What exactly is Fast Charging? And how does it work?

Gyang Peter · 发表于 2019-04-04 01:30:35

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[br][br]The mention of fast charging technologies for smartphones has become quite common lately. You’ve probably already heard of Qualcomm’s Quick Charge, OPPO’s VOOC flash charge, or OnePlus’ Dash Charge, which can juice up a smartphone’s battery to around 60 percent in just 30 minutes. So, how exactly do they work?[br][br]Most devices use lithium-ion batteries[br][br]To understand how these technologies work, knowing the basic principle of how a smartphone’s battery gets charged is a must. Most, if not all, smartphones today use a type of battery called lithium-ion (Li-ion). A Li-ion battery is composed of a positive and negative electrode and an electrolyte in between them. The lithium ions inside the battery move from one electrode to another, allowing the battery to be in a charging (storing energy) or discharging (expending energy) state.[br][br]Battery capacity is measured in milliampere hour (mAh)[br][br]Great, we’ve got some background on how Li-ion batteries work! The next question is how exactly do we determine the speed at which a Li-ion battery gets charged. You’re probably familiar with the rating used to gauge the capacity of a smartphone’s battery. If not, it’s the number that uses mAh (milliampere hour) as its unit of measurement. A larger number means larger capacity, which translates to longer battery life.[br][br]A 6000mAh battery will last twice as long as a 3000mAh battery. The same thing applies to charging: The larger the capacity of a Li-ion battery, the longer it takes to fully charge. The amount of current that the charger can output is usually the determining factor on how fast a battery can be charged, which is why a tablet charger that can output 2A (ampere) will charge twice as fast as a smartphone charger that can output 1A.[br][br]Another important nature of a Li-ion battery is that it doesn’t charge in a linear fashion. It’s easier to charge the battery when it’s nearly empty compared to charging when it’s nearly full. Think of it like packing a bag; it gets harder to put things in as it gets filled.[br][br]As mentioned, increasing the current used to charge a battery decreases charging time, but only up to a certain point. A Li-ion battery can only take in so much current, and increasing it past the threshold only results in dissipated energy in the form of heat. Therefore, if you use a tablet charger to charge a smartphone, it usually charges faster but also heats up faster.[br][br]Battery charging has evolved through the years[br][br]With all these things in mind, we can go back to the question of how fast charging technologies work. As its name implies, it allows rapid charging of a smartphone’s battery. This is usually done by increasing the power output of a charger, either by increasing the voltage or current that it provides to the device. You might ask if it’s safe to increase the amount of power we pump into our devices: Theoretically, it isn’t safe, but with the right hardware for monitoring and checking power output and temperature, things become safer.[br][br]Qualcomm’s Quick Charge gets better every year [br][br]Qualcomm’s Quick Charge technology leverages on different power outputs — mostly voltage adjustments — for the charger, depending on the current battery capacity of the device. Thanks to the special chip installed on both the device and charger, the latter can actively adjust the power output depending on the device’s needs. So, at lower capacities, it delivers the highest power rating the device can safely handle, and as the battery gets more juice, the device communicates with the charger and tells it to provide less power.[br][br]Ever since Quick Charge was introduced, Qualcomm has continued its development and currently has five iterations: Quick Charge 1.0, 2.0, 3.0, 4.0, and just recently, 4+. Here’s a table to summarize what the first four iterations of Quick Charge are capable of:[br][br][br]

[br][br]Quick Charge 4.0 builds on the success of QC 3.0 by adding new features: compliance to USB Type-C and USB Power Delivery; a newer version of Intelligent Negotiation for Optimum Voltage (INOV), allowing the device to determine the optimum power level to request from the charger; and the inclusion of Dual Charge which adds a secondary power management chip in the device for better thermal dissipation and more efficient charging.