A123 UPDATE

These welders have many variables and depending on the size cables, probes and capacitors you used etc. will determine your weld settings. I have done hundreds of welds on A123 batteries and determined that they are no different from any other batteries. When your tabs are too thick to make decent welds, you have to improvise. Current always takes the easiest path and by making dimples and a cut in the middle (picture below) on the tab you are welding will force the current into one dimple, through the battery and out the other dimple. Concentrating the heat on the dimples and produce very strong welds.

You can punch your own dimples and use two pieces of nickel like the picture below.

 The probes are also very important, don't use probes with  flat tips unless you have a weld head that pushes the probes perfectly flat on the piece that gets welded. Make your tips round on a lathe with a file, like the microscope pictures of my probes below and then use very fine sanding paper to smooth the tips. Rounded tips will make perfect welds every time, won't stick and you can hold the probes at almost any angle.