Actually, batteries CAN be brought back to life.
One of my friends owns a remote property, that is electrically supplied off a battery and generator set. With the gen. set going, he has cooking and minimal heating, without the gen. set going, he has three four 240 volt lights only, for quite a practical time into the evening.
Has gas cooking as a backup, and campfire just for fun.
He picks up ANY 12 V battery, left on the side the road.
I do not know of the exact technique he uses but,
he empties the electroyte from the battery, and completely discharges and re charges them 2 or 3 times. All of them can be brought back to life, but the plates can be thinner, which makes them more prone to warping.
That is the reason why they should not be used in cars but,
as part of a set of a dozen or more batteries wired to produce 240 volts, they can be quite viable.
He has made a printed circuit for himself so that the voltage delivery is always close to 240 V.