BMS Readout Redesign 4

I received the new PCB and built up one assembly with the I2C driver ICs that were described in the Blog below, BMS Readout Redesign 3.  The PCA worked to read the RTC and SD card but failed to initialize the Rotary Encoders and the LCD did not show any text.  After some checking I remembered that I had swapped the I2C lines in the PCB design to make the layout better with less crossing of data lines going to the screw terminals, but did not update the silkscreen text for each pin.  Once I swapped the wires for the I2C data lines everything worked!  The I2C line drivers did the job.  The 7-segment display, that was being driven by the MOSFET logic level shifter also worked.

Below is an image of the New PCA, showing the I2C driver ICs (U2,U4,U8) and the MOSFET (Q1) logic level shifter circuit. I made the PCB a different color to tell the different versions apart. 

I connected everything in the enclosure and ran the 9 BMS simulation test program.  It worked perfectly.  Now I can think about deploying the reader in the car.

Below is an image of the BMS simulation test bench setup. The BMS PCA on the right is connected to a barrier strip with a series of resisters.  The circuit simulates ten battery cell voltages.  It is connected to the reader via the CAN BUS wires (blue-white).  I developed this test method over a year and a half ago to test the BMS PCA (link).

Link to BMS Reader Redesign 3.