Electric vehicle battery monitoring system utility geometry?

At present, many battery group companies in China are not sufficiently aware of the importance of BMS. They believe that as long as the individual cell cores can be linked, they can guarantee the vehicle's operation. They are lucky to have their safety. They are pursuing low prices in BMS procurement. In order to sign the contract, the BMS supplier has only reduced certain indicators and functions, which also left hidden trouble for the battery failure.

Since the incident of self-ignition between Hangzhou Zhongtai pure electric taxi and Shanghai 825 road electric bus, consumer attention to the safety of new energy vehicles mentioned an unprecedented height.

On the day before the deadline, the reporter visited the largest automobile trading market in Beijing's East Wuhuan District - Yaojiayuan Oriental Base Auto Market, and conducted a questionnaire survey on "Influencing Consumers' Purchasing New Energy Vehicles," and interviewed 50 people randomly. Potential customers that energy vehicles understand or focus on. The results of the survey were surprising: About 90% of the population identified the primary concern as safety rather than the previously envisaged price factor; 80% knew or probably knew about the above-mentioned spontaneous combustion event.

On August 18th, four ministries and commissions, including the Ministry of Science and Technology, the Ministry of Finance, the Ministry of Industry and Information Technology, and the National Development and Reform Commission, jointly issued the “Safety Order” for the demonstration and promotion of new energy vehicles (ie, the “Letter on Strengthening the Safety Management of Energy Conservation and New Energy Vehicles Demonstration and Promotion”). Stressed that “plug-in hybrid electric vehicles and pure electric vehicles that have been put into demonstration operations should all be equipped with real-time monitoring systems for vehicle operating technology (BMS), and in particular, the monitoring of the working status of the power battery and fuel cells should be strengthened.”

According to industry analysts, this notification will put the safety of new energy vehicles on the right track and re-establish public confidence in new energy vehicles. But Han Jingke, general manager of Shanghai Boqiang Microelectronics Co., Ltd., believes that BMS is as important as the quality of the battery pack and plays a crucial role in avoiding battery burn.

The fundamental reason for spontaneous combustion is the battery?

Since the incident of self-smearing by Zhongtai, the public questioned the safety of new energy vehicles, which directly affected the public's confidence in the consumption of new energy vehicles.

On June 8th, the Hangzhou Municipal Government reported on the identification result of the “batteries that failed to meet the requirements of the vehicle's use environment after the formation of batteries, and the battery leakage, insulation damage, and partial short circuit”.

After the results were announced, an industry expert who did not wish to be named analysed the reporter. There are several possibilities for spontaneous combustion of the battery: First, the battery itself, problems with the materials and production process, and then the monitoring system appears after the battery is grouped. The problem has not played its due function; again the problem of the plugging system, the resistance at the interface is too large, causing a short circuit. Of course there may also be problems with circuit electronics. As long as the car is used for several months, the possibility of the latter two problems is very low.

“At present, the production level of domestic single cell batteries is not very different from that of the world. However, the consistency of battery cells after group formation is very different. Many manufacturers still stay in the manual production stage, which makes it difficult to ensure battery group consistency.” Lanke Electric Motor Technology Co., Ltd. Ma Jun told reporters.

When talking about the status quo of domestic battery group related standards, Zeng Lingpeng, deputy general manager of Chery New Energy Automobile Co., Ltd., stated that although the national unified battery battery testing standards have not yet been introduced, some companies include technology paths and technological R&D levels according to their own conditions. The different, but also formed a different version of the corporate standard, these corporate standards will continue to improve as the technology continues to mature.

Surveillance system is not "helping the grass"

According to industry insiders, installing BMS can effectively improve battery utilization, prevent overcharging and overdischarging of batteries, and prolong the service life of batteries, monitor the operating status of battery packs and individual batteries, and make unexpected incidents to drivers in advance. Early warning, to win time for security.

However, according to a survey conducted by the reporter, as early as before the Hangzhou Zhongtai pure electric taxi spontaneously took off, the vehicle had been equipped with a BMS system with a universal battery pack manufactured by Wanxiang Group (Industry).

Han Jingke analysis pointed out that BMS and power battery pack quality are equally important and play a vital role in avoiding battery burning.

Prince Dong gave an example for reporters to emphasize the importance of the two: "Currently, the results of single cell, small module battery test and grouped results are quite different. The single cell battery meets safety and performance standards and does not mean The group's performance and safety are guaranteed, and the single cell can be charged and discharged 2000 times in terms of safety, lifespan, and discharge capacity, and may only be 1000 times after group formation. Local core power consumption is too large, local heat is generated, and information cannot be transmitted to the driver, which can easily lead to battery self-ignition.This indicates that the battery grouping technology needs to be improved, and on the other hand, the importance of BMS for group operation is explained. ”

“The power battery is assembled into a complete vehicle in a group form. The quality of the battery, the assurance of safety, and the stability of performance all require feedback from the BMS,” he said. However, the BMS system can only be used as a fault monitor for the operation of the battery pack. Yang Zhiwei, general manager of Taiwan Li Kai Energy Technology Co., Ltd. China, told reporters that the BMS real-time monitoring system has the function of transmitting battery pack fault signals to drivers and dashboards, but even at high speeds, even if it is discovered in time, if there is no professional knowledge. The consequences are still hard to imagine. Only the battery quality is excellent, BMS can realize the safety of the power battery.

Defects in the monitoring system itself "Because of the absence of basic technical parameters and standards for BMS in China, there is no authority to test the BMS produced by manufacturers, so it is difficult to ensure quality and large-scale promotion." Han Jingke said.

He also pointed out that at present, many battery group companies in China have insufficient understanding of the importance of BMS, as long as the individual battery cells can be linked, they can guarantee the vehicle's operation, and their safety is only a matter of luck. Pursue low prices. In order to sign the contract, BMS suppliers only have to reduce certain indicators and functions.

When discussing whether China's battery technology is synchronizing with foreign countries, some industry experts believe that battery battery testing has the greatest gap with foreign countries. Yang Zhiwei expressed this recognition: “At present, most domestic BMSs are still in their respective market patterns. There are dozens of BMS companies, but only a few European and American developed countries have a higher degree of specialization,” Yang Zhiwei told reporters. Currently in the field of BMS systems, the real core international competitiveness is mainly concentrated in US listed companies such as Texas Instruments, O2Micro, and Linear Technology. Domestic battery suppliers basically use their own BMS systems. Compared with the former, the price is relatively low, but its stability and safety are poor. It mainly supplies domestic battery group companies.

“The occurrence of spontaneous self-ignition incidents in Zhongtai electric vehicles is not accidental. This is exposing the current domestic imperfections in the design, testing and standardization of battery packs for pure electric vehicles,” said an industry expert.

"Battery grouping is by no means a simple superposition of single cells, and involves many complicated techniques. The testing and testing of battery group design is necessary, and a set of criteria is needed to evaluate the basic performance and safety of battery groups. "Prince Winter said.