Thanks Moshe for your informative reply. It is of great help.
Where do you control the amps in Method 1 – Conventional DC charging with VARIAC and bridge rectifier? And where are you using the three pronger plug? Do you mean the wires connected to the bridge rectifier diode?
Would you use, depending on the output voltage, an automatic amps fuse, for example 3 amps? to control the amps you want.