I've just got the Multi RS set up, together with 3 x 100AH 48V batteries in parallel that are connected directly to the MultiRS, with no other charger or load.
The battery settings (provided by battery manufacturer) is:
Absorption voltage 58.4V
Float 56V.
Low voltage cut of 50V
After charging for a while I'm still only at 61% but the Multi went to Float.
It initially showed ~58V while in Float, but as soon as I turn on some load it went back down to 53.4V.
If I turn of the charger the batteries shows they are 53.3V.