Why is the USB Charger plug hot?

When the mobile phone is charging, it is normal for the USB Charger to heat up, 

and there is loss in AC and DC power conversion. Generally, the USB Charger uses

 a high-power switching power supply, but due to its size, there is basically no PFC

 circuit, so the power factor is only 0.7. The rest of the energy is basically transformed 

into heat energy.

 

It is normal for the USB Charger to be a bit hot during charging, as long as there is no peculiar smell, 

just ignore it. Since heat will accelerate the aging of electronic components, it is best to put it in a ventilated

 place.

Is it normal that the head of the USB Charger is particularly hot?

 

At present, the area of the transformer core of the USB Charger is too small. In addition, it is normal for the

 components to generate high power. If you are hot, you must stop for a while before charging to avoid burns

 or explosions.

1. High voltage constant current mode: The charging process of a general mobile phone is to first reduce the 220V

 voltage to the 5V charger voltage, and then reduce the 5V USB Charger voltage to the 4.2V battery voltage. During 

the entire charging process, due to the increased voltage and heat generation, the USB Charger will heat up during 

charging, and the mobile phone will also heat up. In this way, the greater the power consumption, the greater the damage

 to the battery.

 

2. Low voltage and high current mode: In the case of a certain voltage, to increase the current, you can use a parallel circuit

 for shunting. At a constant voltage, after parallel shunting, the smaller the pressure shared by each circuit is, it is also performed 

in the mobile phone. In the same way, the pressure on each circuit will be less.