Not sure you would call it a BMS as it stands. They are wireless modules made specifically for the Gen 4 Leaf battery module so one board has connections for the 4 cells of each battery module. It does top balancing to a couple of Amps max and I was given the source firmware to the MSP430 driving the boards so I can set the balance threshold voltage. Each module gets a Vehicle ID and a Module ID which is messaged to the head unit which displays the information. Unfortunately I don’t ahve the source for the head unit but it does display Max and Min battery cell voltages on the first display. Sub displays show battery voltages per module, icons displaying color to show voltage varisations, showing temp variations and showing what cells are being balanced if there are any.
A pic of the module is on this thread post: Nissan Leaf Gen 4 battery conversion - #3 by dougl
The developer used this system on an EV he used to race and was suposed to be coming up with a new head unit and updated battery modules with more accurate ADC’s and better wireless connectivitiy/noise handling. But I’ve not heard from him since Covid stuff started in early 2020.
It’s nice that each each battery module only has 6 wires( 4 cells ) and they are on a connector harness with ring lugs so easy to remove. I"ve designed a 3D printed case for the BMS module which mounts on each battery module.