Having thought about this some more, I’m not yet sure if isolating each cell like this will actually work for automatically recharging a cell that is bypassed by this circuit.
Also, I’ve found some additional complications that happen when the majority of cells are missing: if LPC loses power, but there is still enough voltage coming from 4 batteries (in a scenario where 4 batteries are dead), the 5V and 3V3 rails turn on by themselves.
While tracking down this problem I found a solution to implement a pretty proper UVLO on the motherboard with these patches (requiring 4 resistors in total):
I’m dogfooding this patch in my personal Reform over the next days and will report back.
Edit: Reuploaded the LPC UVLO drawing, 68k resistor was in the wrong place.
Edit 2: The previous idea of pulling down the ON/~OFF on the bucks doesn’t actually work because then the FETs cannot override this drain and the bucks will not enable (i.e. you can’t turn the system on). This is my next idea to ensure that the bucks don’t turn on if LPC_VCC has shut down: (remembering to remove R88 and R89):
