The dawn of breaking the anxiety of endurance may be at hand.
Author: Wu Jingtao
At this stage, battery life anxiety is like an insurmountable mountain, blocking the way for many consumers to choose pure electric models. Therefore, for a number of car brands, who can take the lead in crossing this mountain can occupy the high ground of technology and public opinion.
If there is a large enough market demand, there is naturally a strong enough impetus for innovation. Since the end of last year, some car brands have successively launched their own ultra-long endurance models to showcase their technical achievements. For example, GAC Aeon's AION LX PLUS has taken the lead in launching a mass production model with a range of 1,000km (CLTC conditions) in China.
Last week, Mercedes-Benz announced that its electric concept car EQXX has run an exciting 1000KM+ mileage in a real road environment.
Ultra-long endurance has become the mainstream solution to solve the anxiety of electric vehicle endurance. And "thousand mile endurance" has gradually become a punch card challenge for electric vehicles to prove their "durability". The so-called one minute on stage, ten years offstage. To break the bottleneck of endurance anxiety, how much effort do engineers need to put into vehicle design? In today's article, we will take Mercedes-Benz's EQXX concept car as an example to discuss this problem with you.
01
Reduces drag and is silky smooth
Just a brief review of the physics knowledge of junior high school, we can know that the resistance of the car in driving is: rolling resistance, acceleration resistance, slope resistance and air resistance. Of these four resistances, air resistance and rolling resistance are present in any driving situation. Therefore, in order to reduce driving resistance, it is necessary to spend great efforts on these two points to optimize.
First of all, in terms of air resistance, it is not difficult to see the shape of this EQXX, and it is not difficult to find that there is a big difference from the electric vehicle models currently on sale. When I first saw the shape of this car, I thought it was a car that jumped out of gta games to reality.
In fact, this EQXX is the flagship electric model of Mercedes-Benz designed by the Formula 1 team. The design is derived from the aerodynamic concept car Concept IAA released by Mercedes-Benz in 2015.
The design has three aerodynamic highlights, one is a very low windward area of only 2.12 square meters. (Windward area is even smaller than Smart)
The second is the narrower rear wheelbase than the front wheel, so that the body is an inverted triangle of "water droplet" streamline, which is more in line with the design requirements of reducing air resistance;
The third is equipped with an active rear diffuser, which will automatically open the optimized air flow when the speed reaches 60km/h, thereby reducing the wind resistance coefficient when driving at high speed.
After up to 8 million CPU hours of simulation optimization, the final result is that the EQXX has a drag coefficient as low as Cd 0.17. If you don't have a specific concept of this value, then to put it in a concise and clear way, this value directly breaks Mercedes-Benz's own record. The previous record holder was the Mercedes-Benz EQS with Cd 0.2.
Incidentally, EQXX did not use cameras instead of mirrors to further reduce the drag coefficient. In the case of using traditional lens-type rearview mirrors, EQXX can still achieve such excellent wind resistance results, which shows the aerodynamic achievements of traditional luxury brands such as Mercedes-Benz.
Rolling resistance is another key direction that can reduce driving resistance. In the optimization of this point, the technical route taken by each brand is highly the same. After all, only the tires come into direct contact with the ground, creating rolling resistance. Therefore, replacing energy-saving oriented tires with lower rolling resistance has become a common practice in every household.
At EQXX, Mercedes-Benz and Bridgestone tailored a set of low-roll-drag tires from the Tunza Eco series. It adopts the narrow tire width and large diameter size design commonly used in electric models, and the tire diameter of 20 inches is only 185 mm.
Combined with the fully enclosed wheel shape and the air breather wind curtain composed of ventilation holes on the front surround sides and fenders, it reduces the turbulence caused by tire rolling. A set of combination punches down, so that EQXX's tire roll resistance coefficient is only 4.7.
In the optimization of driving resistance, Mercedes-Benz uses its strong technical accumulation in aerodynamic design and in-depth cooperation with suppliers to create a "textbook" low driving resistance parameter for EQXX. This laid a solid foundation for its goal of achieving a long range.
02
Total weight loss
"Wanting to let the horse run, but not letting the horse eat grass" has been a problem that human beings have been trying to make "better solutions" since ancient times. In the matter of electric vehicle endurance, how to better solve this problem is also critical.
To increase battery life, most people's first reaction is to increase the battery capacity. After all, when we buy an electric model, the mileage of the model is often positively correlated with the capacity of the battery. The larger the battery capacity, the longer the range is already an inherent perception of most consumers.
But increasing the battery life often means increasing the volume and weight of the battery. Imagine, under the premise of the same explosiveness and endurance, under normal circumstances, a fat man and a thin man, who can run faster and farther? The answer is clearly the latter, and Mercedes-Benz also wants the EQXX to be the latter.
Therefore, Mercedes-Benz is equipped with a new battery pack on the EQXX, and under the premise that the overseas version of the EQS battery capacity is about close, the battery pack volume of the EQXX is 50% smaller than the EQS battery pack, the weight is reduced by 30%, and the weight of the 100kWh battery pack is controlled at 495KG, which truly does not increase the weight.
The reason why such a brilliant improvement can be achieved is due to the increase in energy density of the new battery pack. The new battery pack has an energy density of nearly 400WH/L and an operating voltage increase of more than 900V, which is also the first application of 900V technology.
The addition and subtraction of the photocell pack is not all, and the body structure is also the direction that can be used to make lightweight articles. On the body of the EQXX, Mercedes-Benz uses lightweight composite materials and integrated bionic castings to reduce the weight of the body. The combination of the two reduces the weight of the EQXX body structure by 20%, so that the model equipped with a 100kWh battery pack weighs only 1755KG.
03
Open source throttling
With the two solid foundations of low driving resistance and lightweight, whether a fixed amount of energy can be used efficiently becomes the ultimate decisive key.
The first is power consumption, the EQXX's powertrain consists of electric motors, transmissions and power electronics, which mercedes-benz developed in collaboration with F1 experts from High Performance PowerTrain GmbH (HPP) and is capable of transferring up to 95% of the battery energy directly to the wheels, reducing the loss of the drivetrain by 44%.
Together with the intelligent energy consumption assistant, efficient driving recommendations based on the vehicle condition and external environment. The EQXX achieved an ultra-low energy consumption performance of 8.7 kW/100 km under the test conditions of a maximum speed of 140 km/h and an average speed of 87.4 km/h. (This also includes 14 km uphill) After a full 1008 km journey, the vehicle can still travel about 140 km.
In terms of throttling, EQXX's energy consumption performance is amazing. In terms of open source, Mercedes-Benz is not sloppy in the slightest. In addition to the conventional ones, 117 solar cells were installed on the roof to power the navigation and other electronic equipment on the car, adding about 2% of the vehicle's cruising range. Mercedes-Benz engineers also took the trouble to equip the EQXX with multi-source heat pumps.
Not only can heat be absorbed from the surrounding environment, but also from conventional systems, so that the vehicle does not produce waste heat to the greatest extent. At the same time, the heat dissipation plate installed on the bottom plate of the vehicle can use the air flow to evenly cool the transmission system, reduce the energy consumption increased by active cooling, and add an additional cruising range of about 20 kilometers.
It is no exaggeration to say that EQXX's "iron rooster" general throttling and "clever and bold" open source have played a decisive role in the realization of its ultra-long endurance.
Write at the end
After Mercedes-Benz announced the test results of EQXX, the mainstream argument on the Internet can be roughly divided into two categories. The first category is the highly recognized EQXX's outstanding performance in actual road tests, which can run more than 1000 kilometers on a single charge. It is believed that this shows the deep technical foundation of Mercedes-Benz as a traditional car brand. It proves that traditional car companies can also hand over eye-catching excellent works in the field of new energy.
Another argument is that no matter how well tested the test is, it should be clear that the EQXX is still just a concept model. Combined with the energy consumption performance of the previous EQS, it is too early to conclude whether the final mass production model can make such an achievement.
In my opinion, I will be optimistic about EQXX's performance. Looking at the problem from the perspective of development, although the current EQXX is still nominally in the state of the concept car. However, in this actual road test, we can find that in order to achieve the set goal of long mileage, it has a complete set of systematic design and highly perfect calibration.
From reducing driving resistance, lightweighting the body, increasing energy density, and "open source throttling" of energy. As we saw on EQXX, Mercedes-Benz gave an almost "textbook" model design that achieves ultra-long-distance cruising range and eliminates endurance anxiety.
Whether Mercedes-Benz is ultimately going to mass-produce the EQXX or exist as a technically proven model. This test result of EQXX undoubtedly gives all people who pay attention to the development of electric vehicles a dose of "cardiotonic agent".
Although at present, the bottleneck of battery life still greatly weakens consumers' confidence in purchasing pure electric models and the user experience of electric vehicle users. But in order to solve this bottleneck, the technical research has never stopped, and from models such as the EQXX, we seem to be able to vaguely see that the dawn of hope is close at hand.
Today's topic
How long will it take for the battery life anxiety of electric vehicles to be eliminated?
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