Solar Battery Charge Issue

Not sure where you came up with a depletion of 50% unless you are using it just as an example. 25% daily depletion rate would be a more accurate assessment from the next morning's voltage readings from a voltage meter prior to setting out my panels for the day. What is puzzling to me is that I would always reach Full/Float at 13.6 volts by midday in southwest Arizona according to the charge controller display... until just recently. I guess my charge controller must have been lying to me for the last 3 years and I did not know it. I just don't know.