A discharged 6 volt battery is 5.8 volts at rest.
#DIY 500 SERIES POWER SUPPLY FULL#
After a full charge, if the battery is not going to be float charged, the at-rest voltage will slowly return to the nominal full-charge voltage. You may see it go as high as 16 volts when charging, depending upon the charger. A float charge (maintenance charge) for a 12 volt system is 13.5 to 13.8 volts active charging requires at least 14.1 volts.