I have designed them, several decades ago, for very heavy AH battery banks.

I am quite familiar with the present available desulfator sold in Internet which is a copy of a simple pulser ( LM555) with a 330 Uh choke with a 2200 microhenry choke to isolate the 330 uh choke pulse from the power supply for the pulser section.

They are available from 20 to 120 dollars and most of them have the same basic principle and it seems that they have not discovered the circuits for high power which implies to have a lot more of technical knowledge to make them.