Reason 1: The resistance of the charging line is large. According to the heating formula of the conductor, the heat output is equal to the current squared times the time multiplied by the resistance. It can be seen that the greater the resistance is, the greater the heat output is when the charging current is consistent.
Reason 2: When using fast charging, the heat generated by the increase of current also increases, for example, if the heat generated by 1A current charging is compared to 1, the heat generated by 2A charging is four times that of 1A.
Reason three: the charger heat leads to heat conduction to the wire, the charger in the charging time is there is a certain conversion rate, the general conversion rate of about 80%, the rest of the energy in the form of heat divergence, and the charging line in the copper wire is a good conductor of heat leading to the charging line is also hot.