Many desulfators you can buy or find on EBAY deliver only a handful of peak Amps and very low overall average power, in fact many of them suck power from the battery while pulsing and you end up with a discharged battery in worse shape unless you have a charger attached. Thus pulse charging solves a number of issues at once. Battery charging, desulfating & dendrite destruction.
Now the key to the removal of sulfate and destruction of dendrites or 'mossing' is significant power delivery and elevation of the cells' voltage to equalization levels. This also gasses the battery and removes electrolyte stratification, desulfating without gassing is going to take a very long time, if ever.
The limit on this is cell temperature as heat is generated by forcing current through the resistive sulfate and the low concentration of electrolyte. Battery temperature should not exceed 50°C.
The pulse delivery circuit in this project will deliver RMS average up to perhaps 10A and perhaps up to 1000 pulse amps with adequate heat sinking and forced air cooling.
This requires a decent DC supply of 36V @ 11A or 400W, many 'MeanWell' types are available on EBAY. I use 8.8A, 36VDC supply or better and limit power delivery to about 7.5A max RMS as I run the system 24/7 with no a/c in the tropics.
Worthy of mention is reflex or pulsed negative charging as well, as this has proven to be effective on stubborn batteries with crystalline sulfate. I use it, however this output board doesn't offer it. That's a different circuit element, but you can achieve it easily with a switched 12V lamp load. What this achieves is a reduction of bubble nuclei which form on the plates during charging and thus improves the electrolyte to plate contact surface and hence overall charge efficiency ramps up.
On the matter of energy efficiency, battery impedance can range from a few milliohms when new to a couple K ohms when sulfated badly. Now efficient power transfer theory states that max. efficency takes place when the supply impedance is equal to the load. Well since large amounts of power move when the load is high (small battery impedance) the goal is to achieve a very low impedance pulse charging circuit, which this one does. Overall it's somewhere around 10 millohms when built properly mainly limited by the capacitor bank. A useful trend is the capacitors ESR drops as they heat so their operation improves when hot, limited of course to there spec. operating temps.
Until the next update.