I must be missing something then, because at 13.5 or as you say 13.6 = 54.4v for sla's charged,
and lipo 13"s charged (4.2v) would be 54.6, that's pretty even.
3x5's fully charged (4.2) would be 65v, discharging down to 3.0 volts 45.v (to be safe) would not work with my controller,
one, because...