also a dc to ac rectifier is not like a check valve in which something runs in one direction and not the other, it can be hooked up either direction, in electrical work a check valve for electricity is called a volt trap, in which power can not feed back into a circuit, in which like a power house for teco , in which IF it feed back , it would back feed into there generators and short out there windings

also try useing some 6013 rods, I am sure you will find they will weld better for you,

hope all this helps or at least informational.