Brief educational programme about fast and wireless charging technologies

FAST CHARGING

Fast charging technology allows you to significantly save time spent on replenishing the energy reserves of portable gadgets. Another important advantage of its use is the partial charging of the battery in a matter of minutes, which is enough for several hours of subsequent operation of the mobile device. The relevance of using this technology is steadily growing due to the increased energy consumption of portable gadgets (primarily smartphones) and the increasing capacity of batteries, which requires more time to charge them.

How it works

Graph of the dependence of the charging current power on the battery charge in Qualcomm Quick Charge technology.

The principle of operation of fast charging is considered on the example of Qualcomm Quick Charge technology — the discoverer and trendsetter in the field of rapid replenishment of energy reserves in mobile gadgets.

At the first stage, the charger provides the output of the maximum possible power of the charging current, gradually reducing its values closer to the end of the charging process (in order to ensure the integrity of the battery cells).

The power parameters are calculated based on the values of the output voltage and current strength. They may differ depending on the generation of the technology.

Three generations of Quick Charge

Qualcomm's technology, announced to the general public in 2012 — Quick Charge 1.0, became the first-born among fast chargers. It assumed savings of about 40 % of the time when filling the battery tanks due to the use of increased amperage at the standard value of the output voltage: 5 V and 2 A versus 5 V and 1 A in normal mode.

The second generation of Quick Charge 2.0 has learned to work with voltages of 5 V, 9 V, 12 V, 20 V and a current of up to 3 A, which made it possible to speed up the charging time by 75%.

The most advanced is the third reincarnation of Quick Charge 3.0 technology. She learned to intelligently select the optimal charge voltage in the range from 3.6 V to 20 V in increments of 200 millivolts. In comparison with the second version, the efficiency of fast charging has increased by another 38%. Quick Charge 3.0 is supported at the hardware level by top Qualcomm Snapdragon processors 820, 620, 618, 617, 430.

The picture below clearly demonstrates the difference in charging speed when using different generations of Qualcomm Quick Charge technology. At the same time, the battery with a capacity of 2750 mAh will be charged either by half (3rd generation), or slightly less (2nd generation), or even by only 13% (in normal mode).

The difference in charging speed when using different generations of Qualcomm Quick Charge technology.

In addition to the support of the technology by the chip of the corresponding mobile gadget (smartphone, tablet, external battery, etc.), the successful operation of fast charging is guaranteed if a compatible charger is used. By the way, if you connect such a charge to a device without Quick Charge support, nothing bad will happen to it, because the gadget controller will provide charging at its usual pace. In simple words, it will take only the power of the charging current that it needs.

According to various studies and tests, the fast charging technology does not have a negative impact on the battery performance and its service life. Both scientists and battery manufacturers agree with this.

Alternatives

The manufacturer of processors for smartphones MediaTek has created its own Pump Express fast charging technology.

Other manufacturers are trying to keep up with Qualcomm. For example, its closest competitor in the production of processors for smartphones MediaTek called its own fast charging technology Pump Express. Its first generation is able to charge gadgets with a voltage of 3.6-5 V and a current of 2 A. The second generation is more advanced — it is characterized by working with voltages of 5-7 V, 9 V and 12 V at a current strength of up to 3 A.

Samsung's Fast Charge Fast Charge operates with voltage values of 5 V and 9 V, as well as currents of 2 A and 1.67 A, respectively.

The Asus Boost Master technology is found on Asus ZenFone 2 smartphones. The total power of the charging current when using it reaches 18 watts (voltage 9 V and current 2 A).

But the VOOC Flash Charging fast charging, first used in the OPPO Find 7 smartphone, stands out among its peers — it charges the 3000 mAh battery by half in less than 20 minutes. The merit of this lies on the shoulders of the battery itself with an increased number of contacts and a high charging current (4.5 A at a voltage of 5 V).

Unfortunately, solutions from different manufacturers are incompatible with each other, because there is no generally accepted standardization of the functioning of fast charging technology. What can not be said about the next point of the story — wireless charging of gadgets.

WIRELESS CHARGING

Data transmission over wireless networks, music streaming via wireless headphones, and now wireless charging — everything is aimed at eradicating annoying wires as a class.

How is electricity transmitted through the air?

The principle of operation of wireless charging.

The principle of operation of wireless charging is based on the phenomenon of electromagnetic induction. Special induction coils are used in the charger and mobile gadget, the role of which is most often played by a smartphone or a "smart" watch. They are different: a transmitter coil (transmitter) is installed in the charging, and a receiver (receiver) is installed in the body of a compatible device. Electromagnetic field fluctuations are formed around the wireless electricity transmitter, which are converted into electric current on the receiving side.

The requirements for wireless charging are clearly spelled out in the Qi standard developed by the WPC Wireless Electromagnetic Energy Consortium. In particular, the standard describes the operating characteristics (excitation current frequency 100-205 kHz, rated power 5 W) and regulates the distance between both coils (should not exceed 5 cm).

Note that the efficiency of wireless charging systems is several times lower than that of the usual wired method. In the latter case, it reaches 97%, whereas when using the effect of electromagnetic induction, at best it will be possible to get a value at the level of 80%. Accordingly, the charging speed when using wireless technology does not differ for the better.

The areas of application of wireless charging most widely cover smartphones, smartwatches, electric shavers and toothbrushes.

Advantages and disadvantages

Wireless charging is convenient because it allows you to get rid of wires.

The main advantage of wireless charging is the ability to get rid of wires, as well as practicality — already the number of points for wireless charging of gadgets is actively growing in many airports and shopping malls. This allows you to completely forget about the need to carry a charger or an external battery.

The main disadvantage, as mentioned above, is manifested in a slower rate of replenishment of the energy reserves of the battery due to the lower efficiency of wireless electricity transmission systems. Another disadvantage is the cost of wireless chargers, which is several times higher compared to wired ones.

Finally, it is necessary to clarify the point regarding the impact of such a method of charging on the human body. Since electromagnetic waves are included in the spectrum of non-ionizing radiation, they do not have a negative impact on health. Such radiation is used to relay a mobile signal, data transmission (Wi-Fi or Bluetooth) and in other everyday cases. The impact on other home wireless networks is also excluded due to the different frequencies of the wireless systems.