3-192S Arduino BMS (using BQ76PL536A)

[dmwahl]

Just wondering if any soul is still working on the project?

I'm still working with the core part to this project (TI BQ76PL536A). I've designed a number of systems around it, many of which are in commercial production right now. As far as making it available, the cost relative to what most people spend on building packs out of hobbyking lipo and 18650 cells makes it a non-starter in light of all the cheap chinese BMS boards (which can work just fine). It's really much better suited to larger systems (ie 40Ah and up) that are produced in quantity. Sorry maybe not the answer you were looking for, but my opinion at least.

 

[msrinivasan1995]

Just wondering if any soul is still working on the project?

I'm still working with the core part to this project (TI BQ76PL536A). I've designed a number of systems around it, many of which are in commercial production right now. As far as making it available, the cost relative to what most people spend on building packs out of hobbyking lipo and 18650 cells makes it a non-starter in light of all the cheap chinese BMS boards (which can work just fine). It's really much better suited to larger systems (ie 40Ah and up) that are produced in quantity. Sorry maybe not the answer you were looking for, but my opinion at least.

Can u share me your schematic.? i need a bms system for 60 Ah.

 

[dmwahl]

Schematics are linked on the first page. PM me if you are looking for professional assistance with your project.

 

[MikeLemon]

It took a few revisions, but I finally am happy with the schematic and layout of my BMS boards. I ended up going the modular route for now, each board handles 3-6 cells, and can be expanded up to 192 cells via a standard 10-pin (2x5) cable. The stack of BMS boards fits onto an Arduino Uno.

The only missing part before it could go on a bike (or elsewhere) is a power supply. I'm currently powering the Arduino board through my computer's USB port, but am working on a design to step down the full pack voltage to 5V to power the Arduino. It will bypass the inefficient 5V regulator on the Arduino, thereby substantially lowering the power draw. I'm estimating around 50-100uA of average draw from the battery pack when using the ATmega's sleep modes. (Using one of those portable cell phone battery chargers with a USB port to power the Arduino instead, main pack draw can theoretically be as low as 12uA due to the BQ76PL536A chips). It will be limited to 140V main pack voltage, which is enough to get up to ~32S lipo. And because I know someone will ask... Yes, the current draw is even across all the cells, so it will not cause imbalance of the pack.

Sample of the board readings below. The two numbers after cell readings are temperature, the first is an on-board thermistor to monitor BMS temp and the second is off-board for monitoring cell temps (not connected at the moment). When I took the readings below the board was cooling down after a test of the balance resistors, hence the decreasing temperature readings. A reading of 4500 corresponds to about 25C, or 76F:

Cell 1: 3284.00mV
Cell 2: 3290.38mV
Cell 3: 3279.31mV
Cell 4: 3280.84mV
4508.00
30.00
---
Cell 1: 3285.00mV
Cell 2: 3290.38mV
Cell 3: 3279.31mV
Cell 4: 3280.84mV
4506.00
29.00
---
Cell 1: 3285.00mV
Cell 2: 3290.38mV
Cell 3: 3279.31mV
Cell 4: 3280.84mV
4504.00
28.00
---
Cell 1: 3285.00mV
Cell 2: 3290.38mV
Cell 3: 3279.31mV
Cell 4: 3280.84mV
4502.00
30.00
---
Cell 1: 3284.00mV
Cell 2: 3290.38mV
Cell 3: 3279.31mV
Cell 4: 3280.84mV
4500.00
29.00

Hello there I'm working on a similar project could you please share the code with us?

Thanks in advance.

 

[nurimu]

Hello everyone,
I started a project similar to this project. I am using BQ76PL455A-Q1 instead of BQ76PL534. I have difficulties in communication. I do the communication over UART but I cannot get cell voltages from BQ. How should I proceed?

 

[dmwahl]

Hello everyone,
I started a project similar to this project. I am using BQ76PL455A-Q1 instead of BQ76PL534. I have difficulties in communication. I do the communication over UART but I cannot get cell voltages from BQ. How should I proceed?

Here's my generic advice, I'm not too familiar with the part you mentioned although TI does seem to follow similar paths with their hardware. I'd suggest checking with TI for code examples, then hooking up a scope or logic analyzer to make sure your basic functions (read/write) are working. Once you've confirmed that your hardware interface is working, you can start building more complex functions and logic from there.

Despite the lack of activity here, I'm still working with this part although mostly in customized designs. I posted a basic set of code for the Arduino Uno that is confirmed to work on my own hardware. The code is rough to say the least, to the point where I'm torn about whether or not I even want to take credit for it.

https://github.com/dmwahl/BQ76PL536A-Arduino-Development-Shield/tree/master/sw/Arduino