Under the condition that the weight of the battery pack remains unchanged and the capacity increases, the cruising range of electric vehicles will increase all the way, from less than 200km at the earliest to 600-700km now, even if the cruising range is discounted, it is enough for most car owners to use it in one day.
But even so, in the face of many uncertain factors when charging, electric vehicles still can't achieve the charging efficiency of fuel vehicles, so the anxiety caused by charging is the crux rather than mileage anxiety.
In addition, it should be mentioned that with the increase of battery capacity, the charging time will be extended under the premise of the same charging power. Charging a charging pile with a speed of 60kW according to the national standard can fully charge the 60kWh battery 1-2 hours, and it often takes more than 3 hours to replace it with a battery pack with 100kWh.
In order to alleviate this phenomenon, Weilai launched its own power exchange service; Tesla, Weilai and Tucki have all introduced their own super fast charging systems, which can greatly shorten users' charging time.
In the past, we thought that changing electricity and overcharging were the favorite things of the new car-making forces, but in fact, among the traditional car-making forces, Porsche and Volkswagen are constantly exploring overcharging technology. In July this year, GAC Aian released the ultra-fast battery technology with the fastest charging speed at present, and with the appearance of Aion V Plus, this technology has officially entered the mass production stage.
Seeing this, I can't help but ask, is super fast charging really necessary? When watching the press conference, the words "highest" and "fastest" kept pounding our senses. So is the super fast charging technology really as magical as the manufacturer's propaganda? Can users really stop worrying about charging?
At the beginning of the article, we have basically understood the key to the rapid improvement of electric vehicle cruising range in recent years-the rapid improvement of battery energy density. However, under the existing battery chemistry system, the energy density of the battery has entered the bottleneck period, and it is difficult to improve the energy density of the battery without a breakthrough in chemical materials.
Compared with increasing the energy density of the battery, there is still room for improvement in technology, so when the capacity density of the battery reaches a certain bottleneck period, increasing the power density is naturally the main direction of some electric vehicle and battery manufacturers. All kinds of fast charging, overcharging and overcharging we saw were born.
In GAC Aian's view, in order to achieve more efficient charging, on the one hand, it is necessary to improve the power density of the battery pack, on the other hand, it is necessary to have charging piles that support greater voltage. The core of this super fast charging system carried by AION V Plus consists of super two-speed battery technology and supporting A480 super charging pile.
Compared with the voltage of the traditional battery pack of 300-600V, the battery pack voltage of AION V Plus can reach 880V V. With the A480 super charging pile, the maximum input voltage can reach 1000V, the maximum current can reach 500A, and the maximum charging power can reach 480kW. This Bitwatt Overfilled Pile (400kW), Tesla's V3 Overfilled Pile (250kW) and Weilai Overfilled Pile (120kW) are all higher. The official also confidently shouted the slogan of "charging for 5 minutes and battery life for 200km" to this super pile.
"A cup of coffee can be filled in time" and "charging is as convenient as refueling". Is super fast charging really as convenient as the manufacturer advertised? Let me add that the manufacturer won't tell you.
1.5 minutes to increase the endurance of 200km is conditional.
As we all know, the charging speed of any battery will slow down when it is almost full, which is directly related to the chemical characteristics of the battery, so charging for 5 minutes and battery life of 200km can not be satisfied in all cases. According to the introduction and measurement of Guangzhou Automobile Aian, the charging power of 480kW can only be achieved if the battery pack is connected to the super fast charging within the range of 30%-80%. When the battery pack is too low and too high, the input efficiency is not so high in order to protect the battery life. So don't take it for granted that if you charge for 5 minutes, you can increase the battery life by 200km, then if you charge for 5 minutes, you can increase the battery life by 400km in 10 minutes, which is impossible.
2. Power density (charge and discharge speed) and energy density cannot have both. ?
We mentioned in the last article that the improvement of battery energy density has entered a bottleneck period, so many manufacturers turn their attention to improving battery power density in order to obtain faster charging efficiency.
However, it should also be noted that the power density (charge and discharge speed) and energy density of the battery are contradictory in terms of indicators. In the figure, the abscissa is energy density and the ordinate is power density. We can see that the energy density and power density of the same battery are changing. On the one hand, it will inevitably affect the other. At present, the increase of battery power density will inevitably lose part of battery energy density, and how to make them reach the highest value as much as possible in a relatively balanced state is the biggest key.
In other words, under the same technical conditions, if you want to improve the charging speed (power density) of the battery, it will lead to the decrease of the energy density of the battery, and then reduce the capacity of the battery pack under the same weight. According to the super fast charging of AION V Plus, the battery can be charged 200km more in the range of 30%-80%, which is exactly half of the battery charge range. Assuming that the cruising range of electric vehicles in the range of 0-30% and 80- 100% is consistent with 30-80%.
3. Frequent use of super fast charging battery will affect the service life.
The battery life is an unavoidable problem in the new energy battery industry. No matter how carefully the battery is used, with the passage of time and the increase of battery cycle times, the capacity of the battery will inevitably decrease. The use of super fast charge is actually to exchange the life of the battery for the convenience of use, which has its special advantages in special use scenarios. Battery manufacturers can only use technological breakthroughs to continuously slow down the impact of ultra-fast charging on battery life.
The above picture shows the capacity attenuation of the same battery pack when it is charged slowly and quickly at room temperature. It can be seen that after 200 charge and discharge cycles, the capacity of the battery pack with slow charge decreased by about 14%, and that with fast charge decreased by about 37.5%. At this time, battery manufacturers can only use technological breakthroughs to continuously slow down the impact of ultra-fast charging on battery life, but this only slows down and cannot be completely eliminated.
4. Higher input power leads to a rapid increase in security risks. ?
As we all know, electric current generates heat. When we charge a mobile phone or computer, we will feel that the charger is warm, but the maximum current at this time will not exceed 10A. However, when vehicles use ultra-fast charging, it is considered that the power of 480kW needs the support of 500A current, and the increase of calorific value brought by the increase of current is not a simple multiple, but a square relationship: taking the current of 480A during ultra-fast charging as an example, the heat generated at this time is 900 times that when the current of 16A is slowly charged. This leads to a large amount of heat when ultra-fast charging and outputting the highest power, which poses a great challenge to the requirements of safety protection and cooling equipment.
5. The layout cost of ultra-fast charging is high.
At present, the power of ordinary fast charging piles in the State Grid is about 60kW, while high-power super-fast charging piles have higher requirements on site and electricity consumption, and the power load of super-charging piles on the grid will be greater, which also affects the construction and promotion of super-charging piles to some extent. If the number of ultra-fast cast-in-place piles is small and the coverage rate is not in place, it will easily lead to an increase in our pile sinking cost.
You know, Weilai, which started to build its own power exchange station system from 20 18, also took three years to complete the construction of 400 power exchange stations nationwide. Guangzhou Automobile Aian clearly stated that by 2025, 2,000 overcharging stations will be built in 300 cities across the country. Judging from the sales volume of 8 million electric vehicles nationwide by China Automobile Association in 2025, it is still unknown whether these 2,000 multi-charging stations can meet the needs of users at that time.
On the whole, the use of super fast charge can really solve the anxiety of energy supplement to a certain extent. However, in reality, it is still a common fact that electric vehicle users can't find the charging pile, the charging pile is damaged and can't be used, and it is said that the fast charging pile can't support fast charging. Therefore, the super fast charging technology is fragrant, depending on the actual car scene. It is the key to choose a cheaper price or a longer battery life according to your own car scene and needs. After all, what suits you is the best. If you like, please continue to pay attention to me, and more content will be brought later. Welcome to like and leave a message. (Some pictures are from the Internet)