He took them apart and combined the pieces to make one good one. He sold this rebuilt battery back to the junk yard for fifty cents. He rebuilt batteries for several years until the acid burns on his arms became too painful. Reason prevailed over economics. Since generators and starters are copper wire and steel and no acid at all, he learned to repair them instead.
Generators present a particularly difficult problem for repair.
In the original manufacture, the set screw is turned in so tightly that to disassemble a generator, the screw must be hammered with force until it breaks free and can be turned out normally. Once, while beating on a particularly stubborn one, the screw head broke off, flew across the shop and struck one of the workers square in the eye. I remember that worker as an old man, with his one blind eye, still working in my Grandfather's shop. After the accident, he was assured a job for life and became one of Grandpa's best friends. Long after the shop had closed for the day, they'd sit in the back and talk in Armenian together.