If it takes a long time to run down the battery, that is a long time while the battery is not fully charged so it will sulfate and lose capacity.
One of the hazards of solar is you can end up treading water somewhere above 50% SOC and below Full for weeks. Sulfation!
You must recharge to 100% SOC every so often. "Depends" how often.
The Trimetric instruction manual says at least once a week for Wets.
IMO it depends a lot on whether you do shallow cycles and get almost to full every day or whether you do a series of 50-90s in a row. Seems your SG goes deep in the red after a few 50-90s in a row especially if takes a few days to get down from 90 to 50.
Not so bad as that on solar doing 85-97s where you get to 97 every day. You still have to get to 100 every so often but not as often.
