6S - BMS Based on STM32

Battery Management System (BMS) is any electronic system that manages a rechargeable battery. In case of this particular BMS, there is a self-made battery pack with 21700 cells in 6S4P configuration (max 25,2V) that will be managed.

Few words about why this PCB was created in the first place. It is a part of much bigger project made by PUT Motorsport, which is a racing team of the Poznan University of Technology. We have been designing, manufacturing and testing racing cars continuously since 2014, and then checking them during the international competition where teams from all around the world compete. It should be noted that many design decisions are dictated by the regulations that we have to follow when building a racing car.

So presented circuit is one of the most important ones, as it is the low voltage battery that powers all the systems in the car.

Some important functions this PCB will include:

• Voltage monitoring on individual cells (6S – 6 measurement points),

• Temperature monitoring on 33% of all cells,

• Battery current consumption monitoring,

• Battery protection against critical errors specified in the regulations of Formula Student Germany. In the event of an error, the battery power is disconnected from the rest of the car's systems thanks to my eFuse,

• Battery cell balancing system while charging,

• Information processing and sending via serial port (for user) and CAN (for other car systems),

• Voltage measurement point behind fuse placed on the main current path (so there is information about blown fuse).

Voltage monitoring and cell balancing is done by LTC6810-2 via SPI.

PCB manufactring supported by https://jlcpcb.com/HAR 

Author: Maksymilian Jaruga

More details & updates:

https://github.com/PUT-Motorsport/PUTM_EV_BMS_LV_2022.

Full schematics:

PCB Layout

To get the PCB manufactured, upload zipped Gerber files as you can see below. How to get them in KiCad 5? JLCPCB made the whole tutorial right here:

https://support.jlcpcb.com/article/149-how-to-generate-gerber-and-drill-files-in-kicad.

Now that we’ve got the PCB design, it’s time to order. For that, you just have to go to jlcpcb.com, and click on the “Instant Quote” button.

You don’t have to worry about the settings here, because you can adjust everything in the new appeared tab.

JLCPCB is also a sponsor of this whole project (not only this PCB, but all the PCBs in the car!). JLCPCB (Shenzhen JLC Electronics Co., Ltd.), is the largest PCB prototype enterprise in China and a high-tech manufacturer specializing in quick PCB prototype and small-batch PCB production. You can order a minimum of 5 PCBs for just $2 (2 layers), just enough to have a few test/spare ones. After making sure your PCB looks good – by clicking Gerber viewer, you can now place the order at a reasonable price. In case of this project, there is 8$ for 5, 4-layers PCB and it’s only 6-7 days build time(the time is extended due to the chosen colour). To place the order, click on the “SAVE TO CART” button.