack Charge technology, charging is carried out at voltages from 3.6 to 20 volts in 0.2 volt increments and current up to 3 amperes. The controller built into the processor analyzes several parameters, including battery temperature, and allows you to limit or increase the energy supply. Devices are charged in a similar way using most other technologies.
Oppo has invented its proprietary VOOC Flash Charging technology, which works differently. The charger supplies a current of 5 volts with a power of 4.5 amps to an 8-pin battery. The battery is divided into several cells, and the energy is evenly distributed between them. This technology allows you to “carefully” charge batteries without exposing them to the risk of overheating even in the event of a controller failure or failure.
There are also more radical solutions - for example, charging the battery in a few seconds. This technology is far from perfect - the battery discharges several times faster and it is very short-lived.
Chargers that support fast charging technologies are universal - they can charge smartphones from any manufacturer, including older models. It is unlikely that we should expect a sharp breakthrough in accelerated charging technologies. Most likely, they will gradually improve, and within a few years the generally accepted norm will be to fully charge a smartphone within half an hour or even faster.
There are two categories of users. For some, the fast charging function is a given, that is, something that is present in their smartphone by default and does not pose any threat. The latter regard fast battery charging with some concern. They have heard or read that the technology accelerates battery wear and sometimes even leads to irreparable consequences, such as battery explosion.
In this article we will talk about how the fast charging function works, whether it can pose a threat to a smartphone, and if so, how to avoid trouble. By the way, we recommend that representatives of both categories read the material, since with this technology not everything is as simple as it might seem at first glance.
A little physics
(If you know physics well, you can skip this short section.) Let's start not with the power or voltage of the fast charger, but with the fact that in the process of recharging the phone, you fill the battery with energy. The maximum energy reserve of a battery is determined by its rated capacity. The speed of energy replenishment depends on the parameters of the current through which energy is transferred from the adapter to the phone.
The universal measure of electrical energy is power, which is measured in watts. The higher the current power, the more energy it carries. In turn, the power of the electric current depends on its strength and voltage. Current is measured in amperes, voltage in volts. Perhaps such a beginning will seem primitive to some, but do not forget that not everyone remembers the physics that was taught back in high school. And there is nothing wrong with that.
Fast charging function: working principle
The first smartphone chargers produced 5 watts of power at 5 volts and 1 amp (5 watts = 5 volts x 1 amp). Such a charger can replenish approximately 1000 mAh of battery in 1 hour. It turns out that a 4000 mAh battery will charge in about four hours. Either way, it's too long. Fortunately, such adapters are rare today; a 10-watt (5 volt, 2 ampere) device is considered standard.
The fast charging function speeds up battery replenishment by increasing the power of the electric current. To increase power, it is enough to increase either the voltage (make it more than 5 volts, in practice - up to 9-12 volts), or the current (more than 2 amperes, in practice - up to 4-5 amperes), or both parameters at once. As a result, at the output of the adapter we get a current with a power of 15 watts to 50 watts, with which the rate of energy replenishment increases by 5-10 times.
Fast battery charging: what is a controller?
So far everything is simple - you increase the current or voltage, and instead of three hours you charge for 40 minutes. Is that how it works? Not really. Quickly charging a phone battery poses many challenges. Although these problems are successfully solved by manufacturers at the gadget development stage, it is necessary to know about them, otherwise you may accidentally ruin an expensive toy.
The first problem is that the battery cannot be supplied with a voltage greater than 5 volts. How is it, you ask, that my charger says the voltage is 9 volts? Yes, the output voltage from the adapter is 9 volts, but a lower voltage current is supplied to the battery. Redistribution occurs already in the phone with the participation of the controller, without which fast charging of the battery would be impossible.
The controller is a microcircuit in which the circuits and power circuits for recharging the battery are defined. Typically, the controller is integrated into the chip. Each processor family has its own controller type, which determines the type of fast charging supported by the device. For example, smartphones powered by Snapdragon processors support Quick Charge fast charging, phones powered by MediaTek chips support Pump Express, and Samsung smartphones on Exynos chips - Adaptive Fast Charging. 
Quick Charge 3.0 is backwards compatible with Quick Charge 1.0 or QC4.0, but there is no cross-compatibility between different controllers. You cannot charge a Snapdragon phone with the fast charger that came with the MediaTek phone. In the best case, it simply will not charge quickly (or will not charge at all); in the worst case, the gadget may fail.
Fast charging cable: why is it important?
The connecting link between the controller and the adapter is a fast charging cable. Manufacturers usually include the required USB cable in the box with the phone. With any other cable, the smartphone charges slowly, that is, the fast charging function does not work. Why is that?
Here we come to the second problem - energy loss and current strength. If the current is greater than 2 amps (which is typical for fast charging), a good cable with a large cross-section is needed to efficiently transfer energy with minimal losses. Otherwise, the losses will be too large, causing fast charging to turn into regular charging. In practice, manufacturers often use protection - when an unsuitable cable is connected, the adapter produces standard current characteristics (5 volts and 1 or 2 amperes).
The fast charging cable performs another important function - it is the link between the controller (microcircuit in the smartphone) and the charger that you plug into the network. Via the cable, the controller transmits information about the charge density of the battery, which is necessary to prevent overheating. When the density increases (the battery is 75-80% charged or more), the charger reduces the current power and the phone begins to charge more slowly.
Fast charger and its role
As you can see, the fast charger is not an ordinary plug, but a complex adapter that dynamically changes current parameters (current strength and voltage) depending on the percentage of battery charge. If the battery is completely discharged, the fast charge charger delivers maximum voltage and current. If the battery is almost full, the power is reduced to avoid overheating, and this happens at the outlet of the adapter.
So, the fast charging function is implemented using a three-component system. The system consists of a controller on a chip, the correct USB cable and an adapter that dynamically changes the current and voltage depending on the percentage of battery charge.
All system components must be compatible with each other. The charger must support the fast charging standard provided by the smartphone processor: Quick Charge in phones with Snapdragon processors, Pump Express in a smartphone with a MediaTek processor, or Super Charge in Huawei and Honor smartphones with Kirin chips. 
Without such compatibility, the phone will either not charge quickly or will not charge at all. If a faulty, low-quality or uncertified cable or adapter is used, irreparable consequences may occur.
Can it be charged with fast charging?
In fact, this question worries many users, which once again proves the need for a detailed and thorough analysis of the operating principle of this technology. If you've read the previous sections carefully, the answer should be obvious.
The phone can be charged with fast charging, provided you use the charger and cable that come in the box.
The included cable and adapter are certified and exactly compatible with the fast charging standard supported by your smartphone. But what if the original cable (or adapter) fails or is simply lost? In this case, you must purchase a certified cable or a certified charger that supports the standard you need. Alternatively, you can use a regular 10-watt charger. In this case, you can forget about fast charging, but at least the phone is not in danger. 
1. Never charge your phone with a damaged cable. Modern flagships have a built-in cable check, but inexpensive phones don't, so this task falls on your shoulders. If there is mechanical damage, or if you see that the phone is charging somehow “wrong”, contact service center.
2. Never use a faulty charger. In the best case, a faulty adapter cannot dynamically change the current and voltage; in the worst case, it does not control them at all. When purchasing a new adapter, pay attention to the current and voltage - they should be the same as on your original charger.
3. Take your damaged smartphone (mechanical damage, drowning) to the service center. If the power circuits, contacts on the battery or other components are damaged, even a smartphone that is working properly after drowning may unexpectedly “burn out.”
4. Don't charge your smartphone in the sun. In practice, this means that while charging, you should not place the phone on the car dashboard or on the windowsill if it is exposed to direct sunlight.
5. Don't cover your phone while charging. A simple example: while charging, the phone is lying on the sofa, and you accidentally covered it with a pillow. A seemingly harmless mistake can result in overheating and failure.
And the last piece of advice regarding fast charging itself. If your gadget supports this technology, use only the included accessories (cable, charger), and if they are broken or lost, purchase certified products from official sellers. And you don’t need to charge Samsung with an adapter from Huawei or vice versa.
Over 5 years, productivity in mobile electronics has increased 5-10 times, while battery production technologies have remained unchanged. The average battery capacity is 3000 mAh, which is 3 – 3.5 times higher than that of phones of the last decade. At the same time, there is a tendency for capacity to decrease due to a decrease in the thickness of the case, which will negatively affect the battery life of the mobile device.
As a temporary solution, fast charging technology has been developed that can speed up the charge replenishment process by up to 75%. As a result, waiting time is reduced and mobility is increased, since the user is not chained to a power outlet for 3-4 hours. Let's take a closer look at the technology, operating principle, advantages and disadvantages.
What is fast charging
Fast charging is a technology that aims to increase the capacity of voltage (V) or current (A), or both. The point is to recharge the built-in power source as quickly, efficiently and safely as possible. The charging speed is affected by current parameters, as well as the generation of fast charging.
Use cases
The essence of fast charging technology is to quickly charge the battery. Therefore, this option will be useful for users whose devices are equipped with small-capacity batteries or, due to being busy, actively consume power. Let's consider the effectiveness of using technology in real life.
Charging a high-capacity battery
Some smartphones and tablets are equipped with power supplies of 5000 – 12,000 mAh. Charging such devices network adapter with current parameters 5V/1A it will take 6-14 hours. And with the use of first generation fast charging (5V/2A), the waiting time will be reduced by almost half.
Recharging for an emergency
Suppose that on the way to work or school, the game drained the smartphone, and for the rest of the day the charge will only be enough for telephone conversations. You need to replenish the charge, and you have 15 minutes of free time. During this time, the 3000 mAh battery will charge:
- Standard charger 5V/1A – 8.3%.
- Fast charging 1st generation 5V/2A – 16.7%.
- Fast charging 2nd generation 9V/2A – 30%.
Operating principle
The charging process consists of two stages. At the first stage, the current power is as high as a smartphone or tablet can receive. The second stage begins when the level of 60-75% is reached. The current strength begins to gradually decrease, and the charging process at this stage extends for 30-60 minutes. This is done to ensure that the battery does not overheat and fail.
Fast charging technology uses the same principle of operation, with the only difference being that in the first stage the current or voltage, or both, is higher. So at the beginning of the process the battery is charged quickly, and at the end at normal speed. And it is advisable to use the technology when the battery is discharged to 15-30%. Therefore, marketers write that the battery will be charged 60 or 75% in 30 minutes, but do not specify the time for full charging - 1.5-2 hours.
It is worth noting that fast charging technology is incorporated during the development of a mobile device. It requires installation of an appropriate processor, as well as a power controller capable of receiving and distributing energy from high values current/voltage. And most importantly, you need a network adapter that supports the necessary parameters.
Which Android smartphones and tablets support fast charging technology
The manufacturer indicates support for this technology on the box or in the package list. For example, on the box of the Motorola Droid Turbo 2, a proprietary charger with a power of 25 W is indicated. Information about technology support is also indicated in the specifications on the company’s website.
It is important to know that some manufacturers do not provide chargers that support fast charging technology. In this case, the user is forced to buy a network adapter separately.
How to choose a charger that supports fast charging
On the manufacturer's website you need to specify the type of fast charging, as well as the parameters of the received current: 2A/5V, 2A/7V or 2A/9V. Then select the appropriate charger, which will indicate fast charging support and the required current / voltage ratio.
Types of fast charging
Qualcomm Quick charge.
Qualcomm is the founder of fast charging and the leader of this technology, due to the widest distribution of chips and processors for mobile electronics. In four years, three generations of fast charging have appeared.
Quick charge 1.0
Increasing the current to 2A, adapter parameters 2A/5V, power 10 W. Compared to conventional 1A/5V AC adapters, the charging process is almost 2 times faster (2000 mAh per hour).
Quick charge 2.0
The voltage increased to 12V, adapter parameters 2A/5V, 2A/7V, 2A/9V and 1.2A/12V, power up to 18 W. Compared to the first generation, the charging process will be reduced by 1.8 times (up to 3600 mAh per hour). In this case, the user can be given a choice of charging speed by manually switching the voltage from the device menu, or the voltage is fixed - 7V or 9V. In both cases, the decision is made by the mobile device manufacturer at the development stage.
Quick charge 3.0
Improving the charging process by dynamically changing the voltage (3.2 - 20V in steps of 200 mV). The network adapter parameters and power are the same, but Qualcomm notes an increase of 3-8% or more.
MediaTek Pump Express
Competing fast charging solution for MediaTek processors. Due to the low penetration of the technology, details are scarce, but the principle of operation is the same - increasing the current, voltage, or both. Also, the Chinese manufacturer does not hesitate to talk about its superiority over its competitors without citing specific numbers.
Pump Express
The first generation of fast charging with voltage 3.6 - 5V, current 1.2 - 2A, power 5 W (1.2A), 7.5 W (1.5 A) and 10 W (2A).
Pump Express Plus
Second generation with increased voltage (5, 7, 9, 12) and current up to 2A: 15 W (9V/1.67A) and 24 W (12V/2A).
Pump Express 3.0
Nothing is known about the third generation of fast charging. According to MediaTek, 70% of the charge will be replenished in 20 minutes.
In addition, fast charging technology is being developed by mobile electronics manufacturers: Motorola - TurboCharge, Samsung - FastCharge, ASUS - BoostMaster, etc. The essence is the same, charging the smartphone with a 15 or 18 W power adapter (2A/9V, 1.67A/9V or 3A/5V).
The distinctive implementation of OPPO (VOOC Flash Charging) and its subsidiary OnePlus (Dash Charge) is 4A/5V (20 W). In this case, the battery is divided into several cells, through which the current is evenly distributed.
Advantages and disadvantages
The advantage of the technology is the fast and safe charging of a mobile device. This reduces waiting time and increases mobility. In addition, claims that the use of fast charging accelerates wear and tear of the battery have been refuted by scientists from Stanford University and the Stanford Institute for Materials Science and Energy. At the same time, scientists were able to understand the structure and internal processes in order to increase the charging speed in the future without consequences.
At the same time, the main disadvantage of the technology is the slowdown in the search for new power sources, as well as the optimization of energy consumption. For companies, it is better to recharge the battery 2-3 times a day than to achieve slow energy consumption.
Conclusion
Fast charging technology – effective method replenish battery energy and increase mobility. There are interesting developments in this direction, including UMB with the Quick charge function. But due to the common myth about accelerated battery degradation, users prefer to continue to use adapters with low current supply. Therefore, companies should invest in optimizing energy consumption and increasing capacity while maintaining battery size. Sometimes scientists announce new power sources for portable electronics. But until companies and corporations see profit in this, the situation will remain unchanged.
Smartphones, unlike the first mobile devices, we are already accustomed to charging almost every day due to their high energy consumption. Reducing battery charging time has become a pressing issue. While small, capacious batteries are only in the development stage, smartphone manufacturers are focusing on introducing fast charging technologies.
How is fast charging different from regular charging?
First of all, the current power: Fast Charge produces a voltage of up to 20 V and a current of up to 5 A versus 5 V and 2.5 A in traditional chargers. In addition, fast chargers can adapt to the smartphone and dynamically adjust power depending on the state of the battery.
Previously, the charging process followed a simple algorithm: up to 90% of the battery was charged with a current of the same power, and at the end of the cycle the parameters were reduced to avoid heating and “overcharging” the battery. New technologies vary the current power over a much wider range: for example, Qualcomm's Quick Charge 3.0 can produce a voltage of 20 V at the very beginning of the charging cycle, gradually lowering it to 3.2 V in 200 mV steps. The optimal voltage is selected for each smartphone, taking into account the battery charge level. As a result, the technology significantly reduces charging time without damaging the battery.
There is no single Fast Charge standard yet; each manufacturer supports its own, and there is no compatibility between them. The most common technology is from Qualcomm, which is implemented in most smartphones. The company is preparing to release the fourth version of Quick Charge. This fast and smart charger will support the USB Power Delivery standard created by Google for all Android devices, from smartphones to laptops. Perhaps other manufacturers will follow Qualcomm's example, USB PD will become a platform for combining different standards, and we will gradually come to the point where one charger will be suitable for different gadgets.
How to properly charge your smartphone.
The modern fast charging system includes:
- controller, which is often built into the smartphone processor
- charger that produces a current of certain values
- high power cable
This leads to the conclusion that to quickly charge a smartphone, it is best to use the included power supply, since in this case all parts will correspond to each other. However, connecting a third-party charger to your smartphone will not harm the battery. In the worst case, the device will charge at the standard speed, as when using regular chargers.
If you use fast charging for a “someone else’s” smartphone that does not support it, nothing bad will happen either. Fast charging will work in basic mode and produce standard 5 V and 1-2 A, which are suitable for any device.
Remember simple rules security:
Don't overload RAM, do not talk on the phone while charging to avoid overheating the battery;
Do not cover the charging smartphone with anything (make sure it is not under a pillow or blanket);
Do not charge a device if the case, battery, or cable is damaged (scratches, cracks, or bent).
Is fast charging dangerous for the battery?
There is a widespread belief that charging with increased current can negatively affect the battery's performance and even lead to a fire. Let's address these concerns.
Smartphones use lithium batteries, which are characterized by the following properties:
Lithium does not have a “memory effect”. Thanks to this, the battery can be charged without waiting for complete discharge, and not to full 100%. If not for this advantage, fast charging would not be so popular.
Over time, the capacity of lithium batteries may decrease, since the battery itself is designed for approximately 2000-3000 charging cycles. Indeed, when the first versions of Fast Charge appeared, battery aging could accelerate if charging was done too often. Now fast charging standards affect battery wear to such a small extent that they are included in the statistical error when determining the average life of the battery.
For a modern battery, it almost doesn’t matter what current it will be charged with. Let's give an example: laptops are equipped with the same lithium-ion batteries as smartphones, only larger. Their charger produces a current of 4-5A and 20V, and no one is afraid that this will damage the battery. Fast charging produces high-power current only for the first 15-20 minutes, and in comparison with charging similar batteries in laptops, this current is still less.
The real danger for lithium batteries is overheating, as it reduces the battery's capacity and can lead to fire and explosion. Fast charging technologies have several degrees of protection against overheating, so they are even safer than traditional ones.
Thus, Fast Charge does not harm the smartphone battery. In addition, these technologies are implemented in modern gadgets at the firmware level and it is impossible to “disable” the fast charging function. And it’s not necessary, since new charging standards make smartphones more advanced and make life easier for users.
(Quick Charge), so users actively use this useful technology. QC allows you to quickly and efficiently charge your smartphone; in just an hour, the battery charge is 100% again. For our readers, we have prepared material that will help you learn everything about Quick Charge 3.0 and how it works.
Quick Charge
Qualcomm Technologies continues to introduce new innovations to the mobile device market. At one time, Quick Charge 1.0 technology clearly demonstrated that smartphones can charge 40% faster than with conventional charging.
A year later, QC 2.0 was introduced, allowing the device to be charged 75% faster. In addition, various accessories compatible with this technology were presented.
In 2015, Qualcomm Technologies continues to develop its industry. Quick Charge 3.0 charges even faster and more efficiently. By the end of 2017, Xiaomi has already released more than 10 smartphone models that support QC 3.0
With Quick Charge technology, more than high level current, thus charging becomes as fast as possible.
For successful charging, the device and the charger itself must be compatible with the same voltage and current.
For example, if the phone supports a 9V/2A charger, but it charges with a 1A charger, the process will take much longer.
Another example, if a charger with a specified current of 2A is used to charge a smartphone that supports a maximum of 0.7A, this will not make it charge faster.
The phone can also be charged faster if a similar charger is used, but with a higher current.
Note: products without a certificate are not guaranteed declared effectiveness.
How does Quick Charge technology work?
Quick Charge technology allows you to optimize the energy supply to your smartphone battery during the first stages of charging.
Thus, some phones can be charged up to 80% in just half an hour. However, in the final stages of charging, the energy transfer is not as high, regardless of which charging technology is used.
Consequently, the battery can be charged up to 50% in a short amount of time, but you will still have to wait more than an hour to fully charge the smartphone.
QC 3.0 charges mobile devices 4 times faster. Compared to QC 2, charging speed has increased by almost forty percent.
Qualcomm focuses consumers' attention not on increased charging speeds, but on increased efficiency. Thus, the main innovation in the technology is the INOV function, which is capable of intelligently selecting the required voltage, more accurately optimizing the power and charging time of a particular device.
Differences between QC 3.0 and previous versions
To understand the main differences latest version quick charge technologies from previous ones, just look at the table below:
After reviewing, we can conclude that due to the increased voltage, the charging time of devices decreased from version to version. The maximum power in the third version remained almost the same as in the second - 18 W. At the same time, low voltage batteries receive higher power. Thanks to this, they charge much faster.
Why doesn't my phone support fast charging? This is exactly the question most often asked by owners of smartphones that do not support Quick Charge. For example, owners of a new smartphone running stock Android would be very disappointed by the lack of Quick Charge in the device.
The problem is that Qualcomm's technology is proprietary. And its support depends on the model of the installed processor. These are the nuances that developers take into account when releasing a new smartphone.
According to the instructions from the Qualcomm website, they do not prohibit the use of certified adapters on phones without fast charging. Yes, your smartphone will charge properly, but you won't be able to experience all the benefits of Quick Charge when charging your device.
Conclusion
The Quick Change function is quite promising and in demand. The developers are not sitting idly by, but are improving it, complementing the 4th generation of fast charging technology with new functions.
Users will be pleasantly surprised by the new Xiaomi smartphones supporting Quick Change 4.0, the presentation of which is expected in the first quarter of 2018.