Help with setting up and using DC120100C SOC battery monitor

i don't think you need to calibrate the voltage, mine reads very close to my DMM

voltage versus SOC is an indicator of battery 'condition'
noting what is is when new, and what it is later, gives you an idea of how the battery is aging, aka holding up
saying comparing Volts at 80% soc now
and then again a few months from now or next spring etc..

i watch volts when charging against how many amps the batteries are taking at 'that voltage' against the SOC ampHr count

'trends and tendencies' as Mexi is always saying