Electric car prospective car owners must know: these 8 big problems need to be clear

In the face of the current tens of millions of electric cars, how much of our money is spent on car purchases, and how much is used to buy batteries? The battery is the heart of the electric car. Its quality will directly affect our normal travel. Compared with the fuel car, the biggest problem is the safety of the battery and control circuit. Therefore, it is a top priority for its maintenance work. For the electric car that moves hundreds of thousands of dollars, you must first understand the problem of its core components (battery), and understand it clearly to buy it.

Life mileage

Lithium-ion batteries are relatively sensitive to temperature, and the temperature can be said to be the killer of lithium batteries for electric vehicles. Generally, the operating temperature range of a lithium battery is concentrated between -20 ° C and 200 ° C. However, the temperature sensitivity of lithium batteries of different material types is also different.

Among them, the lithium iron phosphate battery, which is currently the most widely used in China, has better high temperature performance, but lacks tolerance for low temperature. For some better quality products, only 80% of the electrical energy is released at -20 °C, and below -40 °C, the battery is often "frozen" and irreversible damage to the internal material crystallizes. Although some manufacturers have developed lithium iron phosphate batteries doped with manganese or olivine crystal structure, they can cope with lower temperatures, but they will also have more discounts in power and cruising range, and higher costs.

Lithium batteries of ternary materials and lithium cobalt oxide materials are sensitive to high temperatures in addition to low temperature (below -40 ° C) discharge decay. When the operating temperature exceeds 220 ° C, it will cause irreversible damage to the battery structure.

In the low temperature environment, it is also shown that there is a long cruising range before starting, and the value is greatly reduced immediately during driving, which is often caused by the low actual battery output of the battery. In a high-temperature environment or continuous driving for a long time, if the battery cruising range is sharply reduced or the current is interrupted, there may be a problem that some of the batteries have heat dissipation, and the protection system turns off some of the batteries with excessive temperature. Therefore, in use, consumers should pay attention to the use environment of electric vehicles, but also pay attention to keep the front grille clean, so as not to cause poor heat dissipation.

2. Battery spontaneous combustion

When the outdoor temperature is 38 ° C, the surface temperature is estimated to be close to 60 ° C, which means that the season when the vehicle is most likely to break down is coming. Electric cars are inherently safe. For the self-ignition accident of lithium batteries that people are worried about, with the improvement of battery technology and the improvement of technology, it has rarely occurred in recent years.

Even if it happens, it is the extreme situation that occurs when the vehicle has suffered a serious traffic accident, resulting in the disintegration of the vehicle and the failure of the battery safety protection system. Moreover, the spontaneous combustion of the lithium battery is also related to the battery material used. The lithium batteries of our mobile phones, charging treasures and electric bicycles usually use lithium batteries of ternary materials or lithium cobalt oxide materials. These batteries are affected by the thermal instability of the materials, and when they are subjected to high temperatures, they emit flammable substances. This causes the battery to ignite and even explode. For the lithium iron phosphate battery widely used in China, the thermal stability is good, and no combustible material is generated even under the condition of overheating and impact. Therefore, there is no need to worry about the self-ignition of lithium batteries in electric vehicles.

3. Fast and slow charging

The charging mode of electric vehicles includes slow charging and fast charging.

For more than 20 kWh of battery energy, it takes about 8 hours to use the ordinary power supply from the battery to fully charge the battery, which is obtained under the test conditions. It is impossible to use zero battery power in daily driving, and the lowest is the remaining 10% to 20%. In other words, it can be fully charged in about 6 hours in normal use.

However, for most car manufacturers, it is not a good idea to use this fast charging method too much. Because shortening the charging time means that according to the law of conservation of energy, it is necessary to increase the charging current and voltage, and charging with a large current and voltage will cause a certain voltage shock and overheating danger to the battery, resulting in irreversible battery structure. damage. Greatly affect the cycle life of the battery.

In slow charging, the cycle life of the battery can usually reach more than 2000 times. In the case of fast charging, the cycle life will be quickly shortened to less than a thousand times or even lower. Fast charging is not only an increase in electricity bills, but also a significant increase in battery breakage costs. For most car owners who are pursuing economic use, fast charging is better used temporarily in emergency situations.

4. Insurance

As a key component of electric vehicles, batteries account for roughly 30% of the total price. For electric vehicles, it is difficult for insurance companies to introduce separate insurance programs for battery damage. Even in the case of vehicle damage insurance, compensation for battery damage is not included. The main reason why batteries are difficult to insure is that insurance companies are difficult to judge the valuation and damage of power lithium battery products used in electric vehicles, which makes it difficult for insurance companies to predict risks and set premiums.

Specifically, first, the composition of a lithium battery of an electric vehicle is complicated. Since the lithium battery system is usually composed of a positive electrode material, an electrolyte, a negative electrode material, a protective case, an electrode lead, and a battery management chip. These components are typically millimeter, micron-sized devices. Among them, problems in each part may cause damage to the battery. As an ordinary electric vehicle, the battery pack usually contains hundreds of such single cells.

The use of ambient temperature is too low and too high can cause the lithium battery to be denatured from the internal material, causing the entire battery to be damaged or the performance is greatly reduced. Too bumpy roads or car bottoms can also cause the battery to suffer from violent bumps and internal structural damage. Too much humidity or wading can cause water in the battery or corrosion of components.

The most deadly thing is that the battery damage caused by these factors often cannot be attacked at that time, but gradually accumulates and gradually deteriorates during use. This makes it difficult for insurance companies to determine the immediate risk of battery damage. Finally, there are many types of lithium batteries used in electric vehicles, and the production of power lithium batteries lacks national uniform standards. Even the same model, the same manufacturer's car and battery are inconsistent.

Battery materials vary widely, battery quality is uneven, and standards are missing, making it difficult for insurance companies to determine the actual value of batteries and maintenance costs. It is even more difficult to distinguish between damage caused by product quality or accidental damage caused by vehicle owners.

At present, due to the lack of lithium battery technology, industry level and corresponding judgment standards, the damage determination and insurance for lithium batteries of electric vehicles is still a problem.

5. Warranty

In response to consumer concerns about the quality and service life of electric vehicle batteries, various electric vehicle manufacturers have introduced battery manufacturer warranty commitments. Some promised 100,000 kilometers in 5 years, the battery quality problems were replaced free of charge, and some promised 150,000 kilometers in 6 years. BYD even proposed a permanent free replacement of battery quality problems.

In fact, we found that on the one hand, the larger the scale and the stronger technology, the longer the mileage and the age of the battery warranty. On the other hand, we find that there is still a lack of detail in these commitments.

The first is how to determine that the battery has been quality problems, there is no clear standard here. Intuitively, if the battery's cruising range is greatly reduced in the short term, or the battery power suddenly decreases during driving, it can be used as evidence that the battery has already had problems. However, these intuitive phenomena lack corresponding technical data as a criterion.

In addition, how to identify the battery quality problem, or the consumer's improper use of the fault, is also a problem.

If, when the battery fails, you find the manufacturer's request to honor the warranty and replace the battery for free, the manufacturer replies to you. In your vehicle insurance, there was a vehicle wading or bottoming repair two years ago. If you use a malfunction caused by improper use, then who will judge as a third party?

Therefore, when consumers purchase electric vehicles, they need to implement specific invitations with the manufacturers for battery warranty, and they can also indicate the specific identification methods for quality problems through supplementary forms. At the same time, it is also hoped that auto manufacturers will try their best to make the warranty commitments more detailed, so as to dispel consumer concerns.

6. Price

In the face of the current tens of millions of electric cars, how much of our money is spent on car purchases, and how much is used to buy batteries? According to the average estimate, the battery accounts for about 30% of the total vehicle, that is to say, a pure electric vehicle of 300,000 yuan, the battery cost is about 100,000 yuan.

However, this is only an average value. For auto companies with different technical capabilities, production scales, and different product positioning and pricing strategies, this value is quite different.

So how do we measure how many orders we bought for new energy? Or is it a gimmick for manufacturers to use new energy vehicles?

Among them, as a consumer can be compared with the same model, the same level of the traditional fuel car and electric car.

A=(electric vehicle sales price-fuel vehicle sales price)/battery energy marked by electric vehicle manufacturers

A can be roughly equal to the average energy application cost of the unit battery. In the case of the same class, the smaller the value of A, the less we spend on new energy for electric vehicles. Conversely, the higher the value of A, the higher the cost of the company's new energy concept. In this regard, consumers can calculate their own and make their eyes clear.

7. Electric car battery recycling is easier

Regarding the recycling of electric vehicle batteries, there is a view that China's recycling system still needs to be improved, especially in terms of technology, standards and processes. Compared with the recycling of small batteries, the battery of an electric vehicle is easier. Because it belongs to a large battery pack, it will consume much less manpower, material resources and financial resources than a small battery. At the same time, the recovered battery can also be used for energy storage, which has a huge market space. For the energy storage system, the replaced battery still has a large use value, and establishing a power battery cascade utilization and recycling management system is a feasible option.

China Automotive Technology and Research Center predicts that by 2015, the cumulative amount of domestic power batteries will be about 20,000-4,000 tons. By 2020, the cumulative scrap of China's electric vehicle power batteries will reach 120,000-170,000 tons.

8. Protection battery principle

In general, the normal service life of a car battery is 2-3 years; if the "three noes" principle is adhered to during the daily use of the car, the service life of the battery can be extended.

First of all, in the flameout state, the in-vehicle electrical equipment cannot be used for a long time. Some car owners after the flameout or listening to the radio or watching the DVD, doing so, although it can save fuel, but will deeply damage the battery, some are not worth the candle.

Secondly, the external power supply device is not used in the flameout state. Nowadays, many car owners will always have a car vacuum cleaner, a portable air pump, etc. It should be reminded that these external power supply devices should not be used when the vehicle is turned off. Because the power of these devices is relatively large, it will quickly consume the stored electricity in the car battery, affecting the normal start of the vehicle.

Again, don't forget to turn off the headlights after parking. Mr. Wang, the owner of the car, went to Hangzhou for self-driving tour. After parking the warehouse, he forgot to turn off the headlights. The next day, the vehicle was directly in the armpit. The rescuers were on the scene and gave him a battery maintenance class. Unfortunately, after a month, Mr. Wang once again forgot to turn off the lights, causing the car computer to lock up and the system data to be lost. Finally, the car was towed to the 4S shop.