According to the marketing material from BatteryMINDer, the charger first attempts to take the battery to 14.2 volts. Then it switches into a desulfate/maintenance (D/M) mode. If, after a few days, the charger does not get the battery to 14.2 volts, there is a button to put the charger into D/M mode which is supposed to apply a 'certain frequency' intended to remove the sulfation. If, after a week or two, the battery cannot reach 14.2 volts, it is probably beyond recovery.
So much for marketing. My actual experience has been pretty much as described above. I hooked the unit up to a known good battery and attached a DVM to observe the claims. Sure enough, the meter slowly climbed to 14.2 volts in charge mode and then dropped down to 13.6 volts (D/M mode). Then I tried a 'questionable' battery and after 3 days, the DVM could not register higher than 13.75 volts in charge mode and would not automatically enter into the D/M mode. Over a period of a week, I manually alternated between 'charge' and D/M. Last check showed the voltage to be up to 14.12, not enough to automatically enter D/M mode. I intend to leave it in D/M mode for a week and then switch to 'charge' to see if it reaches 14.2 volts.
These are my observations. For that which is going on inside the battery concerning desulfation, I cannot give testimony.