Lithium battery protection board equalization principle, lithium battery protection board activation method
battery management system BMS equalization principle, battery management system BMS activation method. As we all know, lithium battery is a new energy battery that will be used in various fields nowadays, but lithium battery needs protection board protection. Many people don’t know that protection board plays a vital role in battery use. Let’s learn about it below. The activation method of the protection board and its protection principle are as follows.
Lithium battery protection board
The lithium battery protection board is a protection for the charging and discharging of the series lithium battery pack; when fully charged, it can ensure that the voltage difference between the individual cells is less than the set value (generally ±20mV), and realize the equal charge of the individual cells of the battery pack , Which effectively improves the charging effect in the series charging mode; at the same time, it detects the overvoltage, undervoltage, overcurrent, short circuit, and overtemperature status of each single cell in the battery pack to protect and extend the battery life; undervoltage protection makes every A single-cell battery is used to prevent damage to the battery due to over-discharge.
The finished lithium battery consists of two main parts, lithium battery core and protective plate. The lithium battery core is mainly composed of positive plate, diaphragm, negative plate and electrolyte; positive plate, diaphragm, negative plate are wound or laminated, packaged, and filled with electrolyte , After packaging, it is made into batteries.
Balance principle of lithium battery protection board
Commonly used equalization charging techniques for the equalization principle of lithium battery protection boards include constant shunt resistance equalization charging, on-off shunt resistance equalization charging, average battery voltage equalization charging, switched capacitor equalization charging, step-down converter equalization charging, inductance equalization charging, etc.
When charging a group of lithium batteries in series, ensure that each battery is charged in a balanced manner, otherwise the performance and life of the entire group of batteries will be affected during use. However, the existing single-cell lithium battery protection chips do not have a balanced charge control function. The balanced charge control function of a multi-cell lithium battery protection chip requires an external CPU; it is realized through serial communication with the protection chip (such as I2C bus). The complexity and design difficulty of the protection circuit are reduced, the efficiency and reliability of the system are reduced, and the power consumption is increased.
In the lithium battery pack protection board system, the charging over-voltage protection control signal of the single-cell lithium battery protection chip in the control circuit part is isolated by the optocoupler and output in parallel to provide the gate voltage for the conduction of the charging switch device in the main circuit; such as a certain section Or several lithium batteries enter the over-voltage protection state first during the charging process, then the over-voltage protection signal controls the discharge of the shunt discharge branch connected in parallel to the positive and negative ends of the single-cell lithium battery, and at the same time connects the corresponding ones in the charging circuit in series. The single lithium battery is disconnected from the charging circuit.
Lithium battery protection board activation method
The protection function of lithium battery is usually completed by a protection circuit board and current devices such as PTC. The protection board is composed of electronic circuits, which can accurately monitor the voltage of the battery cell and the charging and discharging circuit at all times under the environment of -40°C to +85°C. Current, timely control the on and off of the current loop; PTC prevents severe damage to the battery in high temperature environments.
Now not all battery management system BMSs need to be activated, but some protection ICs need to be activated, and this is the old IC solution, the old IC solution. So this is necessary to make the protection board not work to reduce static electricity. Discharge energy so that the lithium battery can be stored longer. This is why the design requires charging activation.
If the lithium battery protection board needs to be activated after charging or completely disconnecting the load due to current limit protection, it is relatively troublesome, but it is also possible to short-circuit B- (battery negative) and P- (discharge negative). One click, the protection will be released, remember not to carry a large load when shorting the connection (such as turning it and twisting it all the time), otherwise it may cause a lot of sparks. The fundamental reason is that the two ends of the discharge MOS are large after the protection. The pressure difference, a short-circuit touch is to directly reset the DS level of the discharge MOS to 0V, and the protection is released at this moment.
How to activate the lithium battery protection board?
If the protection board needs to be activated after charging or completely disconnecting the load due to current limiting protection, it is relatively troublesome, but you can also short-circuit B- (battery negative) and P- (discharge negative). The protection will be released. Remember not to carry a large load when shorting the connection (such as turning it and twisting it all the time), otherwise there may be a lot of sparks. The fundamental reason is that a large pressure difference is formed at both ends of the discharge MOS after the protection. , A short-circuit touch is to directly reset the DS level of the discharge MOS to 0V, and the protection is released at this moment.
The above is the balance principle of the lithium battery protection board and the activation method of the lithium battery protection board.