There are so many electric vehicle endurance standards, which is not a false standard?

Answers announced: EPA>wlTP> NEDC>CLTC

Some time ago, a classmate asked me that I now have so many battery life standards for electric vehicles, which one should I believe? Indeed, from the NEDC that people know before to the CLTC that many car companies have begun to use, there is more than one standard for endurance, and in the eyes of many people, NEDC is already very "virtual standard", and now it is even more unclear how much the actual endurance can be reached? Today, as an electric vehicle owner, I will talk to you about the electric vehicle endurance standard.

Why is the most commonly used battery life standard now NEDC?

Before that, let's take a look at NEDC's evaluation criteria: NEDC's range test mainly simulates urban and suburban environments, accounting for 4:1 respectively. The first is the urban condition, which simulates the urban condition from 0 to 780 seconds, accelerating, maintaining the speed, decelerating, stopping, and repeating it four times during the test. The second condition, the suburban condition, is tested from the 780th second, and the suburban condition gets off the car significantly faster than the urban condition.

Although the NEDC test seems to simulate a certain amount of usage, in fact, most of the daily use is not simulated at all, after all, the working conditions in urban areas and suburbs are not as simple as speed. And in addition to the use conditions do not meet the daily driving habits, the NEDC standard for the consideration of wind resistance factors is also relatively "perfunctory".

Because nedc's test is basically a bench test, only a blower is placed in front of the front of the car, and its main purpose is to simulate air flow equivalent to the current speed. However, this practice is really too "perfunctory", resulting in the impact of wind resistance on the vehicle's endurance is not convincing. It should be known that the impact of wind resistance on the endurance of electric vehicles is also considerable, otherwise there will not be so many pure electric new cars that repeatedly emphasize their wind resistance coefficient when they are released.

In fact, we also tested the impact of the wind resistance coefficient on the endurance during the previous test drive, we used the Xiaopeng G3 with a wind resistance of 0.31Cd and the Xiaopeng P7 with a wind resistance coefficient of 0.236Cd to run the distance from Beijing to the river under the same conditions, including 30% of the urban road section and 70% of the high-speed section, and finally the Xiaopeng G3 table showed that the endurance was 40km more than the Xiaopeng P7 (including a certain vehicle weight and other factors). Therefore, because the actual road conditions have more environmental impact factors, but the NEDC working conditions consider too few factors, so the data concocted by this theory is sometimes far from the facts, and the reference significance for the actual endurance is not large. However, why are most car companies still using NEDC conditions to calibrate the battery life of their own cars?

Because the Ministry of Industry and Information Technology of China uses the NEDC test standard for the comprehensive mileage test of pure electric vehicles, most car companies generally use the NEDC standard. But in fact, the full name of NEDC: New European Driving Cycle, Chinese means "New European Driving Cycle". As you can tell from the name, this is the European endurance test standard. And the NEDC standard was designed in the 1980s and adopted in 1990. The last update was in 1997. The goal is to replicate the typical use of European cars, which is too "far away" from the actual use of modern electric vehicles.

How "fictitious" is NEDC?

Now that you know how outdated NEDC endurance is, do you know how "fictitious" NEDC conditions are? Let me tell you with another quiz.

In this experiment, we used the same vehicle and the same road environment and use environment for testing, and the specific test content is detailed in our video "The same road, NEDC and WLTP drop the difference in electricity is so big!? 》。 By comparing the data, we can find that the battery life discount rate of Xiaopeng P7 under NEDC conditions is actually 68%, while the endurance discount rate under WLTP conditions is only 85%, such data performance Do you dare to believe NEDC?

On the basis of reliability, we have to look at WLTP at present

After knowing the false label of NEDC, I have been using another set of endurance standards of Xiaopeng P7, WLTP, which will be "reliable" than NEDC, but the corresponding endurance of your table will also shrink. For example, my Xiaopeng P7 in the NEDC charged to 90% endurance meter display is 603km, and to WLTP condition charged to 90% meter display is only 513km, but in the spring and autumn this kind of warm weather and do not need much air conditioning climate, WLTP conditioning performance can almost do not discount, or has a certain credibility.

So what is WLTP? The full name of WLTP is World LightVehicle Test Procedure, Chinese meaning "World Lightweight Vehicle Test Procedure". Its biggest feature is that it relies heavily on monitoring data from real-world drive cycles, while at the same time generating a higher degree of feedback on the road surface. The WLTP test program covers four operating conditions: low, medium, high and ultra high speed. The average speed of the test was 46.5km/h, and the maximum speed was 131.3km/h. Unlike NEDC, the WLTP uses a non-fixed mode of gear change, but instead changes different drivers to simulate the real situation. External temperature, car quality, gear status, rolling resistance, load, acceleration and deceleration and other factors have been included in the assessment system, so the authenticity of the overall test results is much higher than that of NEDC.

CLTC is in line with the national conditions, but it is currently more "virtual" than NEDC

In addition to the above NEDC and WLTP, there is currently a new endurance standard - CLTC, full name China light-duty vehicle test cycle, that is, the driving conditions of China's light vehicles, which is said to be more in line with Chinese road conditions and more in line with the driving habits of Chinese people. ClTC also tests a wider range of road conditions, including urban, suburban, and high-speed conditions, with a cycle time of 1800 seconds. However, the CLTC tested electric vehicle not only consumes 0 energy under parking conditions, but also can recover kinetic energy while driving, so the CLTC will have a longer range than the NEDC. For example, the mileage of Tesla's Model3 Performance version of the model has changed from the previous 605km to 675km with clTC standards, an increase of 70km compared with the previous one.

However, in the actual use process, although kinetic energy recovery can increase some endurance, but the ambient temperature and the maintenance of the air conditioning system on the mileage of the impact is also larger, this CLTC does not seem to be fully taken into account, so CLTC's working range display is higher than NEDC. It is precisely because of this advantage that many car companies have abandoned NEDC and come to the embrace of CLTC, but for consumers, CLTC's battery life data algorithm does need to continue to be improved to become a truly endurance evaluation standard that meets the national conditions.

EPA standards, the most stringent

In addition to the above several battery life standards, there is also a standard called the most stringent standard - EPA, the full name of the United States Environmental Protection Agency (United States Environmental Protection Agency) standard. The EPA standard includes four cycles of operating conditions: urban conditions, high-speed conditions, high-speed acceleration conditions and air conditioning conditions with relatively high energy consumption. Compared with the previous ones, the EPA's running method is complex, the speed changes more, the test time is longer, and it also supplements the full load of the air conditioner and the working conditions of high speed and rapid acceleration, and the test vehicle load is 200 kg, almost exceeding most of the human car habits, but the corresponding data is also the most referenced.

So how strict are the EPA conditions? For example, the BMW i4 released some time ago, the official data released is: the Cruising range under EPA conditions is about 482km, while the CRUIC standard is 625km. The difference between the two data is indeed a bit much, but in my experience with the car, if you can be sure to use the EPA condition as a reference to plan your charging, especially during long-distance driving.

At present, the accuracy ranking of the endurance standard should be EPA> WLTP> NEDC>CLTC, in terms of the current charging environment, the city can also be recharged in time for short-distance driving, but medium and long distance driving for electric vehicles is still somewhat "unfree", which requires us to have a certain prejudgment of the vehicle's endurance level, and make reasonable planning for the endurance level. Therefore, when choosing pure electric models, we must experience the real endurance level of the vehicle according to our own use, and do not be misled by the increasingly high mileage data.

GeekChoice original article