​RE: Separators Only See Voltage
Yes, that is correct.  And that is why there is a question as to whether a
'two way' separator is right to use with a solar setup.  Even though the
solar may have reached the voltage level on the aux battery that allows the
separator to trigger and start charging the engine battery that does not
mean that the aux battery is fully charged, it only means that the aux
battery is charged enough that we see the 13.3 v level.