Charging a battery with float voltage
Yes, it is possible but it takes a lot of time, first your battery will be charged at the constant current until the folat voltage (13.2) is reached (75%) then it will take a lot of time to charge the 25% (low current).
The best way to charge your battery is the 3-stages charging it like the float charging and continues to charge until your BOOST voltage (14.4V), then the current is reduced to 1/4 of the maximum to the 90% then the 10% are charged slowly by the float charging.