Navy,
You are correct, and I meant to say the "absorption" voltage needs to be 13.8 to 14.5 volts as seen in the description and graph below. The real key to "float" is to keep the current into the battery at less than 1% of battery capacity to limit electrolyte loss... Your voltage ranges quoted above are very good examples of the voltages involved in the various stages.
Note also that the bulk stage on two stage chargers ends at the higher voltage of the absorption/equalization range of 13.8 to 14 volts for flooded lead acid cells and sealed lead acid types (red and green traces on the chart...) Some older RV chargers are two stage units.
Bulk
The Bulk stage is where the battery receives the majority of its energy, making up about 80% of the recharge cycle. During this stage the Battery is given as much current as possible while keeping the battery temperature under 100° F.
Absorption
A 3 Stage Controller adds an Absorption phase (Sometimes called an “Equalization Stage”) that other “Smart Chargers” don’t include. During this stage the controller will maintain the target charging Voltage (Between 14.1VDC and 14.8VDC), while decreasing the charging Amperage. This helps retain the energy stored during the Bulk stage.
Float
Keeping a battery topped off once it is fully charged is a big part of getting the most out of SLA Batteries. The Float stage does exactly that by reducing the input Voltage to between 13VDC and 13.8VDC, and the Current to less than 1% of the Battery Capacity. This will keep a battery fully charged indefinitely.
Thanks for correcting my earlier terminology error!
Chuck