Fast charging technologies exploit the constant current phase by pumping as much current as possible into the battery before it reaches its peak voltage. Therefore, fast charging technologies are most effective when your battery is less than 50% full but has a diminishing impact on charge time once the battery passes 80%.
Batteries that can charge quickly while also being small, light, and long-lasting would be a step forward. The trade-off between high capacity and fast charging comes down to the way charged molecules called ions move around in batteries. As a battery charges, an electric current pushes lithium ions from one side of the cell to the other.
Therefore, fast charging technologies are most effective when your battery is less than 50% full but has a diminishing impact on charge time once the battery passes 80%. Incidentally, constant current charging is the least detrimental period to the battery’s long-term health.
Because Li-ion batteries may get damaged due to high voltage, manufacturers typically bank on high current transfer rates to fast-charge a phone's battery. Fast charging aims to maximize the constant current flow stage's utility so that maximum charge can be transferred to the battery before the voltage reaches its peak value.
The majority of fast charging standards typically change the voltage rather than boost the amperage to increase the amount of potential energy. Standard USB 3.0 ports output at a level of 5V/1A for smaller devices like wearables. Most phones and other devices are capable of handling at least 5V/2.4A.
The term "fast charging" is used diligently, along with claims about charging a phone's battery fully in hardly a few minutes. If that's not impressive enough, brands also market the wattage at which their phone charges. What does all that mean? A phone's charging capability is defined in watts (W)