Sorry the for necroresponse, but I've been meaning to discuss this for a while.
I went back and watched a portion of Prof. Kelly's video and noticed that the BECM seems to monitor in 6 groups of 16 cells. I overlaid the cells from each group on top of my graph and found something that might be interesting (not sure).
I'm not following how you got here? The BMS quite clearly has 12 balance chips, meaning 8 cells each (this is common). We can also see 8 transistors per chip, backing that up. If you're referring to the harness connectors, that's just convenience, not related to how the BMS works.
He did mention that each cell at the endpoints of each group of 6 are duplicated because you need a reference voltage to measure the cells in the next group (paraphrasing). I take that to mean that given all the wiring and internals, when the BECM monitors 1-16, it monitors 16-32 next and "compares" what "channel 1" saw for 16 and compares it to what "channel 2" saw for that same cell 16. The question then becomes, what if there is a small difference?
Ok that's not quite how it works - so when you measure voltage, you need a negative reference and a positive reference, and you're measuring the
potential difference between the two.
So we know that the chips work in groups of 8. It's not that chip 1 is measuring cell 8, and chip 2 is measuring cell 8, and comparing.
Chip one measures:
- ground to lead 1 - cell voltage 1
- lead 1 to lead 2 - cell voltage 2
...
- lead 6 to lead 7 - cell voltage 7
- lead 7 to lead 8 - cell voltage 8
Chip two measures:
- lead 8 to lead 9 - cell voltage 9
- lead 9 to lead 10 - cell voltage 10
...
- lead 14 to lead 15 - cell voltage 15
- lead 15 to lead 16 - cell voltage 16
Chip three measures:
- lead 16 to lead 17 - cell voltage 17
...
etc
you can see that you're always measuring the voltage between two cells. So an overlap in PCB routing is needed between the two adjacent chips of the cell voltage with multiple of 8 - but there's no need for the harness to have this.
Prof Kelley absolutely knows his stuff, but I'm quite confused about the BMS labels, leading me to believe that neither is correct. He says that both Volt and Bolt BMSes are identical, but has completely different labels on the connectors. I don't know if this was a mistake, and if so, it makes me wonder how much is assumed about the pinouts on
both of them.
Volt:
1-16
16-28
28-44
44-62
62-79
79-96
Bolt:
1-16
16-33
33-48
48-64
64-80
80-96
Either way it doesn't matter - the pinout of the wires has nothing to do with the monitoring of the cells.