The principle is not complicated, is to add adjustable temperature heating body inside the cushion, as long as the cushion is connected to the car power supply, the cushion can heat.
It is worth noting that the price gap of this product is very large, online cheap dozens of yuan, expensive up to thousands of yuan. At present, the market price of dozens of yuan of car heating cushions are basically directly attached to the cigarette light device, this practice is easy to burn the fuse. There are also some car heating cushions, not directly connected to the cigarette point, the installation process will also change the line, and the voltage limit of each car is specified, once the addition of new resistance, may cause the car current short circuit, serious will also cause fire. Therefore, it is not recommended that a family of cars install such heating cushions at will.