Will fast charging and overcharging necessarily damage the battery?
Recently, Mr. Zhong, a new car owner in Guangzhou, told a reporter from Yangcheng Evening News that he is worried that fast charging and overcharging will seriously damage the battery life, and he will only choose slow charging in the future. The reporter visited the market and found that there are still many car owners who have such concerns. In addition, there are rumors in the market that "new cars need to be fully charged before charging".
Clarifying facts and cracking rumors is beneficial for improving consumer quality, optimizing the consumer environment, and promoting the production and development of related enterprises. In addition, regarding the sustainable development of new energy vehicle batteries, charging stations, and other aspects, at this year's National People's Congress and Chinese People's Political Consultative Conference sessions, representatives from the automotive industry, as well as members of the Chinese People's Congress and the Chinese People's Political Consultative Conference, gave suggestions and discussed how to start from "electricity" and help the high-quality development of the new energy vehicle industry.
Should the new car be fully charged for the first time
Rumors still exist in the new energy vehicle consumer market that new cars need to be charged from zero to 100 before running out of battery. The emergence of this rumor may be traced back to the era of non smartphones.
At that time, mobile phones used nickel chromium batteries or nickel hydrogen rechargeable batteries, and consumers were accustomed to using up the battery before fully charging it for the first time. The widely circulated belief at the time was that this type of battery had a certain "memory effect". If the phone was charged before it was fully charged, the contents of the battery would crystallize, causing the battery to "mistakenly think" that it was no longer charged. Over time, the battery capacity would decrease until it could no longer store electricity.
Up to now, batteries used in new energy vehicles are all chemical batteries. Common types of power batteries include lead-acid, lithium titanate, lithium cobalt oxide, lithium iron phosphate, nickel cobalt manganese, and nickel cobalt aluminum. Regardless of common electronic devices or new energy vehicles, lithium-ion batteries are currently the mainstream choice. Lithium compounds are used as electrode materials, and graphite is used as negative electrode materials.
According to the WeChat official account of the Institute of Physics of the Chinese Academy of Sciences, among all the commercially available batteries, the energy density (electric energy stored per unit volume) and specific energy (electric energy stored per unit mass) of lithium ion batteries are the highest. At the same time, the cycle life of lithium ion batteries is very long. The cycle life of excellent ternary material batteries can reach more than 3000 times, and that of lithium iron phosphate batteries can reach tens of thousands of times. If you charge them once a day, you can use them for 8 years and 27 years respectively. In addition, lithium-ion batteries have the advantages of light weight, low pollution, and no "memory effect". That is to say, new energy vehicles using such batteries do not need to run out of battery first and then fully charge them.
At present, new energy vehicles can travel about 100 to 200 kilometers when fully charged, and can be used for a day to a week before being recharged. According to some 4S store staff, the first charge can be fully charged, and it is better to start charging when there is about 20% remaining battery. The most important thing is that shallow charging and discharging are safer, and attention should be paid to avoiding overcharging, over discharging, and under charging. The color of the charger indicator light should be used to determine whether it can be charged. Therefore, it is generally recommended that consumers choose to charge during the day in order to control the charging time.
Will fast charging and overcharging batteries definitely shorten their lifespan
With the continuous increase in the production, sales, and ownership of new energy vehicles, the high vehicle to vehicle ratio has led to difficulties in waiting for a pile and difficulties in obtaining a pile during holidays. Driven by "charging anxiety", the era of overcharging of new energy vehicles has arrived, and China is accelerating the construction of charging and swapping facilities. In 2022, the number of charging stations in China has increased by nearly 100% year-on-year. Accompanied by this is another level of anxiety: fast charging and overcharging can lead to battery life loss.
The so-called slow charging refers to AC charging, which usually takes 6 to 8 hours to fully charge the battery. Fast charging and overcharging refer to high-power DC charging, which can charge up to 80% or more in just half an hour or even less. A charging rate exceeding 1C is generally considered fast charging. 1C refers to the full capacity of a battery, and 1C charging means it takes 1 hour to fully charge the battery.
The main factors closely related to battery health are thermal management and BMS (Battery Management System).
The book "Automotive Big Data Application Research Report (2021)" mentions that nine common factors affecting battery health include: current battery capacity, battery internal resistance, charge and discharge depth, charge and discharge rate, self discharge rate, overcharging and over discharging, number of cycles, charge and discharge current, and temperature. Among them, in terms of charging and discharging rates, when charging at high rates, the temperature of the battery may rise too quickly, adding difficulty to thermal management and leading to a deterioration of battery health.
BMS is known as the "protector" of batteries, which can detect and analyze the battery status, avoid over discharge, and extend the battery's service life.
The use of safe and reliable thermal management systems, BMS, etc. can effectively protect battery health. For example, the 2021 annual report shows that CATL has owned and is currently applying for a total of 10222 domestic and foreign patents, including modules, BMS, thermal management, and battery systems for thermal safety. In November 2022, Ningde Times applied for a patent for "Vehicle Thermal Management System and Vehicles", which can improve battery temperature and endurance. By using the products and services provided by these large manufacturers and cultivating good charging habits, the normal fast charging and overcharging can relatively ignore the battery loss.
Boost the battery industry to break through charging bottlenecks
China is the world's largest market for new energy vehicles. Power batteries are considered the core of new energy vehicles and a key link in the industry chain, and the rapid growth of charging infrastructure effectively supports the rapid development of new energy vehicles. Next, how to continuously promote the healthy development of the power battery industry and optimize the layout of the charging network is an important topic to be solved.
In recent years, the domestic battery energy storage industry has grown rapidly, but the quality of products is uneven.
Zeng Yuqun, a member of the National Committee of the Chinese People's Political Consultative Conference and Chairman of CATL, suggested accelerating research on the "passport" and supporting policies for power batteries, and pointed out that battery energy storage requires nuclear power level safety guarantees. According to his vision, "battery passport" is a digital twin of physical batteries, which can achieve transparent digital management of the entire supply chain of power batteries. Consumers and regulatory agencies can easily and directly access relevant information about battery products through the "Battery Passport", which can provide a data foundation for battery carbon footprint, recycling and traceability, and cascading utilization.
National People's Congress representative and Changan Automobile Party Secretary and Chairman Zhu Huarong suggested promoting the standardization of new energy vehicle power batteries and accelerating the development and layout of mineral resources such as lithium.
Meanwhile, currently, China has built the world's largest and most widely distributed charging infrastructure network. According to data from the China Charging Alliance, approximately 54000 new public charging stations were added per month in 2022. As of the end of September 2022, Guangdong Province has 345126 public charging stations and 19116 charging stations.
The demand for DC charging stations is also very strong. Among public charging stations, currently, AC charging stations still dominate, but DC fast charging is expected to accelerate its development. According to the 2021 White Paper on Charging Behavior of Chinese Electric Vehicle Users released by the China Charging Alliance, DC charging stations have become the preferred choice for 99.3% of users.
Pan Helin, co-director and researcher of the Digital Economy and Financial Innovation Research Center at the International Business School of Zhejiang University, is optimistic about the future development of supercharging. Compared to charging, he told the Yangcheng Evening News reporter that battery swapping is more suitable for public rental transportation, but in the private car field, battery swapping is not very suitable and its application scenarios are not wide enough. Therefore, overcharging will be the main development direction for a long time in the future.
However, the "uneven heating and cooling" and "charging anxiety" of public charging stations in various regions still widely exist.
Liu Yong, a National People's Congress representative, director, general manager, and deputy secretary of the Party Committee of State Grid Jiangxi Electric Power Co., Ltd., suggested accelerating the improvement of the new energy vehicle infrastructure construction plan and incorporating charging facility construction into the overall consideration and scientific layout of urban and rural construction planning.
Zhang Zutao, a National People's Congress representative, Director of the Engineering Training Center at Southwest Jiaotong University, and Executive Dean of the School of Innovation and Entrepreneurship, suggested sorting out "zombie piles", releasing station and power capacity, and unifying charging apps.
