Every time I observe my meter on mine I never see anything above 13.6v. I have solar that keeps my batteries to 14.7v every day.
It might be that you manually boost the batteries and the unit only goes in boost momentarily once in a while.
I figure its why my batteries never charged properly with my power plant.
Barbara and Laurent, Hartland Big Country 3500RL. 39 ft long and 15500 GVW.
2005 Ford F250 SD, XL F250 4x4, Long Box, 6.0L Diesel, 6 Speed Stick, Hypertech Max Energy for Fuel mileage of 21 MPusG empty, 12.6 MPusG pulling the BC. ScangaugeII for display..