Measuring converter output?

[Scott Forman]

After doing some reading and some wire chasing, I have determined that
my bus has a dual-output converter (Power Source 9180) with high or low
voltage set via a toggle switch. Unfortunately, though, I do not know
which setting is which on the switch. How do I determine what charge
is being delivered at the batteries at a given time?

Thanks
Scott Forman
82 FC35RB
Memphis