Mav,
I agree the "new" plates are junk! They dont even make a desent sinker or jighead.
This is the reason I said "some batteries" as I've seen plates out of older batteries that look very similar to the pix. Sailboat balast are usually thicker but the holes made me think that they could be used to layer the balast to adjust the weight.
Mntman, I've used plenty of roofing sheeting lead over the years and those plates just look too thick to be used for that purpose.
BTW,toetag I hope you're using a proper mask even if you're doing the smelting outside! Lead can and will accumulate in the body and there is no cure! I used to work grinding lead joints on cars,ya back then, we wore complete enviro suits with piped in air,my lead count went up 2 ppm and I asked to be removed from the job and they had no recourse but to move me as there are no safe limits to the amount of lead in the body.
I'd advise not just a mask but also proper clothing,a cheap hazmat/painters suit,tape the arms and legs,wear a headcovering and completely remove all the clothng before entering your house,this is really important if you have children about!! You just cant be too careful when working with lead IMHO.
