Analysis of CR2032 button cell battery Management System BMS Design and Function

CR2032 button cell battery Management System BMS Design and Function. LiFePO4 batteries have better life and safety, and are more suitable for plug-in hybrid vehicles. BYD new energy vehicles will appear more and more in our lives. When using new energy vehicles, people are generally concerned about battery issues. It is understood that the charging modes of "Qin" mainly include scheduled charging and instant charging. It can charge the vehicle at scheduled time according to the charging time set by the customer, and can also charge the vehicle directly at random.

CR2032 button cell battery Management System BMS Function CR2032 button cell battery BMS Management System is not dispensable as some battery manufacturers say, but must be available, and it must be used throughout the application of lithium battery packs. BMS lithium battery management system has been studied a lot at home and abroad, and has begun to be applied in many fields. It can already meet the needs of some markets. The application of lithium power batteries has put forward higher requirements for battery management systems. Ensuring the safe use of power battery packs is the primary task of lithium power battery management systems. The power BMS lithium battery management system can effectively monitor, protect, balance energy and alarm faults of lithium battery packs, thereby improving the working efficiency and service life of the entire power battery pack. Lithium iron phosphate batteries are widely used in various precision equipment due to their many advantages such as high working voltage, small size, light weight, high energy density, no memory effect, no pollution, low self-discharge, and long cycle life.

Although lithium iron phosphate batteries have more advantages than other types of batteries, lithium batteries are still at risk of explosion when they are in a serious overcharge state, which not only damages the lithium battery pack but also threatens the user's life safety. Therefore, it is necessary to equip the lithium battery pack with a set of targeted lithium battery management system BMS to effectively monitor, protect, balance energy and alarm faults of the battery pack, thereby improving the working efficiency and service life of the entire lithium battery.

The lithium battery BMS management system has the following characteristics

●The lithium battery management system consists of a management host (CPU), a voltage and temperature acquisition module, a current acquisition module and a communication interface module.

●Can detect and display the total voltage, total current, and reserve power of the lithium battery pack; the voltage of any single cell and the temperature of the battery box; the highest and lowest single cell voltage and battery number, the highest and lowest temperature, and the charge and discharge capacity of the battery pack.

●UPS battery host also provides alarm and control output interface, alarm and control output for extreme conditions such as overvoltage, undervoltage, high temperature, low temperature, overcurrent, short circuit, etc.

●Provide RS232 and CAN bus interfaces, and all information on the lithium iron phosphate battery management system can be directly read on the computer.

BYD lithium iron phosphate battery management system BMS design analysis First, let's talk about the batteries of BYD Tang and Qin. The model should be the same, but Qin's lithium battery pack has fewer cells and a capacity of 13 degrees, while Tang has more, 18 degrees. The individual cells are all lithium iron phosphate batteries manufactured by BYD itself, with a rated voltage of 3.2V and a capacity of 26AH. Why not the recently popular ternary lithium battery?

The reason is as shown in the figure below: Lithium iron phosphate batteries have better life and safety, and are more suitable for the use of plug-in hybrid vehicles. The battery cell platform looks like this, but this one should be on the bus, because the power storage capacity is as high as 120AH, and ours is only 26AH, but they are roughly the same, both are rectangular. Tang's BMS battery pack is located in the middle of the chassis, and its size and weight are relatively large. The advantage of placing it on the chassis is that it lowers the center of gravity of the entire vehicle, while not affecting the trunk space. The disadvantage is that it has high requirements for water discharge and anti-collision. In daily use, you should pay attention to this part not to soak in water or bump. Qin's BMS lithium battery pack is located behind the back seat and before the trunk.

Advantages: good water discharge and anti-collision performance, disadvantages: high center of gravity, affecting the trunk space, just opposite to Tang~. The connection method is series connection. To put it in a more vivid way, it is similar to the flashlight we used before, with several batteries connected head to tail. In this connection method, each battery cell uses the same current to discharge when discharging, and the same current to charge when charging. Without the help of a balancing system, it is impossible to charge and discharge a single battery cell. Moreover, when a cell is full, the charging of the entire BMS lithium battery pack must be stopped, otherwise the cell will be overcharged and damaged, and when a cell is empty, the entire battery pack must stop discharging, otherwise the cell will be over-discharged and damaged.

BMS lithium iron phosphate battery management system's balancing module. The balancing module of Tang and Qin adopts a passive balancing method, that is, the cell with higher voltage is discharged through a bypass resistor to make it reach the same voltage as other cells. That is to say: each cell has a resistor controlled by the lithium iron phosphate battery management system alone. When needed, the circuit of this resistor is connected to discharge the cell.

Because the battery packs of BYD Tang and Qin are unbalanced, most of them are one or two cells with too low voltage, and a large number of other cells need to be discharged. When the battery is low, the remaining cells can be correctly marked. When the battery is high, the system will only mark the cell with the highest voltage when it is full. It is one, and you can imagine how efficient it is, which can be almost ignored. The reason why BYD insists on using lithium iron phosphate batteries is that lithium iron phosphate batteries refer to lithium-ion batteries that use lithium iron phosphate as the positive electrode material. The positive electrode materials of lithium-ion batteries mainly include lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, ternary materials, lithium iron phosphate, etc.

Among them, lithium cobalt oxide is the positive electrode material used by most lithium-ion batteries at present. Lithium iron phosphate battery is a domestically produced lithium battery developed completely independently by BYD, with huge investment. It is now a mature product and has been widely used in China; although compared with foreign lithium battery products, the characteristics of lithium iron phosphate battery are not perfect, but because of its existence, it has broken the foreign technology monopoly and created a path for us to take our own lithium battery research and development route, so we admire its spirit very much. In addition, BYD insists on using lithium iron phosphate batteries without explosion. In fact, Chinese companies have mastered the world's most advanced technology and process for lithium iron phosphate batteries. The absolute advantage of lithium iron phosphate batteries over ternary lithium batteries in safety and cycle life is the key element and development need of China's new energy vehicles. As long as its development status is clarified and investment is increased to solidify this advantage, China's new energy vehicles will have the possibility of overtaking on the curve.

The material formula of ternary lithium battery, whether it is lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminum oxide, cannot do without two precious metals, namely cobalt and nickel. Both metals are scarce in China and have limited reserves in the world. Lithium iron phosphate battery is just the opposite. It does not contain any precious metals, and the main raw materials for producing positive electrode materials, iron oxide and lithium carbonate, are very abundant in China. If the demand for downstream new energy vehicles is enlarged, the cost of its upstream materials will plummet under the impetus of scale effect. The decline in the price of positive electrode materials, which accounts for more than 30% of the cost of lithium iron phosphate batteries, will prompt a rapid decline in the price of lithium iron phosphate batteries. Lithium iron phosphate battery is the core component of BYD's new energy vehicles, providing driving power for the whole vehicle. It is mainly wrapped in a metal shell to form the main body of the battery pack protection. The battery cell realizes the integration of the battery cell through modular structural design, and includes the heat dissipation hardware of the battery cell. The quality of the heat dissipation system design is the prerequisite for BMS to achieve excellent management.

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