Important Facts about quick charging in Android

Fast charging is believed to cause damage to both the short term and long term health of battery. A common feature while using fast chargers is raise in temperature of battery as more current is used in and power is proportional to square of current and this is harmful to the health of battery.
A discharge/charge cycle is commonly understood as the full discharge of a charged battery with subsequent recharge, but this is not always the case. Batteries are seldom fully discharged and manufacturers often use the 80 percent depth-of-discharge (DoD) formula to rate a battery, meaning that only 80 percent of the available energy is delivered and 20 percent remains in reserve. Cycling a battery at less than full discharge increases service life and manufacturers argue that this is closer to a field representation because batteries are commonly recharged with some spare capacity left.

Qualcomm Quick Charge 2.0 supported four modes at varying power levels, 5 volts/2amps, 9V/2A, 12V/1.67A, and 20 volt option.
Qualcomm Quick Charge 3.0 has major new feature INOV (Intelligent Negotiation for Optimum Voltage), which provides fine tuned power output and a more optimized charging cycle. Quick Charge 3.0’s INOV communicates with the device to request any voltage between 3.2V and 20V at 200mV increments, allowing for a best selection of voltages. INOV has the advantage of being able to dynamically adjust the charging voltage over the battery charging cycle.

This granular variation of voltage to control power, results in 27% faster charging than Quick Charge 2.0 (2x faster than the original Quick Charge 1.0) while reducing power dissipation by 45%. It also increases power efficiency by 38%, and being good to the battery life cycle. Granular fine control on voltage and in turn on power supplied for charging is the key innovation that results in these improved figures. Qualcomm Quick Charge 2.0 had only one voltage level relevant to mobile devices- 5V, whereas Qualcomm Quick Charge 3.0 has 9 variations possible from 3.2V to 5V in steps of 200 mV. This granularity offers greater control on power delivered for charging in a dynamic manner as required. Quick Charge 3.0 will be backward compatible with the technology's previous iterations, and can be implemented with USB Type-C, USB Type-A, MicroUSB, and proprietary connectors.