Repurpose to rust remover ? Check.
Continue using charging batteries ? Negative. Ditch and upgrade to modern computer-chip staged/auto charging models. I bought a new modern automatic model, COULDN'T BE HAPPIER with the new technology charger, it's really amazing how they work, and much better for the battery in achieving 100% charge WITHOUT damage, completely eliminating even minor damage.
I had an old Craftsman like those above, was forced to replace it after it had completely corroded inside and out during a particularly wet (super high humidity) summer in my garage. I since then installed a dehumidifier, something for another thread.
Anyway I agree, I LOVED that old charger, fantastic build quality for what it was at that time. But you just can't beat a modern computer-controlled charger, you just can't.
Sorry for the bad news.