How to design a safe lithuim ion battery 18650 protection circuit

　　How to design a safe lithuim ion battery 18650 protection circuit? When we design products that require the use of lithium batteries, we need to design a protection circuit for the lithium battery. Only on this basis can we design the charging circuit. The application of lithium iron batteries has also greatly promoted the relative

　　How to design a safe lithuim ion battery 18650 protection circuit? When we design products that require the use of lithium batteries, we need to design a protection circuit for the lithium battery. Only on this basis can we design the charging circuit. The application of lithium iron batteries has also greatly promoted the design and development of corresponding battery management and battery protection circuits. Lithium battery applications must have complex control circuits to effectively prevent overcharge, overdischarge and overcurrent states of the battery.

　　How to design a safe lithuim ion battery 18650 protection circuit?

　　With the rapid increase in the use of lithium-ion batteries in various industries, the safety performance of batteries has become increasingly prominent. Lithium-ion batteries are not only required to have excellent charge and discharge performance, but also have higher safety performance. The performance of lithium-ion batteries mainly depends on the structure and performance of the materials used inside the battery. The internal materials of these batteries include negative electrode materials, electrolytes, separators, positive electrode materials, etc. The selection and quality of positive and negative electrode materials directly determine the performance and price of lithium-ion batteries. Therefore, the research on cheap, high-performance positive and negative electrode materials has always been the focus of the development of the lithium battery industry.

　　The protection function of iron lithium battery is usually completed by the protection circuit board and PTC. The protection board is composed of electronic components. It accurately monitors the voltage of the battery core and the current of the charge and discharge circuit at all times in an environment of -40°C ~ +85°C, and provides timely Controls the on-off of the current loop; the main function of PTC is to protect the battery in high-temperature environments and prevent battery combustion, explosion and other vicious accidents.

　　Lithium battery protection circuit usually consists of control IC, MOs switch tube, fuse, resistor, capacitor and other components, as shown in Figure 2. Under normal circumstances, the control IC output signal controls the MOs switch tube to conduct, so that the battery core is connected to the external circuit. When the battery core voltage or loop current exceeds the specified value, it immediately controls the MOS tube to turn off to protect the battery core. Safety.

　　Lithium batteries require overvoltage charging protection, overvoltage discharge protection, overcurrent discharge protection, short circuit protection, etc. Therefore, when we design a lithium battery protection circuit, we must at least achieve the above protection functions.

　　Lithium battery protection circuit design

　　Due to the chemical characteristics of the lithuim ion battery 18650, during normal use, a chemical positive reaction occurs inside the lithuim ion battery 18650 that converts electrical energy into chemical energy. However, under certain conditions, such as overcharging, overdischarging and overcurrent, the battery will be damaged. A chemical side reaction occurs internally. When the side reaction intensifies, it will seriously affect the performance and service life of the battery, and may produce a large amount of gas, causing the internal pressure of the battery to rapidly increase and then explode, causing safety issues. Therefore, all iron lithium batteries require A protection circuit is used to effectively monitor the charging and discharging status of the battery, and shut down the charging and discharging circuit under certain conditions to prevent damage to the battery.

　　The lithuim ion battery 18650 protection circuit includes overcharge protection, overcurrent/short circuit protection and overdischarge protection. It requires high precision of overcharge protection, low power consumption of the protection IC, high withstand voltage, and zero-volt rechargeability.

　　Lithium battery protection circuit working principle

　　Fake and shoddy lithium batteries have serious quality problems. These fake and shoddy lithium batteries are likely to be overcharged and over-discharged, leading to explosions. It is also possible that short circuits in the internal circuits may occur, causing explosions. However, there is a product that can effectively prevent lithium batteries from overcharging, over-discharging and short-circuiting internal circuits. It is a lithium battery protection board.

　　The lithium battery protection board also has the function of protecting the battery and preventing the battery from overcharging. When the external power supply continues to charge the battery rapidly, the lithium battery protection board will have a protective effect. When the internal power of the lithium battery reaches saturation, the internal circuit of the lithium battery protection board will automatically cut off the external fast charging power supply. This prevents external power from entering the battery. This is also the principle of the lithium battery protection board to protect the battery from overcharging.

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