I had mine modded before it left the factory, to 49V, although the only time it has been activated, from memory I think it was a bit under 48V.
I'd suggest Vabsorb of 55V, and Vfloat 53.5V, and you'll need to work out your absorb time by watching net charging current, and it will depend on how fully charged you want to take the battery.
If you need to get the battery charged faster, then a higher Vabsorb will work better, but I wouldn't go over 56V for an extended period, particularly in summer.
Use a good quality multimeter to check your voltage set points, don't rely on the FM80's display.
Loomberah weather and astronomy including live solar radiation intensity and UV + Gunagulla aquaponics, organic eggs and cherries