Magnum inverter/charger and MPPT

stevene

Hello all!
I am new to this forum but much involved with solar power for many years.  I have a technical situation which I think I know the answer but maybe not.
I have lived full time in a motorhome for the last three years.  The motorhome was new and came with a 100W PV panel and controller that I immediately discarded.  The motorhome also came equipped with 400A of AGM batteries and a Magnum MS2012. I upgraded the Magnum with a ME-ARC50 and a BMK.  I also installed 760W of Grape Solar PV panels and a Blue Sky 3000i with a slave unit.  Everything worked great.
I am connected about 95% of the time to shore power.  During that time, the Magnum charger and MPPT controller work together.  The Magnum will go into a fully charged mode and allow the PV source to maintain the float.  However, it ocurred to me there was a better way to capture more solar power.  To make this story short, I installed a PLC with a small touch screen panel that figures out if enough solar is available and proceeds to shut off the 120VAC to the Magnum.  This causes the inverter to kick in and the motorhome relies on the solar to keep the batteries energized.  I turn the inverter back on when SOC hits 90% or solar power drops off.  The system has run this way for about a year now and it works surprisingly well.  It only ocassionally shuts off due to low SOC and usually because wife and/or grandkids go nuts with the hair dryers.  Also and as a result, I have drastically reduced my power bill in RV parks.
The Magnum is set at 14.5VDC for absorb and 13.5VDC for float.  The Blue Sky is set at 14.6VDC for absorb and 13.7 for float.
The technical issue is in the morning when solar wakes up or doesn't.  My guess: During the evening with no solar, the Magnum senses that no alternate source is present so impresses the proper float voltage on the batteries.  In the morning, when the sun rises, the MPPT has sensed that the batteries are floating so it stays inactive and produces no power.  I have programmed a 'test' routine into the PLC that on the half hour and hour setting during the morning hours with no power from the MPPT, it turns off the power to the Magnum and forces the inverter on.  The amperage on the Blue Sky will usually jump up to at least minimum amps and now takes over charging.  It will continue to run all day as expected.  Of course, when I am off the grid, this doesn't happen since there is no charger source from the Magnum.  
Does anyone perhaps see a flaw in my logic or can offer an alternative explanation?

Steven E Braun