Lead Acid Batteries - Charge and recondition
It is not completely clear if these recondition methods do help, however, the results have been good on several batteries which did not have serious internal problems (such as shorts, warped plates, very dead cells)
Criteria, open circuit voltage above 10.5 volts, charge current should start small (indicating sulfated cells).
Recondition batteries using Epsom Salts --- Battery desulfation
Epsom salts in batteries videos
Another set of opinions on epsom salts.
I don't believe this one at all, but.... I tried it and the battery never recovered.
Note: as one of the videos shows there is a feeling that the Epsom salts effects the positive plates, however, if you are just trying to get a bit more battery life, and it works, so much the better.
Take apart a battery and work on it.
Digital Battery analyzer from Harbor freight
Another analysis of this tool
How to make a battery
How to make a li battery
Recycle car battery