Assuming a hands-off setup with just an scc, set your CV voltage to no more than 13.6v.
LFP cells will not fully charge at 3.4v per cell or lower. Anything higher and they *WILL* fully charge to full capacity eventually. It happens faster at higher voltages, and much slower at lower ones, like 3.45v per cell.
It's a knife-edge setting, so generally 13.6v (3.4v / cell) - while actually charging - is the highest you'd want to go to prevent them from slowly absorbing to full capacity. That's approx 80% capacity.
If you are using a system with a bms that has balancing, I'd charge to 100% with higher voltages at least once to attempt to smooth out any *small* differences in balance. Then change your CV to the lower voltage to limit the charge to 80% with your normal operation.