[mwebb]

..."
I have a charging system toggle switch, and my ABS computer is the first thing to fail as the voltage drops. This happens around 9V, "....

because there are so many variables and '
"it depends" scenarios that are possible

i can not say for sure -
but on the European cars that i work on - if you suspect a charging system problem that may be intermittent , you can look in the

AIRBAG system first ,

if there is a "system voltage low" DTC you know there is a charging system problem , you just need to dig a bit harder to find / prove it .

does that mean the AIRBG system stops functioning sooner ....
at a "higher voltage" than ABS or Ignition ?

because there are so many variables and
"it depends" scenarios that are possible ,
i dunno .

but it is something to consider , if you like having AIRBAGs when you need them.