I want to spend a little time and share a little story with you. A few days ago, I suddenly got an idea. I immediately reported it to the boss in the company’s WeChat group. Within a few seconds, I got a simple and powerful reply from the boss: “Yes, it’s good”.
This brings up this new column: Why are the 100000 electric cars? I know what you will think at this time, but don’t get me wrong. This is not a popular science column.
Although I have been “training” in the field of new energy vehicles for more than two years, it is still a new field for me in terms of “electric” or “intelligent”. Therefore, I always have a learning and open mind, with the words “why” to understand and observe various new things in this field.
I believe that when we see more and more new brands, new cars, and new technology terms coming out, we will also have various questions. So I decided to formally put my understanding of these new technologies, my observation of the market, and my thinking on some issues into the new column “The 100000 Why of Electric Vehicles” from now on. I also hope it will help you better understand new energy vehicles.
Now, let’s talk about the body of electric cars. I want to ask you first: Have you noticed that electric cars are basically made wider than fuel cars of the same level?
As we all know, in the past, in order to better classify cars, in addition to cars/SUV/MPV and other categories, they will also be divided into small, compact, medium, medium and large categories according to their body length and wheelbase size.
Let me give a few examples first. For example, the Aian S Plus, which is classified as a compact car, has a body width of 1880 mm, which is not only far more than the same-level of Corolla but also 40 mm more than the higher level of Camry; For example, the extremely Krypton 001 and the long-wheelbase version of the Mercedes E class for medium and large vehicles. Although the vehicle length and wheelbase of the extremely Krypton 001 are shorter, the vehicle body width has reached 1999mm, which is 78mm more than that of the Mercedes S400L.
The most “outrageous” thing is that even being classified as a medium-sized car to the Weilai ET5, the body width exceeds the Benz S400L.
Do you know why electric cars are so wide?
Yes, the “culprit” is the battery under the electric car. You may often hear the word “energy density” of batteries. Still, you may not notice that the energy density of batteries is divided into two different dimensions, namely, weight energy density Wh/kg and volume energy density Wh/L.
In short, the lighter the battery is made, the greater the weight and energy density of the battery under the condition of constant capacity; The smaller and more compact the battery, the greater the volume energy density. Therefore, there are technical means such as wireless BMS systems, and CTP/CTC technology to improve energy density through physical means.
However, before the major breakthrough in electrochemical technology, the range of improving energy density by physical means is relatively limited. After all, in addition to considering the endurance, the safety of the battery pack itself is also very important. A very solid shell and some internal reinforcement are essential.
After all, considering the passing ability and sitting posture, the battery pack cannot be made too thick, so now all pure electric platforms should not only increase the wheelbase (longitudinal space) through the design of “four wheels and four corners”, but also make the body wider to increase the lateral space, so as to insert a larger battery.
The second main reason is to improve the safety of side impacts.
For fuel vehicles, there are only two reasons to make the body wider. One is to make the lateral space in the vehicle more spacious, and the other is to improve the stability of the vehicle during intense handling. Therefore, many supercar wheelbases are not long, but the body is very wide.
From all the crash safety tests in the past, it can be seen that there is no inevitable relationship between body width and crash safety.
However, electric vehicles are different. In case of a side impact, in addition to protecting the personnel in the vehicle, the battery pack should also be protected from deformation due to impact and causing a fire. Obviously, this requirement is higher than in the past.
From the structure of traditional fuel vehicles, we can see that in the past, we mainly relied on ultra-high strength steel on the side wall and B-pillar to resist the impact, but the sill beam and bottom crossbeam have not been strengthened too much.
However, it can be seen from the body design of electric vehicles of various brands that almost all-electric vehicles will significantly increase the rigidity and width of the side sill beams, and take the sill beams as a very important deformation and energy absorption area to resist the impact from the side. In order to further reduce the impact of the battery, 1-2 crossbeams will even be added at the bottom of the car body to strengthen the lateral anti-collision capability.
In extreme cases, if the sill beam is deformed, it is likely to hit the battery pack. Therefore, for the sake of safety, some manufacturers will also leave a certain space between the battery pack and the sill beam to ensure that the battery pack can be safe and not deformed in the event of a severe side impact.
So you say, if the car body is not made wider, how can you safely put in a larger battery pack?
Of course, the increase in the width of the car body also brings some problems. For example, the turning radius of the vehicle will become larger, which will be more obvious for large vehicles with a width of nearly 2 meters.
In order to solve this problem, some electric vehicles will solve it by increasing the steering angle of the front wheels, such as Volkswagen ID.4; Some will go further. For example, Porsche Taycan, Mercedes-Benz EQS/EQC, HiPhiX, Zhiji L7 and the next electric Macan all adopt the rear wheel steering system.
Another problem, of course, is the difficulty of parking, especially in some old indoor parking lots, or those mechanical three-dimensional garages. With the same width of parking space, it used to be easy to open the door when parking a Mercedes S-class, but now it may feel a little crowded when parking a very Krypton 001.
At this time, you will realize how important 360 panoramic images and a set of easy-to-use automatic parking systems are.
Did you find that electrification is not just about replacing the engine with an electric motor, but also affects other aspects? It may be necessary to make the car’s body so wide.
