40w is a fast charge.
< br >
40w fast charge means that the power reaches 40w fast charge. 40w fast charging is faster than the traditional charging, the charging time is greatly reduced, and the charging efficiency is greatly improved. The greater the power, the stronger the charging capacity. Power is the product of voltage and current, and the charging voltage of the mobile phone is generally 5 volts or 9 volts, under the same voltage, the greater the power represents the greater the charging current, which is equal to the faster the charging speed.
Electrical power. The higher the power, the faster the charge. P(power) = U(voltage)×I (current) Traditional fast charge is generally 5V-2A, the charging head is generally marked, its power P = 5×2 = 10W. The 40W fast charge is 4 times the traditional fast charge.
According to the current fast charging technology, 40w can only be considered fast charging