The battery capacity of modern smartphones is constantly growing, but energy consumption is also increasing. An increase in battery capacity has a positive effect on autonomy, but leads to an increase in charging time. If a device like the first iPhone or HTC HD2 could be charged from a USB 2.0 port in 2 hours, now some Lenovo Vibe P2 will require about 10 hours. To reduce the time spent on charging, manufacturers are actively introducing support for the fast charging function.
Fast charging in a smartphone is a technology that works on the principle of increasing the current strength that is supplied to the battery from the power supply. Initially, power supplies for charging mobile devices produced a voltage of 5 V with a power of 500-1000 mA. But with such parameters, theoretically, an hour can be replenished for more than 1000 mAh smartphone battery capacity. In practice, this value is even less, since the more the battery is charged, the more it is necessary to reduce the current strength.
The principle of operation of fast charging in a smartphone
The very first way to speed up the charging process is to increase the amperage. Early technologies made it possible to produce a current of up to 2 amperes at a voltage of 5 volts, which gave a power of 10 watts. However, it turned out to be difficult to move this way further: thick currents require thick wires, since the resistance of the cores depends on this. With a low-quality cable, even 2 A is not easy to get, as there will be drawdowns.
It is problematic to use a cable with a large cross section, so the manufacturers decided to go by increasing the voltage, while maintaining the same current strength. However, lithium batteries require a narrow range of voltage to charge, it is impossible to apply “clean” 12 V to the contacts. To solve the problem, special charge controllers have been developed that are built into the chipset or on the motherboard. They accept voltages above 5 volts, converting it to optimal for battery cells.
Types of fast charging for smartphones
In order to increase the charging speed, smartphone component manufacturers are developing new fast charging technologies. Qualcomm offers QuickCharge, MediaTek has a competing PumpExpress, and OPPO has an analogue called VOOC. Samsung offers users Fast Adaptive Charging. Asus smartphones have Asus BootMaster support, Motorola TurboPower, and Huawei. SmartPower
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Current generations of QuickCharge and PumpExpress are able to use different voltages, power supplies can give from 5 to 12 V. The charger interacts with the charge controller, from which it receives “hints” about what current and voltage should be given out at the moment. It can be used as step regulation (5, 9, 12 V, etc.), and smooth (from 3.2 to 20 V, with a step of 200 mV, used in QuickCharge 3.0).
Since the chipset is responsible for wireless charging, the type of technology used depends on it. The methods of Qualcomm, Samsung, Mediatek, Huawei, that is, companies that produce chipsets, can be considered independent. Oppo’s VOOC stands out. It is implemented through the use of multi-cell batteries that can be charged in parallel. Due to this, “fill” 2500 mAh in just 15 minutes.
Other fast charging technologies are usually QuickCharge-based variations called by a different name. But in general, they all use one principle: first, the power supply gradually increases the current and voltage, choosing the maximum possible parameters, then at maximum power charging occurs to 50-70% of the capacity, and then there is a smooth decrease in current and voltage.
Is wireless charging harmful in smartphones?
Lithium (lithium-ion and lithium-polymer) smartphones are sensitive to charge. The use of poor-quality memory, charging and discharging with excessively large currents can reduce their life, so there are allegations of the dangers of fast charging.
In fact, the power controller is a rather complicated device that is able to select the optimal mode of replenishment of capacity. While the charge density in the battery cell is low, it selects the maximum possible charging power. With an increase in density, chemical processes in the battery are accelerated, heating intensifies (and it damages it). The controller detects this and reduces the power supply to prevent heating. As a result, the temperature regime is maintained normal, the negative impact on the battery is minimized.
Can a smartphone explode due to fast charging?
News on smartphone explosions often pops up on the Internet, and horror stories about the fact that this is due to fast charging are very common. In theory, this is really possible, but often the problem is not in fast charging technology, but in faulty equipment. The use of low-quality power supplies and cables, the use of smartphones with a damaged battery, a deformed case, etc. these are the main causes of explosions and fires.
To avoid a fire, explosion, or simply bloating of the battery, it’s enough to follow a few simple rules. You can’t cover the infected smartphone with a pillow or other object, leave it to be charged on the windowsill or panel of the car heated by the summer sun. It is also not recommended to use cables and power supplies of dubious origin.