In recent years, one important concept – fast charging – has slowly made its way to the fore. Who doesn’t want a smartphone that can charge in minutes instead of hours?
Actually, Apple, Qualcomm, Samsung, MTK, Huawei, OPPO and other brands have their own fast charging technology.
Currently, there are two main implementations of fast charge technology.
High-voltage fast charge: Qualcomm QC2.0, QC3.0 have adopted high-voltage fast charge, its principle like this: the adapter output is 9V, current 2 amps, transfer to the phone needs to be converted into battery voltage (such as 4.0V), enter the current to the battery may also be only 4 amps. The power received by the battery at this time is the same as 4.0*4=16 watts, but the power output from the adapter is 9 volts*2 amps=18 watts. In addition 18-16=2 watts of power are all turned into heat in the process of high voltage converse to low voltage, which will cause the fuselage getting hot. Normally we call 16/18 as level conversion efficiency. Under the same conditions, the higher charging voltage, the lower the conversion efficiency will get and the higher the heat will be.
Low-voltage fast charge: Dash flash charge adopts low-voltage fast charge. When the adapter transfers current through the USB cable to the mobile phone, the voltage of the output terminal is basically consistent with the mobile phone internal battery voltage. For example, the battery voltage is 4.0V, and the voltage at the adapter end is about 4.0V. So without going through any conversion circuit, 4 amps of current can be injected into the battery without any loss. The total charging power is 4.0*4=16 watts (of course, the safety protection circuit is the most basic thing here). Because there is no voltage conversion process, only a small amount of power is converted into heat during the charging process (current flowing through the conductor will have I2*R heating). This is the principle that Dash Flash Charger can fast charge when you play the cell phone, of course, if When playing some large-scale games in a high temperature environment, the heat of the mobile phone rises, and the charging current will be slow down for the battery safety.
The vitality of high-Voltage fast charge has basically come to an end. There are two reasons: Its shortcomings are also mentioned above; from technical point, high voltage fast charge basically has no room for improvement, even if there is , it can only improve its efficiency, but the efficiency of the current consumer electronics semiconductor technology is difficult to have a qualitative leap; the other is that Huawei and other brands are now released fast charging technology is low-voltage fast charge, their attitude is actually very specific. Qualcomm, which has been using high-voltage fast charging, has recently released a low-voltage fast charge.
Low-voltage fast charge, there is no doubt that the trend of the future fast-charge development is certainly low-voltage fast charge. What is more difficult to grasp now is the specification of the agreement. For example, if the fast-charging industry has a unified agreement, Huawei’s charger can quickly charge our mobile phone. The agreement has two advantages. One is that it is convenient for users to use it, and the other is to reduce costs. If all mobile phone brands use the same set of agreements, the output of components will increase a lot, and the average cost will drop. However, the prospect of the agreement is not yet clear. It goes without saying that 2018 will basically be the world of low-voltage fast charge.