I'm not really seeing that condition
Generally we use one of the generators everyday,
And then the solar covers part or all of the day time power requirements
I generally get at least one day a week of long runtime for a full charge or dang near like 99%
Full
I'm not doing 40-80,
I'm sure there have times when I ran an extra charge day in week, because the bates seemed a little low or my pc use was heavier
I think I've managed to prevent most of any progressive sulphation
Also it should be noted these batteries have a pulse desulphator attached to them that is automatically on, when ever there is a charging voltage present from any source,
Hopefully this has played some role in keeping them in shape