As the weather becomes colder, the tram endurance becomes shorter, mainly for the following reasons:
Ⅰ. Battery performance is affected by temperature:
a. Reduced battery activity: at low temperatures, the chemical substances in the battery react slowly, and the fluidity of lithium ions becomes worse. It becomes difficult for lithium ions to pass through the diaphragm, and the number of lithium ions in the positive electrode is reduced, resulting in lower discharge capacity, reduced energy output of the battery, and correspondingly shorter mileage. In the case of extreme low temperature, there will even be a freezing of the electrolyte, the battery can not discharge and other phenomena, seriously affecting the battery performance.
b. The internal resistance of the battery increases: when the temperature decreases, the resistance inside the battery will increase, and the energy consumed by the battery itself will increase during the discharge process, and the energy used to drive the vehicle will decrease, which will affect the driving range.
Ⅱ. Energy consumption for heating inside the car: In cold weather, in order to maintain a comfortable temperature inside the car, the trolley needs to consume the energy of the battery for heating. Compared with cooling, heating consumes much higher energy. As a result, the energy used to drive the vehicle is correspondingly reduced, resulting in a decrease in range.
Ⅲ. Reduced energy recovery efficiency: Trams often have energy recovery systems that convert kinetic energy into electricity and store it back in the battery when the vehicle slows down or brakes. However, in the low temperature environment, the efficiency of the energy recovery system will be affected, and the recovered energy will be reduced, which will also affect the range of the tram to a certain extent.
Ⅳ. Increased riding resistance:
a. Tire pressure changes: the temperature drops, the air in the electric vehicle tire expands and shrinks, resulting in smaller tire pressure, increased tire contact area with the ground, increased friction, and increased resistance to overcome when the vehicle is driving, thus consuming more energy and making the driving range shorter.
b. Increased wind resistance: in winter, people wear thicker clothes, the use of windshields and other conditions will also increase the wind area of the vehicle, and the faster the speed, the greater the wind resistance, the more obvious the power consumption of the vehicle when driving.