On July 18, an electric car caught fire and exploded while driving near Yuhuang Villa in Hangzhou. The father and daughter in the car were severely burned. The cause of the fire was determined to be the failure of the lithium battery that was replaced later. According to data released by relevant departments, more than 2,000 electric vehicle fires occur across the country every year, among which lithium battery failure is the main cause of electric vehicle fires.
To this end, the reporter conducted an interview with Wuxi, Jiangsu Province, which mainly produces electric vehicles, to learn more about the battery replacement situation of electric vehicles.
Wuxi, Jiangsu: Replacing lithium batteries is a common phenomenon
Mismatched chargers pose safety risks
On July 18, an electric car caught fire and exploded while driving near Yuhuang Villa in Hangzhou. The father and daughter in the car were severely burned. On the 19th, the Hangzhou Fire Brigade initially determined that the cause of the fire in the electric car was the lithium battery that was replaced later. Fault. The reporter conducted interviews on the streets of Wuxi, Jiangsu. Citizens generally reported that lithium batteries are lighter in weight and larger in capacity than traditional lead-acid batteries in the same volume. Many people will replace the lithium batteries themselves after purchasing lead-acid battery electric vehicles.
During the interview, the reporter learned that most consumers do not know the battery types of their vehicles. Many consumers admit that they usually replace batteries in modification shops on the street and continue to use their previous chargers.
Jin Yuan, chief engineer of an electric vehicle group research institute: It is very dangerous for lead-acid battery chargers to charge lithium batteries because the voltage of lead-acid batteries will be higher than that of lithium batteries if they are on the same voltage platform. The voltage of the charger. If the lithium battery is charged at this voltage, there will be a danger of overvoltage. In severe cases, it will directly burn.
Industry insiders told reporters that many electric vehicles have decided at the beginning of their design that they can only use lead-acid batteries or lithium batteries and do not support replacement. Therefore, many modification shops need to replace the electric vehicle controller when replacing the battery, which will have a negative impact on the vehicle. Security is affected. In addition, whether the charger is original is also a key point that consumers need to pay attention to.
The average price of qualified lithium batteries is 700 yuan. The safety of low-priced brands cannot be guaranteed.
Most current electric vehicles are sold with batteries and vehicles separated. When consumers purchase electric vehicles, they can choose to have the batteries replaced by dealers or stores. Due to the lack of strong supervision, many unbranded batteries are also flooding the market, which brings great hidden dangers.
The reporter visited a number of battery stores in Wuxi, Jiangsu. The store told reporters that replacing the battery is very simple, but due to the recent lithium battery explosion incident, they do not recommend replacing the battery.
The reporter found that the average price of lithium batteries sold in most stores is nearly one thousand yuan. However, in a store, the reporter saw a 48V lithium battery priced at only more than 400 yuan.
When the reporter searched for lithium batteries on the Internet, he found that many low-priced lithium batteries did not have the manufacturer marked on the product page, and the warranty was only one year.
In a lithium battery manufacturing company in Huzhou, Zhejiang, the reporter learned. Lithium batteries are mainly composed of battery cells and BMS systems. In order to ensure safety, the battery core is designed with a safety valve, and the BMS system is responsible for cutting off the circuit when the battery is short-circuited. In order to ensure safety, the casing of lithium batteries also needs to undergo vibration and drop tests and high and low temperature impact tests. A qualified 48-volt lithium battery generally sells for more than 700 yuan, and lithium batteries that are too cheap may lack the necessary safety guarantees.
Hao Yuliang, deputy general manager of a lithium battery company in Huzhou, Zhejiang: There are several main ways to produce this extremely low-cost battery. Because many batteries so far can be dismantled and reprocessed, secondary use of batteries is part of the process, and its cost will be extremely low. The second part is that the production of lithium batteries actually has extremely strict requirements for the environment and equipment. The investment in this part is actually very large. When such equipment and environment are not available, lithium batteries can actually be produced, but There is no way to guarantee the quality or safety of the production of this lithium battery, but its cost is low.
Since the battery space reserved for branded electric vehicles is limited, if consumers want to improve the battery life of their electric vehicles, they can only replace the battery with a larger capacity battery of the same volume, which also creates hidden dangers for future use.
Actual fire test in Shanghai: Lithium batteries are damaged due to high temperature and can easily cause explosions
So, why do electric bicycles frequently catch fire? How can safety hazards be avoided? In order to answer this question, Shanghai fire protection staff conducted an experiment.
The firefighters first placed the lead-acid battery in a combustion barrel that simulated a high-temperature environment. The reporter saw that the lead-acid battery continued to burn but did not explode.
Then the firefighters placed three 3.7V single-core lithium batteries in the burning barrel. The reporter saw that after a few minutes, the single-core lithium batteries had jet fire and formed a small area of flashover.
Finally, the firefighters placed the 48V lithium battery in the burning barrel. In just two or three minutes, the lithium battery exploded, and the broken explosives were sprayed five meters away.
Yang Weiwen, Supervisor of Shanghai Yangpu District Fire Rescue Detachment: Because of the combustion characteristics of lithium batteries, it mainly presents explosions and flashovers. Therefore, after a fire occurs, you must escape quickly and use isolation methods to block surrounding combustibles.
Shanghai firefighting staff told reporters that in addition to high temperatures, damage and extrusion of lithium batteries are also important causes of electric bicycle fires. The reporter came to the Shanghai Disaster Prevention and Relief Laboratory located in Lingang New District. In the experimental area, the staff pierced a single-cell lithium battery with a steel needle at a constant speed. The reporter saw that after a few seconds, the battery began to smoke and was accompanied by jet fire, and then exploded.
Shanghai firefighting staff reminded that batteries purchased through informal channels may have the risk of being recycled and reassembled. Some consumers blindly purchase high-power batteries that are not suitable for electric bicycles in order to reduce the number of charging times, which is also very dangerous. Yang Weiwen, Supervisor of Shanghai Yangpu District Fire Rescue Detachment: We must purchase electric bicycles through formal channels, and at the same time, we must use matching chargers for daily charging. During our daily driving, we should try to avoid bumps and collisions. At the same time, we should also observe the appearance of the battery and repair and replace it in time if necessary.
Post time: Dec-19-2023