The manufacture of reliable, high-performance lead-acid batteries for use in demanding automotive, marine and industrial applications poses significant challenges in the arena of resistance welding. The central issue involves welding together a series of lead castings, called “tombstones”, which constitute the cores of the individual battery cells. These lead tombstones must be linked together using consistent and precisely controlled weld nuggets in order to assure proper operation and long-life of the final battery assembly.

Unfortunately, the intrinsic properties of the lead castings present a high level of variability that makes it very difficult to achieve consistent results with traditional AC resistance welding processes, which are also susceptible to current spikes and inherent variability in the welding process. Even the use of advanced AC weld controls, with more consistent secondary current output, is not enough to completely overcome the dynamic variability of the lead castings, requiring production floor operators to constantly tweak the weld parameters in order to maintain marginally acceptable consistency.