I don't know technically how any of the desulfate cycles work. If anyone knows, I'd love to hear how it works.
Apparently some desulfators are different than others. For the last 15 years we've used BatteryMINDer type chargers just because they were the first I saw with a desulfate cycle & because it has worked for us.
Plus the charger has an optional high amp output powerful enough to charge a large 12 volt overnight. On our place we maintain about 18 large AGM batteries plus some spares, and replace two or three per year.
BatteryMINDer claims that they originated the desulfate cycle and that theirs is different enough to rate a patent. Whether that is true or not I have no idea. I've not looked up their patent and studied it so have no real knowledge what it does.
I do know from experience that if a battery is clear flat, it needs at least some charge from an old style "dumb" charger before the BatteryMINDer will take over and desulfate/charge it. But once it does, some of the "dead" batteries will actually charge up and hold a charge - so their desulfate must be doing something useful.
Interesting subject,
rScotty