With the safety factor, it is best not to use it for a long time.
The USB fan mainly relies on a micro motor, and the USB interface of the computer can provide 500 to 1000 mA current, which can make the motor operate. Computer damage is mainly because the voltage and current value of the USB interface is not constant, often fluctuate according to the use of the computer, once the power supply current is unstable, it will cause electrical failure, and then damage the computer.
In the past two years, USB small appliances have been frequently used, in addition to summer fans, and winter hand warming treasure, hand warming mouse pad, etc., can be charged directly with the data cable. However, when using a computer to charge, USB electrical damage is a small matter, if the computer is involved, the entire computer motherboard has to be disassembled and repaired, the cost is very large. If you use a computer to charge USB appliances, you must be pulled out in time when charging is complete, if you are not beside the computer for a long time, it is also best to unplug the data cable.
It's safe to use all the time.
The electric fan of the usb port is generally a small power fan, the current is not large, the use of 40w charger head for this small fan for a long time power supply for a night, the general problem is not large. It's also hotter in summer. Before going to bed, it is recommended to unplug, because after sleeping, in case there is a problem, you know nothing about it, it is not safe.
It's not safe. It overheats and burns
USB fans are still safe and use very little power
Always using the motor and USB interface will heat up, easy to burn the fan, and the USB port will also be damaged