A few days ago, our 58 automobile organized a test to test whether pure electric vehicles can be used normally in a low temperature environment of minus 20 ° C in order to be close to the real car environment of users. Through the comprehensive test of static and dynamic two parts, see if pure electric vehicles with different positioning and different prices will be in a state of flux in this extremely "unfriendly" adversity, or even simply strike.
It should be emphasized that this test is not a comparison between each model, but by showing the performance of these cars in the same test environment, it gives readers a certain reference role in selecting and buying cars, and find models that are more suitable for themselves.
Among the 6 models, there are both high-end Weilai ES8, Audi e-tron, Polestar Polestar 2, as well as the more cost-effective Xiaopeng P7, Tesla Model 3, and Nezha U Pro. The front group happens to be a four-wheel drive model, and the rear group is all two-wheel drive.
The test vehicles were all replaced with snow tires with short nails, which was conducive to improving the grip of the vehicle on the ice. And because weilai ES8 and Nezha U Pro can not find a snow nail tire that perfectly matches the size of the original factory, so the tires of the two cars are slightly different from the original factory size, the tire width of the Weilai ES8 has reached 295, and the grip is stronger than the original factory size, and although the tire width of the Nezha U Pro is consistent with the original factory, the flatness ratio is smaller than the original factory, so the tire circumference is slightly reduced, and there is a little deviation between the instrument speed and the speed of the test instrument in some projects.
In this test, we arranged two parts: low temperature static comprehensive test and ice and snow dynamic performance test, so as to test the comprehensive use status of the vehicle in the low temperature environment of minus 20 °C, and simulate the real use environment of the user. The first is the low temperature static comprehensive test, which is divided into three test items: low temperature charging speed, battery low temperature attenuation and air conditioning heating speed.
1. Low temperature charging speed test
Before starting, we first let 6 cars sit at minus 20 ° C overnight and let the vehicles cool down completely. At the start of the test, each car used the same DC fast charger pile and recorded the initial data as well as the charging data for 15 minutes and 30 minutes. At this time, the remaining power of the battery of the 6 cars is basically maintained at about 50%, which meets the conditions for the vehicle to start fast charging.
From the actual data we recorded, all vehicles have a tendency to significantly reduce the charging speed and greatly increase the full charge time in the low temperature environment. After all, in such a low temperature, the power battery has been unable to maintain a normal working state, and it takes a certain amount of time to complete the self-heating process.
Specific performance, Audi e-tron, Polestar Polestar Polestar2, Nezha U Pro and Xiaopeng P7 can complete the battery self-heating in a relatively short period of time and gradually increase the charging speed, while the Weilai ES8 and Tesla Model 3 can not quickly complete the battery self-heating in 30 minutes, only slowly replenishing a single-digit percentage of the power, to fully charge the battery, it takes more time.
2. Battery low temperature attenuation
At the beginning of the battery low temperature attenuation test, the vehicle is charged to 90-100% of the full power state and the battery charge data is recorded, and after standing overnight in the minus 20 ° C environment, the vehicle is started again to view the battery power data, and by calculating its difference, check the self-consumption of the vehicle at low temperature.
Among the 6 models, the battery power percentage of Audi e-tron and Xiaopeng P7 has not changed, but the meter mileage has decreased, we believe that this is directly related to the endurance calculation strategy of the vehicle itself, the computer directly converts the power required for self-heating, and deducts the corresponding mileage, not its own serious power failure.
(The picture shows the Xiaopeng P7 test data)
The power percentage and meter mileage of the three models of Weilai ES8, Polestar Polestar Polestar and Nezha U Pro have decreased slightly, which basically belongs to the range of normal consumption. Of the 6 models, only Tesla Model 3 dropped 4% of the power, significantly higher than the other 5 models, in addition to excluding the opening of the sentinel mode, the appointment to open the air conditioning and other factors, we think the reason may lie in the reason of the Model 3 itself, this test drive for the domestic early model, not the latest model, has traveled nearly 30,000 kilometers, the power battery has a certain natural loss, so in the case of full power there is such a decline is also normal.
3. Air conditioning heating speed
The final static test is the air conditioning heating speed test, which tests the heating capacity of the vehicle's air conditioning system at low temperatures. The heating temperature and wind speed of the air conditioner are adjusted to the maximum throughout the test, so as to test the performance of the air conditioner at the maximum heating power. We record the initial temperature and the values after 5 minutes and 10 minutes respectively to see if the vehicle can alleviate the cold inside the car like an ice cellar in a short period of time. It should be noted that the maximum range of the thermometer we use is only -10 ° C, and then it is directly displayed as L (LOW), so we temporarily decided to use the temperature display of the vehicle as a reference.
(After freezing overnight, the vehicle has obvious frost, and the inside of the vehicle is very cold))
From the actual test results, the standard heat pump air conditioning of the Weilai ES8 performance is quite fierce, after 10 minutes to increase the temperature in the car to the highest 5.9 ° C, to know that the WEILAI ES8 is facing the largest space in all models, that is to say, its heating load is also the largest, but also so eye-catching, it is indeed admirable.
(Nezha U Pro test score)
Of course, the lowest price in the whole field and only equipped with PTC heating function Nezha U Pro is also very outstanding, 10 minutes after the heating temperature followed by Weilai ES8, it seems that as long as you are willing to use electricity, heat pump air conditioning is not everywhere leading. The performance of the other four models is not much different, the temperature inside the car is basically increased to more than 0 ° C, if you continue to test, I believe that the car will soon be warm as spring.
This concludes the comprehensive testing of low temperature statics, and then an even more exciting test of dynamic performance of the ice surface begins. It is divided into five parts: low temperature endurance test, ice surface elk test, ice surface steady-state winding test, 0-60km/h acceleration test and 60-0km/h brake test. Simulates the daily driving of the user and tests the vehicle's vehicle driving performance in an emergency state.
1. Low temperature endurance
First of all, the low temperature endurance test, different from the test method of the friendly media, we use the method of recording the maximum mileage that the vehicle can travel when it consumes 10% of the battery power. The test was conducted on an ice and snow track about 1 km long and the air conditioning was turned on throughout, and the temperature was adjusted to about 24 °C. All 6 vehicles are the same driver, and the driving method is violent driving, which tests the actual endurance performance of the vehicle at low temperature and high power output.
However, it is precisely because of this extreme way of using the car, all cars have a serious rapid power loss, the meter mileage and the actual mileage have a huge deviation, even if the smallest difference in the Xiaopeng P7, its table mileage drop is also higher than the actual mileage of 4 times.
In this project, the Audi e-tron not only has the fastest power loss speed, but also has the shortest driving range of 10% of the power, and the reason for the loss is that it uses a four-wheel drive system, and the battery capacity is small, self-important, etc. Although it seems to be the biggest loss in this project, all of our colleagues who tested the project agree that this car is the most fun to play on the track, and the best to control, if there is a driving pleasure selection, this Audi e-tron is definitely a well-deserved champion.
With e-tron along with the loss of Weilai ES8, self-major, four-wheel drive is also the reason for power consumption, but the same four-wheel drive Polestar Polestar Polestar 2 is not so expensive, it seems that the efficiency of each home control system and the difference in driving energy consumption performance is still quite large, if you are very concerned about the mileage, some models should be carefully considered.
2. Emergency obstacle avoidance ability
The second dynamic item is the ice surface elk test, the test standard refers to ISO 3888-2, although this is a set of pavement-based test methods, but the 6 models are also based on the unified method of testing, so they are relatively fair to each other. Moreover, this test also tests the vehicle's ability to avoid obstacles on the ice surface in an emergency, and has certain practical reference value. What needs to be added is that the test site of this project is a frozen lake, the surface area snow is relatively thin, and the vehicle in the test is facing a mixed road surface of ice + snow surface, which can provide friction that is much lower than that of the thick snow road, so the critical speed of the vehicle during the test is also lower, and the sliding comes earlier.
In practical tests, all vehicles were able to complete emergency avoidance at speeds of 25km/h and 30km/h, and the real watershed began at 35km/h. In this project, 4 SUVs with a high center of gravity failed to pass the test, the e-tron with a four-wheel drive system and the lighter Nezha U Pro regrettably encountered a pile bucket, while the Weilai ES8 and Polestar Polestar 2 both left the field with the result of flying three pile barrels.
In the sedan, the Model 3 and Xiaopeng P7 not only successfully passed the 35km/h project, but also passed even in the 40km/h group of the additional test. In general, in this kind of grasp is king project, who has a lower center of gravity, who has a small driving inertia, who has more advantages, and the four-wheel drive system is basically not helpful in this project.
3. Ice surface steady-state circle
This project is usually less common, here to explain: all vehicles in the same direction around the diameter of about 40 meters of the ring circle, when the test car can complete the full circle without correcting the direction of the premise, the test officially began, at this time no longer allowed to correct the direction and gradually speed up the vehicle, until the vehicle can not resist the role of centrifugal force and out of control, for the model that can not close the body stability system, we take the speed of its intervention as the evaluation standard. This test method mainly examines the control limit of the vehicle in the corner, the higher the speed before the loss of control, indicating that the greater the pressure that the chassis can withstand, and the higher the limit of vehicle control.
Specifically, with the help of the four-wheel drive system, Polarstar Polestar Polestar, Audi e-tron and Nio ES8 have a very obvious advantage, the runaway speed is significantly higher than the other three two-wheel drive models, Weilai ES8 is trapped in its own weight and high center of gravity, regret to take the lead in exiting, and the two rear-drive cars in this project at the bottom is also a loss in the drive structure, after all, the easiest to shake off the tail, is the rear drive.
4.0-60km/h acceleration
In the 0-60km/h acceleration competition, the level of absolute power is not the most important, but whoever has the strong grip will run fast, so it is not surprising that the three four-wheel drive SUVs have an absolute advantage to get the lead. After all, in the four-wheel drive state, all four wheels can forward output driving force, while two-wheel drive models have only two drive wheels to do positive work, and at the same time, they have to drag two driven wheels that do negative work, and the efficiency will inevitably be greatly reduced.
It can be seen that the front-drive Nezha U Pro is quite a loss in this project, the first wheel is crazy and slippery at the beginning moment, and the rear wheel is calm and relaxed, which has the appearance of me not moving. Tesla Model 3 adopts a very conservative output strategy, since it slipped with a hard time, then I simply took it slowly. Although the Xiaopeng P7 has a larger self-weight, the slightly larger tire width and relatively more accurate electronic system calibration bring a little advantage, and the acceleration is more relaxed.
5.60-0km/h braking
Finally, there is the braking performance of 60-0km/h, in this project, all models are almost at the same level, the best performance of the NIO ES8 is mainly the advantage of larger tire width, while the performance of other models is not much different.
It is worth noting that even if these models with nail tires are only braked at a speed of 60km/h, the braking distance is almost the same as the braking distance of 100-0km/h on ordinary paved roads. In other words, braking on the ice at the same speed will be much higher than the ordinary paved road, and if you want to drive safely, you must slow down. In addition, if you want to stand on the ice and snow road, you must also try your best to improve your grip.
(NIO ES8 acceleration and braking results)
With the above test, let's make a summary. All new energy vehicles are very afraid of cold, especially in terms of charging speed and mileage reduction speed, which is very different from warm environments. That is to say, with the current technical conditions, no matter what the price of electric vehicles is not suitable for use in the cold environment. Unless you have the ideal car conditions for warm storage at both the origin and destination, the single mileage is not long, and the charging is convenient, if you can meet them, there is not much inconvenience in choosing a pure electric vehicle.
For the dynamic driving performance on the ice and snow road, the difference between electric vehicles and fuel vehicles is not so big, both are acceleration performance, braking performance and extreme handling performance compared to the paved road surface significantly reduced state, and the larger self-weight is more unfavorable for dynamic comprehensive driving performance, driving needs to be more careful. In addition, four-wheel drive (all-wheel drive) can provide better comprehensive control in comparison, if possible, please try to choose the four-wheel drive version.
Well, the ice and snow test part of this new energy vehicle will be temporarily over, and then we will take these cars back to "warm" Beijing to see how they will perform in the city.