What is the reason for the fire of the electric car?

Forfatter: Iflowpower – Fournisseur de centrales électriques portables

In just a few days, Tesla, Wei came, BYD and other electric vehicles have been fired, this "fire" burns red new energy car, the eyes of the whole industry are again focused on the security issues of new energy vehicles. Why is electric vehicles spontaneously ignite? What are the reasons for spontaneous combustion? Does the electric car really have fuel truck safety? Is there a way to solve the problem of the current electric vehicle? . with a series of questions, Gaiu has interviewed the Chinese Academy of Engineering Sun Fengchun Academician.

What are the main causes of electric vehicles? In Sun Fengchun, there are many reasons why electric cars spontaneous fire, but in general, mainly, battery problems. The problem of the battery is mainly reflected in the following aspects, one is the internal short circuit in the battery. For example, when the car is in vibration, the material is short-circuited after the material of the positive and negative electrode of the battery polar plate.

Since the internal short circuit is more difficult to control, it may be one of the reasons for self-ignition. Second, the battery connection is loose and external contact is poor. For example, Tesla is from 5,000 to 9,000 18650 batteries, or now this 21700 battery composed of battery packs, each battery can work, battery connection is mainly mainly welded or threaded, if During welding, there is a doubling or screw nut that is not tightened, which will cause loose when the vehicle produces vibration, which will cause the temperature rise of the battery system to exacerbate, so there will be fire.

The third is the battery over charge or over-discharge. In use, if the battery enters the lifecycle, due to inconsistency, this inconsistency, if it is inconsistent, if it is overcharge or over-discharge, the internal temperature of the internal resistance is increased, and it will generate spontaneous combustion. Phenomenon.

At the same time, because the temperature rises to self ignition has a process, it will be like this Tesla car, it is not charging and not in the process of driving, it will be placed in the area in the area will also catch fire. Why do Tasla will appear "Static Spontaneous Combustion"? In response to this problem, Sun Fengchun added to explain, before they have done the battery over the charging test, according to the specific situation of internal short circuits, generally not filled with electric horses, and may have to have a few hours after the battery is overcharged. Battery short circuit, especially the internal short circuit, its combustion or fire is very fast, due to the high pressure of Tesra high, it may have a flaming, the burning speed is very fast, will not catch fire like a fuel car Burning slowly.

At the same time, if it is a short circuit, from charging to self-ignition, if the car is driving, it will be slower. Due to the driving, there is a load current outside, which is equivalent to the outside to pick a resistor, and therefore, there is only a part of the current to circulate, and the other of the current is outside, but it can make the car normally open, so this is generally better than When driving, it is a bit of self-igniting or probability. Just like a gasoline car may appear static spontaneous combustion, all electric vehicles may also appear static spontaneous combustion in still state.

When the battery is short, it will induce the temperature of the battery. When it is raised to a certain temperature, it will happen to smoke, and then quickly expand. Compared to traditional fuel cars, the new energy car is not high, but because new energy cars are new things, they are more concerned, and they are more violent, so they will make the public consciousness believe that traditional fuel trucks ratio New energy car is safer.

There are also a lot of fuel vehicles, especially in the summer, the fuel-burning rate is still very high, it is not much lower than electric vehicles, but it is not so violent, but because the public has already happened to the gasoline car early, so it is affected Concerns relatively low. The harm of electric car spontaneous combustion is more harmful to fuel cars? The Teslai Library spontaneous combustion, the industry began to pass a sound "The harm of electric car spontaneous combustion is more harmful than the fuel car.".

For this point of view, Sun Fengchun said, whether it is a fuel car or an electric car, it will cause harm when spontaneous. At present, the fuel truck has been dropping emissions, which is to reduce the emissions of hazardous substances. Since the battery is considered to be a chemical product, the chemical reaction occurs when spherulating, and the harmful substances produced are more than the harmful substance.

In fact, both will have harmful substances, but only who is more and more problems. He believes that this problem should take data to talk, a set of quantities, according to its ingredients to infer the analysis, such as lithium iron phosphate or three-dimensional lithium battery, how much is the degree of harm according to its material, to carry out quantitative analysis, And can't be more violent because the battery is fierce, and the smoke generated is relatively large, and it is more pollution to the side. What new technologies are currently being developed? The battery industry has always pursued production safety and efficient batteries, and how to use the battery safer and efficient.

As we all know, in winter 40 degrees in winter, it is often encountered in the case of failing to enter electricity. This is due to the low temperature, the battery is not active. If it is forcibly charged, it will cause a substantial decrease in the battery life.

And the battery is also prone to fire phenomenon. For this problem, Sun Fengchun pointed out that if you can install a "switch of the battery work" on the battery, such as the "Delivery Battery" of the famous American Chinese battery expert Wang Chaoyang, that is, the battery is in the best state. Work, so you can guarantee the safety of the battery.

In addition, it is also possible to perform battery safety risks by battery management. In addition, in the case of low temperatures, the battery can be placed backwards, so that its security and life will be in a very good state. This is one of the technologies that they are studying.

Another technology is to develop solid-state batteries. In his view, the solid battery is a future development direction, which will greatly improve the safety of the battery. The relationship between life and security is currently, in order to increase the endless mileage, the new energy car companies have risen to the application of high-energy density batteries, and the emerging power headed by Tesla is more energy density.

Listed as a non-two choice for endless mileage, but the endless mileage improved the seeds of battery safety hazards. In fact, there is a certain correlation between life and security, the higher the life, the more security risks may be relatively large. In the view of Sun Fengchun, the safety problem of electric vehicle is mainly caused by the battery.

The more battery is used, and the safety risks will be larger. Therefore, let the company do the battery to ensure the safety, so that the solder joint will be less, and there will be some problems internally. Therefore, domestic Ningde Times, BYD and other large enterprises, most of them rarely use cylindrical batteries, when they do the capacity of cylindrical batteries, if there is a short circuit inside, its pressure will be particularly high, it is easy to combustion.

In addition, since the battery is too cost, when the subsidy is zero, Sun Fengchun believes that the battery life should be used in accordance with user needs, and the battery will be configured according to the user mileage mode. At the same time, there is no doubt that with the improvement of battery technology, pursuing high security and high energy density is a theme of battery eternal development. In addition, Sun Fengchun believes that rapid replacement battery is also a method of improving battery safety.

If there is a problem with the battery, you can realize a one-button release. By pressing a key to quickly freely free, it will not be burned along the battery. Generally, the passenger car will change the battery in two minutes.

The bus or logistics vehicle may take three minutes to five minutes to finish it. Very convenient. If possible, you don't need to install so many batteries, so security will naturally improve.

For new energy cars, how to do safety protection, Sun Fengchun believes that car enterprises should be aware of every step, everything, everything, it is very serious from design to test. If there is a problem, go to solve the problem, carefully, analyze, analyze and summarize. Since there will be some responding characteristics before the battery spikes, each car company should make monitoring through its own regulatory platform, find the problem to feed back the problem in time, which will significantly reduce the incidence of accidents.

Despite the current new energy vehicles now spread, 3 million vehicles in the country, which is very small compared to the entire car of China, and the technology development of the car is a step-by-step process. With the complete slope of new energy car subsidies, there will be some companies to face out the out-of-life. With the continuous improvement of new energy automobile technology, the gradual improvement of various policies and regulations, and the increase in national supervision, new energy vehicles will be more secure.

Gaiu.