A BMS is essential for extending the service life of a battery and also for keeping the battery pack safe from any potential hazard. The protection features available in the 4s 40A Battery Management System are: 1. Cell Balancing 2. Overvoltage protection 3. Short circuit protection 4. Undervoltage protectionThe schematic of this BMS is designed using KiCAD. The complete explanation of the schematic is done later in the article.The BMS module has a neat layout with markings for connecting the BMS with different points in the battery pack. The image below shows how we need to connect the cell with BMS. The BMS acts like 4 separate modules for 4 separate cells and then these 4 modules are very smartly integrated together with transistors and passive components to make a com. The BMS has 2 ICs, DW01, and BB3A; some variants of this BMS may have the same ICs or similar ICs from different manufacturers. But all the ICs will have the same pinouts and functioning. I will be discussing the 2 ICs later. The figure below shows the parts of BMS responsible for different operations. From the above image, it is clear that one IC. The above image shows the complete circuit diagram of the BMS circuit, as discussed above the circuit can be divided into smaller modules for balancing and monitoring every single cell. As shown in the image below, we can see that the Balancer IC is connected in parallel with the cell. Similarly, the Battery charging IC, DW01 is also connected in p.