[Aika Auto Aika Research Institute Original]
For the endurance problem of pure electric vehicle models, many car owners can't help but complain, obviously the nominal mileage, but their actual driving is greatly discounted. But at the same time, many car owners said that their pure electric vehicle model endurance is more accurate, basically can run to the manufacturer's label of endurance. Then it is strange, the same is a pure electric model, so why is the gap so large. Because regardless of driving habits and the environment in which the car is used, the difference in test standards will also affect the real endurance of pure electric models. At present, the mainstream test standards are mainly 3 kinds, NEDC, WLTP and CLTC, so what is the difference between these three test standards, and for our consumers, which test standard has the most reference significance? Let's take a closer look at it today.
NEDC: The longest used in China and the widest range
NeDC's full name is New European Driving Cycle, that is, "new European driving cycle test", in simple terms, NEDC is the European endurance test standard, in the early days, the Ministry of Industry and Information Technology in the comprehensive mileage of pure electric vehicles to test the use of NEDC test standards. This standard is mainly used in Europe, China, Australia and other countries. This set of test standards was introduced in 1980, and the last update was in 1997.
NEDC's test criteria are divided into two parts, namely Urban Driving Conditions (City) and Suburban Driving Conditions (Highway). The urban driving condition consists of four ECE-15 (urban driving cycle) cycle units, which end in a theoretical distance of 994.03 meters in 195 seconds, and in this 195 seconds, the test vehicle accelerates from stationary to 10km/h, 30km/h, 50km/h on the bench according to the specified time and acceleration, decelerates or brakes at a uniform speed for a period of time, and then this process is repeated four times, a total of 780 seconds, with an average speed of 18.35 km/h. Then began the test of suburban driving conditions, the car simulated a section of acceleration from stationary to 60km/h, after which even acceleration and deceleration, respectively, from 50km/h, 60km/h, 100km/h and 120km/h uniform driving conditions for a period of time, a total of 400s, the average speed of 62.6km/h, after a cycle to calculate the suburban / high-speed energy consumption.
WLTP: The most mainstream test standard in Europe
The full name of WLTP is "World Light Vehicle Test Procedure", which was jointly formulated by Japan, the United States, the European Union, etc., and its final version was officially compiled in 2015. Compared with the old NEDC test, the WLTC test conditions are significantly more complex. First of all, the WLTC formulated three sets of test curves of Class 1, 2 and 3 according to the power-to-weight ratio of different vehicles. The electric passenger cars we were able to buy were tested according to the Class 3 standard with the largest power-to-weight ratio.
Compared with the NEDC standard, the simulation scenario of the WLTP standard is more complex, and is divided into four working conditions: low speed, medium speed, high speed and ultra-high speed, and the maximum speed is 56.5km/h, 76.6km/h, 97.4km/h, and 131.3km/h, respectively. The average speed is between 18.9km/h and 92km/h, and the total test time is 1800s. Each cycle not only travels longer distances, but also takes longer test times, and the acceleration and deceleration process during the test is also more random.
In addition to the difference in speed and scene, the WLTP standard also takes into account the rolling resistance, gear, and weight (cargo, passengers) of the vehicle, which makes the new regulation closer to the reality.
CLTC: More nationally appropriate
Whether it is NEDC or WLTP, both test methods are based on the european user car habits derived from the test method. Because our domestic car habits are relatively close to Europe, the domestic test method has always been a reference to the European WLTP standard. However, foreign test standards are still different from the domestic use environment, so in this context, CLTC also came into being.
Before talking about CLTC, we have to understand CATC, CATC is the abbreviation of ChinaAutomotiveTest Cycle, Chinese called China's car driving conditions. CATC consists of two parts, namely China Light Vehicle Driving Conditions (CLTC) and China Heavy Commercial Vehicle Driving Conditions (CHTC).
The CATC standard integrates the painstaking efforts of more than 70 research groups and more than 1,000 researchers. Based on the establishment of 3832 vehicle collection fleets in 41 representative cities, covering traditional passenger cars, light commercial vehicles and new energy vehicles, they collected about 32.78 million kilometers of vehicle movement characteristics, power characteristics and environmental characteristics data. The collected roads cover urban areas, suburbs, main roads, expressways and highways, and the time also covers seasons, weekdays, holidays, peak hours and peak hours. The result was a standard test condition that was closer to the habits of Chinese drivers.
CLTC includes urban, suburban and high-speed conditions, with a cumulative mileage of 14.48km, a maximum speed of 114km/h, and an average speed of 28.96km/h, removing the ultra-high-speed working conditions in the WLTP cycle, but the total cycle time is still consistent with the WLTP, which is 1800 seconds. Compared with the WLTP cycle, the average speed of CLTC urban, suburban and high-speed conditions has decreased to varying degrees, and the acceleration and deceleration processes during the test are also more gentle, but the peak deceleration is higher than that of WLTP, and the deceleration time is longer.
Compared with Europe, domestic traffic is more congested and the road conditions are more complex, so the CLTC test standard is slightly different from the WLTP. During the 30-minute bench test time, about 40 percent of the vehicle was accelerated, about 35.5 percent of the time was in a deceleration state, about 2 percent of the time was cruising, and the rest of the time was in a parked state. Compared with WLTP and NEDC, CLTC test standards occupy the least amount of time in the high-speed part, and the maximum speed and average speed are the lowest, mainly because it matches the current high-speed regulatory requirements and the big data collected by traffic GIS.
NEDC/WLTP/CLTC test standard
After introducing these three test standards, let's take a specific look at what advantages and disadvantages are between them, first of all, THE NEDC test standard. The biggest advantage of this set of standards is that the test time is short, and the test standard is simple and easy to operate. However, in contrast, neDC standard tests are too idealistic, such as in the 195-second urban driving cycle, mechanized repeated start-up, acceleration, uniform speed, deceleration and parking and other stages, but in real life these tests are almost not repeatable and comparable. Another example is that there is no auxiliary equipment such as air conditioning or heating windows during the test cycle. Therefore, there will always be a big difference between the data obtained using the NEDC test standard and the actual situation.
Since there is a big difference between the test results and the actual situation, why not replace it? There's a reason for that. In the early days, China also used NEDC as a test standard, first of all, there was no other standard available at that time, and secondly, after having a more stringent test standard, the new standard needed time to be gradually optimized, and even if the test standard was replaced, it also needed a certain period of transition.
At the same time, it is precisely because the NEDC test standard is not very reliable, and the measured data is more beautiful, so domestic manufacturers will also prefer the NEDC test standard. After all, in the three sets of standards, NEDC can measure a longer cruising range, so that manufacturers have more bragging capital when promoting. So to sum up: NEDC, manufacturers like it, but consumers don't like it. At present, there are many models that are still using the NEDC test standard, such as the krypton 001 that has exploded, most of BYD's models, and the Volkswagen ID. series are using this test standard.
As for the WLTP test standard, compared with THECD, its test standard is more complex and more stringent, so the advantages are also obvious, that is, the test data is more accurate, and now a large number of car companies have abandoned the NEDC and used the WLTP test standard. For example, Mercedes-Benz's EQ series, BMW's iX series and other models have used WLTP test standards.
However, although WLTP is more stringent than NEDC, the data obtained is more realistic and has more reference significance for consumers. However, WLTP is still a test standard for more European habits after all, so compared with the more complex driving environment in China, WLTP will also be somewhat "unsatisfactory" in China.
Finally, there is CLTC, the biggest advantage of this set of test standards is that it is in line with the actual car environment in China, after all, all the data comes from the actual collection and analysis of big data. And for pure electric vehicle models, CLTC also deletes the isazoelectric method, increases the experiment of turning on air conditioning at high and low temperatures (high temperature 30±2 °C, low temperature -7±3 °C), and evaluates the energy consumption of electric vehicles more objectively and realistically. Therefore, in contrast, this set of test standards is more referenced for consumers.
CLTC test standards have been implemented on October 1, 2021, so the mileage of existing models is based on CLTC as a test standard, such as the recently listed GAC AION LX Plus, its top model mileage exceeds 1000km, which is obtained through CLTC, so the data given by GAC Aean officially, I am personally more convincing. By 2025, all new energy vehicles will use the CLTC standard to determine the mileage, at which time we will also be able to obtain more authentic and credible vehicle endurance information.
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