FWIW.
To test your batteries using OCV, here is a chart, possibly from a link posted by Mark (an earlier save). Note that the battery must have been at "rest" for 8 (eight) hours before making this measurement.
If a LA battery including AGMs, sit for long periods in a state of discharge, they will never be able to put out 100% capacity, amp-hours, that is and the only way to test AH capacity is to run them down with a fixed load and measure the time it takes to reach 11 (eleven) volts, which would be close to zero % charge.
Charging the batteries at a higher than normal voltage will permanently damage them by boiling off electrolyte, which you can't replace in a sealed battery...
I don't have a lot of experience with AGM type batteries, but have run down and ruined several vented type lead acid types by using them for my inverters. I now use NiCd (air craft) types for my 120VAC inverter(s).