One key is the small generator. Can't ask it to do more than its maximum. With smaller chargers versus time it is important that the charger not even blink as it passes a normal 14.4 absorbsion setpoint and heads up to the theroretical optimum 14.8 volt setpoint. But if it takes a long time getting to say 14.6 the total energy replaced may equal a near fully charged battery. If the generator was a 2000 watt and the charger was 75-amps the time quandary minimizes. Imagine 14.0 volts present for two full days. See what I mean?
A charger that snickers at say 14.4 volts for a limited time would be an objective worth looking for.