On the day of Double 11 this year, at the Tesla Delivery Center in Yizhuang, Beijing, a lithium iron phosphate version of the domestic Tesla Model 3 standard endurance rear drive upgraded version was delivered to the owner, Mr. Zhao.
Prior to this, Mr. Zhao’s JAC iev5 has been in operation for five years, and the 170-kilometer cruising range has always limited his travel radius. Therefore, Mr. Zhao is determined to replace Model 3 to relieve mileage anxiety.
Recalling the trembling scene in the iev5 car in the iev5 in recent winters in order to save the cruising range, the Model 3 seemed to be a long drought for Mr. Zhao, but the performance of the car after the winter let him Disappointed.
“It’s all in 2020, and Tesla’s three electrics are also known as the best. Even if it’s a lithium iron phosphate version, it’s enough to drive to and from work. I didn’t expect Tesla’s electronic control technology to be beyond my imagination. Just 100 kilometers disappeared out of thin air. When the remaining battery life is less than 200 kilometers, as long as you stop for more than 2 hours, you will only have 80 to 90 kilometers left for the next drive.” Mr. Zhao said, “From the time the car was picked up, the battery has never been fully charged. If the subcharge reaches 77%, it can’t be recharged. I went to Tesla’s after-sales service and did a sub-battery balance. It didn’t work at all. It would still fall within 200 kilometers.”
In fact, it is not only Tesla, JAC, BYD, Changan and other independent brand car companies that have lithium iron phosphate models that have such problems. The winter battery life problem of electric vehicles has a long history.
Lithium Iron Phosphate
There is a temperature that makes the battery want to wear long pants.
At present, the power batteries carried by domestic pure electric vehicles are mainly ternary lithium batteries and lithium iron phosphate batteries, and the advantages and disadvantages of both are more prominent.
In the case of the same volume, the ternary lithium battery has a higher energy density and better low temperature performance, but it is not resistant to high temperatures and has a relatively high cost. While lithium iron phosphate batteries have advantages in high temperature resistance, cost, and cycle life, but they have many shortcomings in low temperature performance.
“In the morning, the outdoor temperature was -5 degrees, and I ran about 63km on Beijing Sixth Ring Road. The speed was mostly 80-100. The whole journey was warm. The endurance was reduced by 97km, and the discount rate was about 65%.” Model 3 owner of the lithium iron phosphate version Mr. said.
Because the material activity of the lithium iron phosphate battery is reduced in a low temperature environment, and the number of lithium ions that can move is reduced, the charge and discharge efficiency of lithium iron phosphate models at low temperatures is also greatly affected.
“The iron-lithium version of Model 3 has poor stability in winter. I don’t know if it will be better in summer.” Mr. Ma said, “It’s not the coldest time in winter in Beijing. People who drive ternary lithium battery models say that traffic jams do not cost electricity. It’s true or false. But the lithium iron phosphate model is really costly. I measured it, and it’s currently driving about 1,900 kilometers. From the beginning, it is full of 420 kilometers, and then it is full of about 400 kilometers. Today, it is only 360 kilometers full.”
In response to such problems, Tesla said that it will optimize through OTA. At the same time, in order to display closer to the true value, it is recommended that the owner upgrade the vehicle software to 2021.44.15 or higher, and also provides a method to calibrate the mileage. , And then use the vehicle’s power to below 10%, turn off all additional power consumption functions, stand for more than 3 hours, charge the vehicle to 100%, keep the electric pile connected, and then rest for more than one hour, which will help the vehicle to complete the battery The group is self-balanced and can measure the power more accurately, but the effect is not ideal.
“One night, one night lost 10%, which is about 40 kilometers. Based on the full battery life of 400 kilometers, the customer service said that the calibration method is to park under 10% of the battery for 3 hours, and then park at 100% for 1 hour. This method is really cheating, so it is recommended to buy a ternary lithium battery model, at least it has a long-term test, and the stability is better.” Mr. Ma said.
Among the current models of Model 3 on sale, the domestically produced standard endurance rear-drive upgraded version is equipped with lithium iron phosphate batteries provided by CATL, while the long-endurance rear-wheel drive version and Performance all-wheel drive version are equipped with Panasonic Ternary lithium battery.
“Under normal circumstances, the low-temperature performance of lithium iron phosphate is indeed relatively weaker than that of ternary and lithium cobalt oxide batteries. The current improvements are mainly based on insulation design and thermal management technology, and there is still a lot of room for improvement. Apple mobile phone batteries The low-temperature performance is also not satisfactory. The key to the problem lies in the upgrading of battery technology and thermal insulation measures, which need to be optimized together with the industrial chain.” Yu Pingjiao, Secretary-General of Zhongguancun New Battery Technology Innovation Alliance and Chairman of the Battery 100 Said in an interview with a reporter from the entrepreneurial state.
Studies have shown that under the same low temperature conditions in winter, the cruising range of models equipped with ternary lithium batteries will be reduced by 25%, and lithium iron phosphate models under the same conditions may reach more than 35%. Even Tesla, which is unique in electronic control technology, is no exception.
However, it is not only the lithium iron phosphate battery that is afraid of the cold. The ternary lithium battery models with a nominal range of five to six hundred kilometers do not perform well at low temperatures.
NEDC “Half Cut”
There is a kind of battery life that you can never drive.
At present, the endurance test standard for pure electric vehicles marketed in China is “New European Drivig Cycle Test”, the full name is “New European Drivig Cycle”, or NEDC.
However, during the NEDC test, applications such as air conditioning, headlights, and seat heating will be turned off. During the test, the speed will not exceed 50km/h for urban conditions, and the average speed will be 18.5km/h. The test time It will be around 195 seconds. In suburban working conditions, the state of unimpeded traffic will be simulated. The maximum speed is 120km/h, the average speed is 62km/h, and the test time is about 400 seconds.
Compared with the complex road conditions in reality, NEDC’s endurance test is too simple, and the reference value is not high. In other words, for an electric vehicle with a NEDC battery life of 300 kilometers, due to traffic jams and frequent acceleration and deceleration, the actual cruising range is about 20% off, and the true cruising range is about 200 to 240 kilometers.
According to Puritanism, the current general range of electric vehicles is about 500km, which can basically meet the daily commuting needs of cities. Several models with a battery life of 700km will be launched this year, but the NEDC battery life is too ideal, and it is not suitable for the current technology and market. The battery life under NEDC operating conditions “harms” consumers’ perception to some extent. The actual battery life, especially in winter, is often greatly discounted, which can easily mislead consumers.
Through interviews with car owners, Chuangyebang found that under the test of low temperature in winter, whether it is a lithium iron phosphate battery or a ternary lithium battery, its NEDC range has been “halved.” The winter battery life of electric vehicles faces three major “killers”, and the air-conditioning heater is the number one “killer”.
“The NEDC of Roewe ERX5 is nominally 320 kilometers, and it can only charge up to about 280 kilometers in winter. Because the battery pack is air-cooled to dissipate heat, the charging speed is only 40-50A. The battery capacity is only 48 degrees, and the power consumption is at least 100 kilometers after turning on the warm air. At 25 degrees, the full range of warm air can only be driven for about 150 kilometers.” The owner Mr. Xu told Chuangyebang, “Even if you don’t turn on the warm air, wear a cotton hat, cotton gloves, and a military coat, you can drive at most 260 kilometers. Drive on the highway. Going for an outing is even less, only about 120 kilometers.”
The owner of the car, Mr. Wang, said that since December, the NEDC AION S, which has a range of 510 kilometers, can only drive about 200 kilometers with warm air. The mileage without warm air is only 250 kilometers.
In addition, because many car owners do not have a basement or a slow charging pile to heat the car, part of the battery life must be used to heat the power battery when the car starts, so that it can reach a temperature that can work normally. Some car owners have a short commuting distance, the temperature of the power battery has just heated up to normal temperature, and the vehicle has stopped powering off, resulting in high power consumption per 100 kilometers of the vehicle, and overall battery life is also greatly reduced.
Therefore, cold start of vehicles and short-distance driving have also become the other two “killers” of winter battery life.
“This car has a small battery pack capacity, only 58.8 kilowatt-hours of electricity, and it can be charged once a week in summer. However, when the warm air is turned on in winter, the electricity consumption is at least 22 degrees per hundred kilometers. The car is parked on the ground and the electricity consumption is short-distance. Even higher, a few degrees below zero in the morning cold start the vehicle, the photo battery pack preheating will consume a lot of battery life, sometimes just 200 meters out of the 5 kilometers of battery life.” Mr. Wang told Chuangyebang.
“At present, the iron-lithium version of the Model 3 has run about 240 kilometers in Beijing. The last time it was fully charged, the battery life showed 420 kilometers. The actual run was 241 kilometers. There was 5% of the power left and the power consumption was 39 degrees. It was all short distances in the city. Most of them are less than 4 kilometers from the start to the stop.” said Mr. Che Huan.
It can be seen that in the cold winter, the three “killers” of air conditioning, warm air, cold start, and short-distance driving have brought severe challenges to the winter battery life of electric vehicles. How to better solve the problem of battery life in winter has become the primary issue for the industry and major car companies.
“Quiet” progress
There is a kind of progress, called quietly.
From wearing a military coat and cotton gloves to driving in the past, to now driving with air-conditioning and heating, unknowingly, the air-conditioning, electronic control and power battery related technologies of pure electric vehicles have made certain progress, and such progress has been made. Still going on.
“61% of the electricity came out of the garage and it was 75 kilometers away, the warm air was turned on at 24 degrees, and the power was down 25%. The outdoor temperature was minus 5 degrees Celsius, basically equivalent to minus 5 degrees Celsius, which can last 300 kilometers, and the temperature is about minus 4 or 5 degrees. , The basic energy consumption is 22 kilowatt-hours of electricity per 100 kilometers.” said Mr. Liu, the owner of the flagship Han EV four-wheel drive high-performance version from Qiqihar, Heilongjiang.
Thanks to the advancement of battery technology, after entering the winter, the winter cruising range of pure electric vehicles has been greatly improved in the colder northeast region.
The solid battery life of BYD Han EV has a lot to do with its blade battery.
According to statistics, from January to September 2019, BYD Tang EV ranked first on the list of new energy vehicle sales in the three eastern provinces. It is equipped with BYD’s self-developed ternary lithium battery and has a NEDC range of 500 kilometers.
In addition, in recent years, some car companies have begun to use heat pump air conditioning, diesel heating and other methods on models equipped with ternary lithium batteries to try to alleviate the cruising range problem in winter and have achieved certain results.
Previously, some media had put two pure electric vehicles equipped with traditional PTC air conditioners and heat pump air conditioners. Under the condition of setting the same warm air temperature and air volume, the endurance consumption of models equipped with heat pump air conditioners was only half of that of models equipped with PTC air conditioners.
Some organizations have predicted that in the new energy vehicle air-conditioning market, based on the 10% replacement rate of heat pump systems in 2020, there will be more than 1.6 billion market space, and the 30% penetration rate in 2025 will have a market space of nearly 15 billion yuan. In addition, the market space for ground source, water source, and air source heat pumps for households is larger, but heat pumps for electric vehicles are a new incremental market for auto parts companies, which can provide more growth certainty for companies that are deployed in advance.
Despite the broad market prospects, the higher cost is the biggest obstacle restricting the popularization of heat pump air conditioners. Data shows that the bicycle value of heat pump air conditioners is about 3,300 yuan, which is 1,000 yuan higher than traditional PTC air conditioners.
In addition, the “Diesel battery heating system” of the Weimar EX5 is very practical for consumers in low temperature areas, and can effectively ensure the pure electric battery life of the vehicle, and its use cost is not high. However, some people believe that the diesel-added Weimar models have violated the concept of pure electric vehicles, and are relatively unfavorable to environmental protection and energy consumption.
“From the data provided by some car companies, heat pump air conditioners can indeed save a lot of electricity, but its cost is relatively high and its efficiency is low. Diesel heating methods are currently not used in many models. Electric vehicles are equipped with diesel systems for heating. What a big irony. When we can really solve problems from the perspective of consumers and customers, we will be truly strong.” Yu Qingjiao told Chuangyebang.
While car companies continue to introduce new technologies for winter battery life, the formulation of some industry standards will also provide consumers with more references.
In November 2019, the “China Working Condition” Development and Application Technology Research Conference was officially held in Nanjing. The meeting confirmed that pure electric vehicles will take the lead in adopting China Working Condition (CATC). After 2025, all models will adopt CATC working condition standards.
Zheng Tianlei, director of the fourth room of the Automotive Standardization Institute of the China Automobile Center, revealed that for pure electric vehicles, CATC will delete the constant velocity method and increase the test procedure for turning on the air conditioner at high and low temperatures. The low temperature is set to (-7±3) ℃, high temperature The temperature is set to (30±2)℃, so as to more objectively and truly evaluate the energy consumption and cruising range of pure electric vehicles.
“China’s working conditions are not currently a mandatory standard. Dewatering the cruising range is more conducive to enhancing consumer trust. At the same time, it also forces companies to work harder to improve product performance and accelerate the elimination of backward production capacity. Since 2015, China’s new energy vehicles The production, sales and holdings have ranked first in the world for five consecutive years, and it will also be the most potential incremental market for new energy vehicles in the future. The early realization of the introduction of working conditions in China will also promote the acceleration of the penetration rate of new energy vehicles.” Yu Qing Teach expression.
