(06-05-2020, 05:04 AM)TWIH Wrote: The weakened lead post broke off, rendering the new battery now just functional for a core. Unfortunately it couldn’t take the “straightening” up strain.
Lead is easily drilled, and you can use a tapered point sheet metal or even wood screw or a tap to cut coarse, not fine machine threads. I've done this more than once when I decided that I did not want to waste a ring terminal that was too small to fit the threaded stud of a flooded marine battery. I just put some tape on the drill bit to know how deeply I was drilling and use a screw of appropriate diameter and depth to hold the ring terminal to the lead post.
I am not sure how much depth you have to work with, but since you are not starting engines with it, the screw need not go in very far. Just don't think you can remove and return screw dozens of times, two to three max before having to step up the screw's diameter, and don't overtighten as lead is soft and easily stripped.
Will probably have to file a flat spot to get good surface area for a ring terminal.
you could also sort of make a bussbar and secure it to the terminal with two smaller screws and perhaps even some sort of glue/epoxy, to take some load off the screws, and then attach ring terminals to the bussbar.
Unless the lead terminal broke off well below the red or black epoxy they sealed around it, that battery is not just a core charge.