The cold winter has made the winter mileage anxiety problem of new energy vehicles become prominent again, and how to alleviate the shrinkage of mileage or even jump into a major pain point for consumers.
On December 31, China Automotive Engineering Research Institute Co., Ltd. released the "White Paper on Low Temperature Endurance of China's Small New Energy Vehicles" (hereinafter referred to as the "White Paper"), based on the low temperature attenuation data of 53 new energy vehicles, the average value and distribution range of the low temperature mileage retention rate of new energy vehicles have not changed significantly during the period from 2012 to 2020.
The data shows that more than half (65.4%) of the vehicles have a low-temperature mileage retention rate of about 52.8%-67.2%, and the median value of their normal distribution is 59.95%. It is worth mentioning that the category performance of small new energy vehicles is better.
Wang Zidong, an expert of the New Energy Vehicle Production Access Review Group of the Ministry of Industry and Information Technology, revealed that at present, the industry generally adopts physical or chemical methods to improve the low-temperature use experience of batteries, and the Ministry of Industry and Information Technology is also advocating the promotion of power exchange mode to win time for new battery technologies.
The low-temperature attenuation characteristics of lithium-ion batteries cannot be avoided
The characteristics of lithium-ion batteries determine their low-temperature attenuation characteristics. The working mechanism of the battery is similar to that of the "rocking chair" electrochemical energy storage away, and the low temperature environment reduces the activity of lithium ions. At the same time, through the battery environmental resistance charge and discharge curve, it can be seen that the low temperature environment has a significant impact on the usable capacity and charge and discharge performance of the battery.
"The low temperature attenuation characteristics of the battery cannot be avoided, which is an important factor affecting the attenuation of the vehicle's mileage." Wang Peng, head of the new energy evaluation regulations of The China Automobile Research Institute, who participated in the drafting of the White Paper, pointed out.
In addition to the energy point of view, from the perspective of vehicle use, Wang Peng said that driving at low temperatures, the decay caused by vehicle operation and use is common. When driving in winter, vehicle drag increases, thermal management system power consumption increases, and the need for crew cabin heating increases.
Measured data show that at -7 °C, PTC consumes 10.36kWh of power, accounting for 20.2% of the battery pack energy.
Based on the low-temperature mileage retention rate data at home and abroad in the past 10 years, the average value and distribution range of the -7°C low-temperature test mileage retention rate of 53 new energy vehicles have not changed significantly during the period from 2012 to 2020.
Not only is the low-temperature mileage retention rate of more than half (65.4%) of the vehicles at about 52.8%-67.2%, and the median of its normal distribution is 59.95%; at the same time, the common problem of "low temperature endurance anxiety" objectively exists in new energy vehicle products at home and abroad, but the level of products of different enterprises varies greatly.
Small cars outperformed the industry average
The problem of low-temperature mileage retention rate of new energy vehicles is difficult to break through in the short term, but the data of the "White Paper" also shows that small cars have more advantages in comparison.
In a test conducted by China Automobile Research Institute, the -7°C WLTC (I.+II.) mileage retention rates of the two Wuling Hongguang MINI EVs were 64.6% and 67.5%, respectively. Compared with the industry median level of 59.95%, it increased by 7.7% and 12.5% respectively, which is at the leading level in the industry.
The "China Small New Energy Passenger Car Travel Big Data Report" shows that the average mileage of small new energy vehicles is 7.63km, and the average daily mileage is 30km, which is more suitable for users of cities and suburbs, low-speed and short-distance travel.
Also in this report, the definition of small new energy vehicles is an A00-level and A0-class new energy vehicle with the on-board battery as the power output, the motor driving the vehicle, and the requirements of road traffic, safety regulations and national mandatory standards. At present, the models on the market include Baojun E300, Zero-run T03, Chery eQ1, Euler Black Cat, SAIC Coleway, Hongguang MINI EV and other models.
Ouyang Minggao, academician of the Chinese Academy of Sciences, professor of Tsinghua University and deputy director of the academic committee of the university, believes that the most obvious advantage and the highest market share of fuel vehicles are small new energy vehicles. "The low-temperature mileage retention rate of mature small new energy vehicles can be controlled at a better level, which can meet the average daily driving demand in winter in North China." Wang Peng pointed out.
Promote the power exchange mode to buy time for technology
At present, there are four main ways to solve the winter endurance anxiety of new energy vehicles - first, to improve the electrochemical properties of the existing material system, especially the problem of low-temperature activity; second, actively look for better low-temperature materials; third, physical ways to heat the battery; fourth, it is to replace it with the mode of power exchange.
Wang Zidong pointed out that in view of the cold winter of the past two years, daily operating vehicles are "the most sensitive" to the problem of battery life shrinkage, and such vehicles with high frequency daily use and large battery mileage consumption are more suitable for power exchange mode.
"Changing the power supply is to buy time for our tech community to at least ensure that it will work until no new materials are discovered, while allowing scientists to actively find better methods." He stressed.
However, when choosing what way to deal with low temperature endurance, enterprises should also consider cost and technology. "Some battery low temperature problems are solved, high temperature may also encounter problems, so it is necessary to consider comprehensively, while effectively improving the low temperature of the battery actually corresponds to the increase in cost, and enterprises must consider it comprehensively." Xiao Chengwei, a research expert at China Electronics Technology Group, said.
On the other hand, Wang Peng also suggested that the majority of new energy vehicle consumers should also pay attention to some car specifications when using cars in winter to effectively improve the car experience.
He suggested that car owners should use air conditioning reasonably, and can turn on seat heating instead of using air conditioning; for vehicles equipped with battery heating systems, they should be preheated in advance before driving; when parking, they should be parked in the garage as much as possible to reduce the impact of low temperature on power battery discharge and reduce the loss of mileage.
At the same time, car owners should also develop the habit of charging with the use to avoid excessive discharge; choose a suitable charging environment and avoid DC fast charging to reduce the risk of lithium evolution caused by low-temperature and high-current charging; develop soft winter driving habits; try to avoid sharp acceleration and sharp deceleration to reduce the battery discharge rate in low-temperature environments, improve braking energy recovery rate, extend the cruising range, etc. (Text/Tencent Auto Zhang Cuicui)