The trend in car batteries is technology far beyond the heavy, fume-belching lead-acid behemoths we use today. Plus, lead batteries can't take the heat and voltage needed by hybrid and electric automobiles. And if you smelt a modern car battery you're engangering the whole neigborhood because it releases phosgene gas. The other danger is the calcium in battery plates forms an intermetallic bond with antimony in lead solution, which depletes the alloy of antimony during skimming, and the resulting calcium/antimony dross releases HIGHLY toxic gas fumes when it is exposed to atmospheric moisture, which starts to happen as soon as it cools below the dew point. Don't risk it.
As far as the Gov't agencies getting what lead I might possess, they can have it at the same time I turn in all of my guns
Gear