Can lithium battery packs do not need a protection circuit board? Is it necessary for protection circuit board of a lithium iron phosphate battery pack to be useful? What happens if the lithium battery does not have a protection circuit board? Generally, batteries have a protection circuit board, and the use of the protection circuit board is also for battery safety. But different types of battery protection circuit boards have different functions. I heard that lithium iron phosphate battery packs are not afraid of overcharging or over-discharging, so some people think that lithium batteries do not need a protective circuit board. Today we will answer these questions for you.
What is a lithium battery protection circuit board?
The lithium battery protection circuit board, as the name suggests, is used to protect the lithium battery. The lithium battery protection circuit board is designed to avoid problems such as overcharging, overdischarging, overcurrent protection, short circuit, etc., and some smart chips are installed to record the usage and status of the battery.
The lithium battery pack protection circuit board is the charge and discharge protection of the series lithium battery pack, detecting the overvoltage, undervoltage, overcurrent, short circuit, and overtemperature status of each single cell in the battery pack, protecting and prolonging the battery life. For example, when the battery is discharged, the protection circuit board will protect the battery from over-discharge and cause battery damage. This adds a protective barrier to the lithium battery, making the lithium battery pack safer and prolonging its service life. If there is no protection circuit board, the battery life will not only be affected, but also dangerous situations will occur in serious points.
Can the lithium battery pack be without a protective circuit board?
As to why some people have the idea that lithium battery packs do not need to protect the board, a big reason lies in the emergence of lithium iron phosphate batteries. Because there is news that lithium iron phosphate battery packs are not afraid of overcharging or overdischarging, there has been the argument that lithium batteries can be used without a protective circuit board. However, so far, there has not been a battery manufacturer that publicly declares not to use the protection circuit board.
The lithium battery pack protection circuit board is the charge and discharge protection for the series-connected lithium battery pack. When fully charged, it can ensure that the voltage difference between the individual cells is less than the set value, realize the equal charge of the individual cells of the battery pack, and effectively improve the charging effect in the series charging mode.
When the lithium battery is completely immune to overcharge, overdischarge, etc., when the lithium battery can completely replace the protective circuit board in the design of the lithium battery itself, the lithium battery does not need the protective plate, but at this stage, the lithium battery pack is still Need to protect circuit board. Of course, the protection circuit board will damage the battery if the protection circuit board is not well designed. Therefore, when purchasing lithium battery packs, it is best to buy lithium batteries produced by regular manufacturers through regular channels. In this case, the quality of lithium batteries is more guaranteed.
What if the lithium battery pack does not have a protective circuit board?
If the lithium battery pack does not need a protection circuit board, for some users who do not pay attention to the daily protection of the battery, the service life of the battery will be greatly reduced, and more failure problems will occur, leading to some dangerous situations.
During the use of lithium batteries, every time they are overcharged, over-discharged, or short-circuited, the battery life will be reduced. In severe cases, the battery is directly scrapped! Generally, the overcharge voltage of a single-cell lithium battery cannot exceed 4.25V, the overdischarge voltage cannot exceed 2.75V, and the maximum charge and discharge current is 1C (C represents the battery capacity, for example, the battery is 1200mAh, and the 1C charge and discharge current is 1.2A), if there is no protection circuit board, directly short-circuit the lithium battery pack and overcharge it will cause the battery to bulge. In severe cases, it will leak, depressurize, explode or catch fire.
The main functions of the lithium battery pack protection circuit board:
1) Overcharge protection function
The overcharge protection function means that when a certain voltage (hereinafter referred to as the overcharge detection voltage) is reached, it is forbidden to continue charging by the charger. That is, the MOS tube that controls overcharge is turned off to stop charging.
2) Over-discharge protection function
The over-discharge protection function stops discharging the load when the battery voltage drops. The MOS tube that controls the over-discharge enters the off state, and it is prohibited from discharging. This process is just the opposite of the action during overcharge detection.
3) Overcurrent protection function
The over-current protection function is to stop discharging the load when a large current is consumed. The purpose of this function is to protect the lithium battery pack and MOS tube to ensure the safety of the battery under working conditions. After the over-current detection, the battery will return to the normal state after being separated from the load, and can be recharged or discharged.
4) Short circuit protection function
Does the lithium battery pack protection circuit board need a balance function?
It is necessary for the protection circuit board of the lithium battery pack to be balanced: when the battery pack is produced and stored for a long time, due to the different static power consumption of the protection circuit board and the different self-discharge rate of each battery cell, the entire battery pack is formed. The voltage of the battery string is inconsistent, so there is a significant pressure difference, but when the capacity is consistent, the equalization has the function of equalizing the voltage of the battery pack, so as to achieve the effect of full charge and full discharge of the battery pack capacity, so that the battery pack can play Maximum efficacy.
The situation where the balance does not work: Many people think that the balance of the lithium battery pack is effective in the middle and later stages of use. In fact, when the battery pack is used in the middle and later stages, due to the different capacity losses of each battery cell, a capacity difference is caused. Relying on the equalization of the protection circuit board cannot make up for the cell capacity. On the surface, the voltage of each string of the battery pack is the same, but due to the inconsistency of the capacity, the single string cell with low capacity is often over-discharged and over-charged during charging and discharging. Protection, so the capacity of the battery pack is reflected in a single string of cells with low capacity. Therefore, we should understand that the protection circuit board balances the voltage, and the capacity cannot be supplemented.
In summary, the reason why the lithium battery pack needs protection is determined by its own characteristics. Since the material of the lithium battery itself determines that it cannot be overcharged, overdischarged, overcurrent, short circuited, and ultra-high temperature charged and discharged, lithium batteries and lithium battery components will always follow a special lithium-ion battery protection circuit board. It is necessary for the lithium battery pack protection circuit board to be useful. The protection circuit board can separately detect the voltage and current of each battery in the series battery pack, and control the charging and discharging process of the battery pack.