Winter Nightmare Of Electric Vehicle Owners

"I've just collected the car for more than two weeks, and the current range is about 280km. To be honest, I'm a little disappointed with the endurance. Although I know that the endurance will shrink in winter, I still get 350 km. " On December 21, Mr. Yang, owner of BYD Han EV in Beijing, told reporters of the 21st century economic report.

As the electric license plate index is about to expire, Mr. Yang bought a BYD Han EV in November with a standard range of 550 km under NEDC conditions. "In recent years, the technology of electric vehicles has improved, but I didn't expect that there would still be mileage anxiety." Mr. Yang said.

Mr. Xiao, the owner of Tesla Model 3, who lives in Haidian District of Beijing, told reporters that charging once a week in summer can satisfy commuters, but now it has to be charged at least twice a week, which is very disturbing.

As there is no underground parking space, Mr. Xiao usually parks his car outside. "When it is below zero, the last night's endurance display still has 200 kilometers left. When I go to drive the next morning, it shows that only 170 kilometers are left, and 30 kilometers are gone. There is no charging pile and no parking space in the room. Driving an electric car is really tiring. "

The reduction of the endurance of electric vehicles in winter brings many troubles to the owners of electric vehicles. In addition to the commuter barriers of private cars, the income of electric taxi drivers has also been affected.

A taxi driver in Beijing told reporters: "if you don't turn on the air conditioner, some passengers will have problems. With the air conditioner on, you can only drive 200 kilometers a day. We like to run long distance big single, make a lot of money, but now sometimes the distance is too far, can't but refuse to carry

Winter seems to be a nightmare for EV owners. Although the endurance of electric vehicles has been greatly improved in recent years, there is still a problem that the endurance of electric vehicles has been greatly reduced in winter, and the range of some electric vehicles has even been cut by half.

"The northern winter endurance shrinkage is a problem that all electric vehicles are facing. It is good to have a 60% discount on NEDC mileage. Consumers in the area north of the Yellow River need to consider carefully when buying electric vehicles. It is better to have indoor fixed parking spaces and charging piles at home. " Some people in the automobile industry told reporters of the 21st century economic report.

In winter, the endurance attenuation of electric vehicles is mainly affected by three factors: the characteristics of power battery, air conditioning and the resistance of rotating system. Figure IC Photo

Why does low temperature become the "killer" of endurance?

"About 20 degrees is the ideal working temperature for electric vehicles. Simply put, the lower the ambient temperature, the more the range will shrink. " Some people in the automobile industry told reporters.

Why does low temperature become the "killer" of electric vehicle endurance? On December 23, Dai Kangwei, vice president of BAIC New Energy Research Institute, told the 21st century economic report that the endurance attenuation of electric vehicles in winter is mainly affected by three factors, namely, the characteristics of power battery, air conditioning and resistance of rotating system.

"As a chemical product, the chemical reactions of battery are all related to temperature." Dai Kangwei said. In brief, the battery power of mobile phone is not durable in winter, so is pure electric vehicle, which is the characteristic of lithium-ion battery itself.

At low temperature, some of the electrolyte inside the battery will become more viscous, including the rate of lithium ion migration and the conductivity of the material itself will further deteriorate, which will reduce the battery activity, thus affecting the battery performance and capacity volatilization. The external performance is the attenuation of the available capacity of the power battery.

That's why the range of electric vehicles that have been stopped for a night will drop.

For example, when parking the previous day, the range displayed on the dashboard is the distance that can be driven under the current comprehensive conditions such as outdoor temperature, battery temperature and condition. However, if the battery is stored at the temperature below zero outside for one night, the battery will become very cold after being shelved for more than ten hours. At this moment, the battery's activity is very low, and the battery's endurance will naturally decrease obviously, sometimes even several tens of kilometers directly.

In addition, as the temperature drops in winter, the resistance of automobile transmission system will change. Due to the increase of air density in winter, the wind resistance and tire resistance of the whole vehicle will increase, and the efficiency of the lubricating grease in the transmission system will also change after the temperature drops. Therefore, the electric vehicle will consume more electricity than other seasons when driving with the same power in winter.

It is worth noting that air conditioning is the "tiger" of electric vehicles in winter, which is related to the energy source of air conditioning.

"In winter, the heat source of the fuel vehicle comes from the preheating of the engine. The conversion efficiency of the engine to power is only 40%, and the remaining 60% heat conversion is enough to meet the heating needs of our passengers. But the electric vehicle does not have the engine preheating, all heating needs energy source Dai Kangwei said.

According to Dai Kangwei, reducing the energy consumption of air conditioning system is the technical direction that electric vehicle enterprises have been striving to improve. Electric vehicles have experienced the early "electric heating wire" and water heating heater, and now the heat pump system, in order to reduce the loss required for heating to a lower level. She revealed that, taking BAIC new energy arcfox α t as an example, using heat pump system can reduce vehicle power consumption by 5-8 percentage points.

In fact, in recent years, in addition to improving the endurance of electric vehicles, car companies have also spent a lot of effort to reduce the efficiency of batteries at low temperatures. For example, heat pump system and battery system are used in thermal management design.

Although the technical strength of electric vehicle has made obvious progress, but in the case of no great change in the power battery material itself, the low-temperature endurance shrinkage of electric vehicle is an objective problem at the production end and design stage.

For the northern electric vehicle owners, in winter, either more charging, or must save in all aspects. It should be pointed out that the service life of power battery will be affected due to excessive charging times. Therefore, saving electricity at the user end is a problem that electric vehicle owners in northern China need to consider.

Some automobile industry experts told the 21st century economic reporter that the simplest way is to park your car in the indoor garage instead of outdoors in winter. At the same time, the car should be charged in time after use every day to avoid standing at low temperature for a long time. In addition, in winter, the vehicle should accelerate slowly and keep driving at a constant speed. Try to avoid sudden acceleration and sudden accelerator, which will lead to frequent high-power discharge of the vehicle.

It is worth noting that many electric vehicle owners find that in winter, the vehicle not only consumes more electricity, but also charges more slowly.

"You can choose to charge in time when the electric vehicle stops running and the battery still has residual temperature, so as to increase the charging efficiency. If it is a self owned charging pile, if the charging gun is still inserted after charging, it has a certain insulation effect. " Dai Kangwei said.

In fact, in addition to the shrinking range, many car owners expressed their concern about the residual value of second-hand electric vehicles when interviewed by the 21st century economic report.

"If you drive an electric car in the north, the service life of the battery will be shorter, and the battery condition will certainly be worse than the cars in the south. Originally, the residual value of second-hand cars is low, and now the cars in the North may have to give a discount. You must be careful when buying an electric car. Now if I choose another car, I may choose a car with electric separation, and my anxiety about the residual value of the vehicle may be reduced. " An electric car owner in Beijing told the 21st century economic reporter.

North Sanyuan, South lithium iron phosphate?

This year, with BYD's blade battery and domestic Tesla Model 3 adopting lithium iron phosphate battery of Ningde era, the battery technology route of pure electric passenger vehicles has been re focused.

Equipped with lithium iron phosphate battery, the cost of electric vehicles can be reduced. However, the winter endurance of lithium iron phosphate battery has also caused a new controversy. Whether it is SAIC GM Wuling Mini EV, BYD Han eV or lithium iron phosphate battery Tesla Model 3, the endurance shrinkage is relatively serious at low temperature.

Many Tesla Model 3 owners said that the lithium iron phosphate version of the electric vehicle endurance shrinkage is more obvious. According to the evaluation data of many automobile industry media, compared with the ternary lithium version, the endurance of Tesla Model 3 of lithium iron phosphate is significantly reduced at low temperature.

"The low-temperature endurance performance of LiFePO4 battery is inferior to that of lithium ternary battery, which is determined by the difference of its own materials. The ternary material is nickel cobalt manganese, which is a layered structure. But LiFePO4 is an octahedral form. Lithium ion in the discharge, the positive and negative electrode back and forth conduction process, the two channels are not quite the same. Hierarchical structure, ion migration is very easy. However, in the process of octahedron migration, the resistance is higher, the activity is lower, and there are some differences in conductivity Some automobile industry experts told reporters.

It is worth noting that in winter, there are still some problems in the charging process of LiFePO4 battery, such as slow charging and insufficient charging. On December 25, Tesla customer officer micro released a message that through software upgrade, the preheating function of LiFePO4 model along the way was optimized. When using the large screen to navigate to the super charging station / third party DC charging station, the vehicle will heat the battery in advance during driving. Before charging, let the battery reach the ideal temperature close to the lithium electronic activity to improve the charging efficiency and charging speed.

Some people believe that in contrast, it is more appropriate to choose electric vehicles equipped with ternary lithium batteries in the north.

"Taking Wuling Hongguang Mini EV as an example, consumers' psychological expectation is low price oriented and more acceptable. However, there is a certain gap between these models with a price of 200000 + from the perspective of consumer psychological demand. I personally think that with the Yellow River as the dividing line, large vehicles in the North (with higher service quality above grade B) are more suitable for the use of ternary cells. Lithium iron phosphate batteries will bring some challenges to users and are easy to collapse in winter. " Zhu Yulong, an expert in the automobile industry, finally said.

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