As the name suggests, a Battery Management System (BMS) is an integrated circuit board primarily designed to protect rechargeable batteries, particularly lithium-ion batteries. The BMS plays a crucial role in enhancing battery utilization, preventing overcharging and overdischarging, extending battery lifespan, and monitoring battery health.

It helps us to analyze the BMS control board of Great Wall Euler Automobile designed for Beehive Energy by analyzing the BMS control board of Euler Haomao Automobile.

The compatible car model is likely the Euler Haomao, and the battery pack with this control board is shown below:

The BMS acquisition board and bms control board are arranged on top of the battery, and the cell sampling is connected through a wire harness, similar to a centralized type.

The front of the BMS control board is shown below. Its size is about 220mm120mm20mm, which is relatively thin. The housing is divided into two upper and lower parts, made of plastic (PA6-GF15), and is black. The protection level is about IP3X, and the entire product is fixed through the installation feature holes on the left and right sides of the housing, with a total of four, and the asymmetric structure is used to prevent mistakes.


The upper and lower housings are connected by snaps. To remove the lower housing, expose the inner PCBA, as shown below:The PCBA is fixed to the upper housing with four screws.


Remove the screws and take out the PCBA board, as shown below:

The screws are fixed at the four corners, corresponding to the four metallized vias reserved at the four corners of the PCBA.


Next, let's take a look at this PCBA. The T side is shown below:

Its approximate size is 182mm115mm12mm, the PCB is green overall, 6 layers, 1.6mm thick; three-proof paint covers all components, and the three-proof paint material is quite hard.


Look at the local details, the PCB surface treatment is ENIG, the vias are filled with green oil, the location numbers of components and test points are all displayed with silk screen, and the smallest component package on the board is 0402.


What is the difference between PCB and PCBA

PCBA = Printed Circuit Board Assembly. It is PCB bare board assembled with various ICs, capacitors, resistors, connectors and other electronic components to form finished products. That is to say, the empty PCB circuit board firstly passes through SMT and then passes through DIP insert, the semi-finished product of PCB+components becomes PCBA, and it is also called PCB'A. in some countries.

PCB = Printed Circuit Board, PCB is the substrate underneath the PCBA, PCB is the connecting carrier of electronic components. Since it is made by electronic printing, it is called “Printed Circuit Board”. PCB substrates are generally classified by the insulating part of the substrate, and the common raw materials are bakelite, fiberglass, Teflon, ceramic, copper, and aluminum.

What is the difference between gold plating and gold sinking in PCB surface treatment

Here I would like to add a piece of knowledge, that is, the difference between gold plating and immersion gold in PCB surface treatment, as explained below. In addition, some people say that ENIG is a kind of immersion gold process, and some people say that it is a combination of gold plating and immersion gold. I tend to agree with the latter. Generally, ENIG process is used more in automotive electronic components.


The B side of the PCBA is shown below:

In addition to resistors and capacitors, there are also some chips and diodes arranged on this side. Overall, there is still some space, and the three-proof paint also covers all components.


There are a total of 6 connectors on the entire board, distributed on two adjacent sides of the board. Among them, the two on the left are pin-type, which seem to be used for high-voltage sampling input. The PITCH is relatively large. From the board, it can also be seen that this controller integrates high-voltage sampling. There is a clear isolation strip on the PCB; the bottom side is four patch-type connectors, the three on the right are used for low-voltage signal transmission, and the one on the left looks like a daisy chain communication. In addition, no current shunt for current sampling is currently seen on the board, and it is not yet clear whether it is arranged outside or using a Hall sensor.

This time, only the structure, process and other information are introduced, and the circuit modules will be analyzed later.


In recent years, I have analyzed many excellent BMS products in a vertical direction. I plan to compare them horizontally in the future. With a certain function as the goal, I will compare the differences between each company to see if there are any innovative ideas that can be summarized. The above is for reference only.

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