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The Battery Protection Circuit Board (PCB) Dynamics


The battery protection circuit board, commonly known as the PCB, is the battery management system usually for small batteries. They typically are used for digital batteries. To understand PCBs well, you need to know about battery management systems or BMS. Battery packs, especially the big ones, have power batteries that protect the battery packs from overcharging, discharging, over current, cell balancing functions, and short circuits during battery charging. Some of these batteries need to communicate data with input and output options. The PCB is a management system that works for digital batteries. Examples of these small battery packs include the mobile phone battery, GPS batteries, Music player batteries, camera battery, to mention but a few. The voltage of these batteries varies from 7.4V or 3.7V., and the functions of the PCB play the same functions that BMS plays. It ensures that the batteries do not overcharge, over-discharge, over current, short circuit, and some batteries may need PTC and NTC.

Charges in a battery go through the anode and the cathode. When looking at the lithium battery PCB, the electrons of Lithium go to both the anode and cathode of the battery during the charging and discharging process. To avoid overcharging, the battery charging PCB does not allow the cell’s voltage to go higher than 4.25V. When the battery overcharge, the anode structure may collapse, it can cause a short circuit. Hard crystals may appear. The temperature will rise, and it may lead to a fire. It shows that protection from overcharging.

When dealing with over current and short circuits, it is easy to understand. The battery’s temperature will be higher and higher, which can cause a fire in the battery.

Over discharging should also be avoided since the battery can lose its capacity. It can change from a large ratio to a low level. The voltage is 2.7V and higher for Lithium-Ion battery cells, but over-discharging can cause it to have a lower voltage.

So, for the PCB/PCM of small batteries, these small protections are essential. The BMS of larger battery packs, however, have more functions.


battery control pcb

Battery protection packs can be divided into two categories. The first category is the Protection Circuit Module (PCM) it is also known as Protection Circuit Board or (PCB), And the other type is the Battery Management System (BMS).

In the lithium battery, the battery management system is an essential part of it. The BMS and the PCM ensure that the battery is safe.

The Features of the PCM

The function of the PCM is to protect the charging and discharge of lithium batteries. It is composed of electric hardware components. When battery packs are fully charged, the function of the PCM Is to ensure that there are balanced voltages between different cells. The voltage difference should maintain a set value. In case there is an overcharge or Undervoltage. A short circuit or an over-temperature of the cells, the PCM detects it. It ensures that the battery is protected ultimately and extends the life of the battery.

Modules of Battery Management Systems (BMS)

Simply put, this is the battery manager. It has the same features that the PCM has, but it is more advanced that in that it offers more additional features and protection. Some of these features include monitoring the battery in real time and transmitting data through a designated software. The electrical equipment has the status information. The components of the BMS include a control module, a management system, a wireless communication module, a display module, and a collection module. The collection module functions as a site for collecting information for the battery.

The PCM and PCB are usually found in small battery packs, usually found in digital devices like power tool batteries, electric shavers, mobile phones, and the likes. On the other side, BMS is used in large battery cells like Drone batteries. In the case of a drone operator, they need to check the battery levels in real time. The battery needs to be able to support these types of data transmissions.

Which to choose between PCB and BMS

When deciding to choose a battery management system to help with protection of your battery, you need first to consider the function. The PCM and PCB are used for small battery packs, and they offer low levels of protection. While on the side, BMS has the functions of PCM and other additional properties. When it comes to pricing, the PCM is cheaper compared to the BMS. The best way to get a solution on what to use is to consider the two factors.


For every lithium battery PCB, the protection against overheating is critical. But this also does not mean other measures are not required to ensure that operations are safe when dealing with electronics with lithium batteries.

Primary Safety circuits

The primary safety circuits’ primary functions include undervoltage, overvoltage, over-temperature, under-temperature, and overcurrent. Some other safety circuits are world-class and contain a secondary safety circuit. This second circuit protects the cell in case the first safety fails.

Protection circuits

The PCM contains protection circuits. When considering choosing a PCM, each application has a unique set of parameters to ensure that recommended requirements are met. The PCM is contained as part of the BMS PCB. It monitors and manages the state of rechargeable battery packs being charged. It ensures that the data is monitored and reported. It also balances the cells and controls the environment while protecting the battery.

An integrated circuit usually operates the protection circuits for applications that are more demanding.  The Integrated Circuit (IC) detects when the upper current limit is being reached and interrupts the circuit to protect the battery from over-current protection.

Fail-Safe environments

When choosing a module, you need to know that it was designed in a fail-safe environment. Modules created in a fail-safe environment are not resettable when looking into purchasing a PCM work with a design that can be transferred into another application.

The importance of Protection Circuit Modules


Slowly by slowly, battery cell manufactures are moving from small batteries to large battery cells. Large cells require critical applications. The primary and secondary protection mechanism for PCMs is essential for companies looking at making their devices safe and portable. A good example is the electric car manufacturers.

Different characteristics usually determine the reason that the rechargeable lithium batteries need protection. The material of the battery cannot be overcharged, overcurrent, over-discharge, short circuit.  This element makes it a necessity for any lithium battery to have a protection circuit board.

Protection function of the lithium battery

The protection circuit completes the function of protection of the lithium battery PCB. This device Is usually the PTC, and this component includes a protection board with electronics circuits. The voltage that the battery core should be at an environment of -40 degrees to +85 degrees when charging and discharging the battery.

Protection board principle of the lithium battery

The protection board is usually in three states. Average level, high level, and low level. The principle ensures the detection of overcharge voltage, release voltage of overcharge, detection voltage over-discharge, release voltage over-discharge, overcurrent 1 and 2 detection voltage, long short circuit detection voltage, charger detection voltage, normal operation consumption current, the current consumption of over-discharge.

The battery protection circuit of a typical lithium battery

Lithium batteries’ chemical characteristics cause them to have chemical reactions internally. These reactions between electrical energy and chemical energy are converted. In some situations, the internal battery will overcharge, over-discharge and overcurrent. We also have some side reactions with the chemicals. These reactions seriously affect the service life of the battery and also its performance. They may generate gas in large amounts, which may cause the battery’s pressure to increase and sometimes lead the battery to explode. It can cause some safety problems.

Because of this, all lithium batteries require a protection circuit. The circuit does the work of effectively monitoring the battery during the charging and discharging process. During the charging and discharging process and some side effects occur that the circuit turns off the charging or discharging to prevent any damage from happening to the battery.

Portable chargers with PCB Board

A power bank PCB is an external lithium battery. In itself, it cannot charge a mobile phone directly, but it contains a converter PCB. It converts the charge/voltage. Many products are making more PCBs (Printed Circuit Boards). The PCBs have an IC and also other components that ensure that the circuit is complete.

The PCBs play a significant role in the function of a power bank. It upgrades the battery voltage in the power bank to match up with the voltage required for charging the electronic device. Another quality of a good power bank has a circuit board with the protection of charge and discharge, safety protection circuit, and short circuit protection.

Having a good quality power bank is having one that has a PCB that will allow you to charge more and also have durability. The input and output quality of the power bank is determined by work. There are so many power banks in the market, and it is not easy to distinguish which one has an advantage for how the look. But having some knowledge on how the power ban operates can help you make a better decision.

The 18650 Battery

A 18650 PCB is a lithium battery. The initial four digits of the assignment “18650” demonstrate the actual measurements, while the 5th digit shows its chamber cell. This kind of battery is extremely regular in applications, for example, wireless devices, electric vehicles, flashlights, PC battery packs, and different gadgets that require convenient power. This battery is 18mm, around 65mm long. A few kinds of 18650 have been altered, adding either a catch top or potentially inward security circuit. It can expand the actual length of a “18650” battery from 65mm to 70mm or, in specific cases, considerably more.




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