A fully charged battery should read 13+volts right after charged. But after 12-24 hrs it supposed to settle down to 12.7-12.8 volts. I have 2 Exide Nautilus Marine DC27HDT bats from Rural King, 1 is 10 mths old the other is 1 mo old. Is there any reason they still read 13.04v after 48 hours, will this damage them. Or do I have a bad charger that's overcharging them, it does shut off when they reach 13.2v.