Voltage is a tricky indicator of charge level because the batts must rest for awhile after charging to read the true level via a voltmeter. After a few hrs rest 12.7 volts is a full battery.
A typical WFCO converter/charger will never get your batts up to full charge unless you are plugged into shore power for days and days. I get around that by using a stand alone 65 amp Boondocker charger run off my gen and hooked to the batts with jumper cables. 45 minutes in the morning and then solar the rest of the day works well to get the batts full.
Before adding solar, I would run the gen 3-ish hrs a day to get the batts to about 95% charge.
True deep-cycle batts like you have can take quite awhile in the absorption stage to to get to full. Very few stock converters are programmed to hold proper absorption voltage long enough to do the job.
