Not sure if you are getting the Volt and Percentage figures from the same monitor? Ours only shows volts FWIW, so I will comment on this side of the equation. Just one lay person's opinion.
After you charge your batteries, and wait one hour after unplugging shore power, the general rule of thumb is that your monitor should show 12.8 volts plus or minus. The batteries should then hold a charge above 12.5 for 2-3 days, assuming you do not use any 12-volt items.
When the batteries get down to 12.5 volts, they are still holding about 90% charge. When they get down to 12 volts or so, they are then at 50% and you start to do serious damage to them if you use them further without charging. We always try to keep ours above 12.5 volts, as we have a quiet Yamaha tri-fuel 1000 watt generator, which is easy to hook up and run without disturbing the neighbors.
I am on the road right now, but will post reference material and a chart when I get home in an hour or two.
PS edit -- have not read your other thread yet, but for every one's information: