6 v GC batteries versus 12 v lithium deep cycle batteries

I got the (wrong?) idea the BMS cut off at 9.x (just below the depleted voltage of 10.0), was taken from the total voltage, so if un-balanced at 9.x total, one cell might be lower than one cell should be into cell damaging low voltage.

That could be wrong, so not meant to be bogus info, only a question up for clarification.