Let's explore how Tesla manages more than 7,000 batteries

As far as the level of battery management system technology is concerned, there are probably few global and Tesla screams. Tesla's ModelS uses more than 7,000 18650 batteries. How does it manage such a large quantity and the security is not ideal? What about the battery? Why is BYD still doing a good job in the case of battery management system technology is not very strong? As far as the level of battery management system technology is concerned, there are probably few global and Tesla screams. Tesla's ModelS uses more than 7,000 18650 batteries. How does it manage such a large quantity and the security is not ideal? What about the battery? Why is BYD still doing a good job in the case of battery management system technology is not very strong? In contrast, we have seen two aspects of the problem and have a good guiding significance for the development of electric vehicles in China. Before entering the text, let's take a brief look at Tesla. Tesla is an electric car company (Tesla Motors) founded by five Silicon Valley entrepreneurs such as Martin Eberhard and Marc Tarpenning. The company is based on electrical engineer and physicist Nikola Tesla (see foreign countries for their high respect for engineers and technicians). This is the name of the company's cultural heritage. It is designed to accelerate the world's electric mobility, making electric vehicles with more endurance more and more likely to be consumed by the public. The TeslaRoadster pure electric sports car uses an AC motor that was inherited directly from Nikola Tesla's original design in 1882. Tesla began using lithium battery technology in 2006 and developed the first pure electric sports car with a cruising capacity of more than 320 kilometers. The 18650 battery used by Tesla, which maintains long battery life, is a lithium cobalt oxide battery. Lithium batteries are not only a type of lithium cobalt oxide battery, but why does Tesla prefer Panasonic's 18650 lithium cobalt oxide battery? At the same time, what kind of requirements does this battery have for Tesla's battery management system?

1. Why did Tesla choose Panasonic's 18650 battery? Someone might ask Tesla why he chose Panasonic's battery? At present, according to the information I have learned, Tesla also has some helplessness. The previous Tesla technology route was positioned to increase the capacity of a single-cell lithium battery, but the progress was not satisfactory because it relied too much on technological breakthroughs. So later, we could only find other methods, that is, the well-known multi-cell batteries are now combined into blocks, and the blocks continue to be combined into a whole vehicle battery. The capacity of a single battery does not increase to ensure that a long battery life consumes a huge amount of battery. Panasonic NCR186503100mah, in addition to the best test consistency, charge and discharge times, safety is relatively good, the most important thing is the energy, light weight, the price is not high. And when Panasonic supplied Tesla with batteries in the early stage, it was offered at a price of $2 (this was lower than the cost of a Panasonic single-cell battery), which is of course very beneficial to Tesla. While the relatively strong SamsungSDI made by the 18650 battery in the same period is low in price, the low battery capacity is not suitable for electric vehicles, so Tesla chose Panasonic. Most other electric vehicle manufacturers use large batteries, up to a few hundred, and there is no precise control system for each battery.

2. Why is Tesla doing such a complicated battery control system? In order to be able to use the high-performance 18650 cobalt lithium battery, high-performance batteries bring high-performance cars. Because of the high risk of the 18650 cobalt lithium battery, there is no reliable system, and the safety cannot be guaranteed. This is why most manufacturers do not dare to use cobalt-lithium batteries, especially large-capacity cobalt-lithium batteries, regardless of electric vehicles, plug-in buses, and hybrid vehicles. The Tesla top modelS uses nearly 7000 Panasonic NCR186503100mah batteries, grouping the batteries twice, doing series and parallel. The sensor is set to sense the operating status and temperature of each battery and is controlled by the battery control system. Prevent dangerous situations such as temperature difference between overheat and short circuit. In daily use, ensure the safety of the battery under high current discharge. 3. How does Tesla manage more than 7000 batteries? According to Tesla's MODELS, there are 16 battery packs in total, each battery pack has 444 batteries (each 74 sections are connected in parallel, the whole battery board) It is made up of 6 sets of batteries in series). So we can calculate a total of 7104 18650 lithium batteries on this Tesla MODELS85 model. Tesla's battery main control module is completely developed by Tesla. The circuit board uses a large number of resistors and capacitors for signal conditioning. Only one side of the board has six sets of electrical signal acquisition lines. Because Tesla uses 18650 lithium battery, this lithium battery is the battery used in our notebook computer, so its electronic control technology is very mature, but compared to laptop battery, charge and discharge management chip and battery metering management The chip is much more complicated, and its complicated place should be in the multi-channel battery signal acquisition and control algorithm. After all, the monitoring of hundreds of batteries of electric vehicles and the battery monitoring of about 10 sections of notebook computers are not an order of magnitude. In this way, Tesla monitors the battery in real time, maintains the consistency of the battery, and achieves the safety of charging and discharging. With a perfect battery management system, Tesla dares to launch a cobalt-lithium battery with relatively low safety. The high-capacity cobalt-lithium battery provides enhanced battery life for other batteries of the same weight, while Tesla's advanced battery management system ensures battery safety. But several recent battery fires have proved that this solution is not perfect.

If the fish and the bear's paw can't have both, let's see how BYD does it.

4. BYD manages the battery. BYD handles the battery differently than Tesla. BYD pays less attention to the management of the battery system and focuses on the improvement of the performance of the single battery. It is not difficult to understand, compared to Tesla BYD. The original battery technology accumulated, unlike Tesla's elbows in the Panasonic battery. So what is the battery technology that has accumulated a lot of BYD batteries? How to carry out effective management control?

BYD's lithium iron phosphate battery has a high capacity, and it is said that a car can travel to 350 kilometers after a single charge. In addition, lithium iron phosphate batteries are safer than cobalt-lithium batteries, so BYD electric vehicles can be safe without the need for harsh battery management. For example, BYD's electric car is matched with 96 3.3V batteries. The installation position is in the chassis part, which is arranged in 24 vertical and 4 horizontal rows. It should be specially pointed out that lithium iron phosphate can be made into a larger battery, instead of a smaller battery section like a cobalt lithium battery. The comparison between 96 batteries and 7000 batteries can be seen. The requirements for battery management systems are not an order of magnitude. Therefore, it is justifiable that BYD's electric vehicle battery management system lags behind Tesla. 5. What is the enlightenment of the development of China's electric vehicle battery management system? The author has come up with a comparison of the battery management system of BYD and Tesla. It is not to judge the pros and cons. This is two aspects of technology choice. Under the current situation, it is very It's hard to say what's good or bad. Battery management technology has been widely watched in China. Many manufacturers and research institutes are also making research attempts in this area, but compared to the boosted battery capacity, the number of gimmicks is less, but This is an indispensable aspect of the development of electric vehicles. Imagine that the safe battery cell capacity is improved, and the battery management technology in another field is also very mature, so the long-life high-speed electric car is not far away!

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