You need a certain amount of amperage per square inch to even being to have an effective reaction. 2 amps (off a trickle charger) is not going to do a very large part unless you let it sit a long time.
I've done just about every rust removal process on the net (media blast, molasses, electrolytic, phosphoric, grinder, pressure washer) and the overall best way is good old fashioned black beauty 40/80 grit and a pressure pot or siphon blaster.
Nothing else is as quick and easy. As long as you don't use sand, a good P-90 particle filter will suffice.
I'd like to meet the meathead that warps a panel with a properly set up sandblasting kit. I use 40psi and unless the rust is very, very deep it all comes off with no issues. Plus you can switch to walnut shells with the same rig and get the paint off if that's all you need.
Every other process requires a CLEAN unpainted part.. that's extra steps that if not done right, will cause you to repeat the process till you do get it right.
