Snake Oil!!!

No bad batteries are being "fixed", just poorly maintained and discharged batteries being cleaned and charged.

When I worked in auto parts years ago, I found that most people assumed that anything electrical wrong with their car was the battery's fault, so that was their first guess. We used to test core batteries with a load tester, then just charge the ones that passed and use them as store loaners. Not uncommon to find several a day.

These people are just taking advantage of most people's faulty troubleshooting skills, usually by the time the average car owner figures out that his problem wasn't the battery he has already replaced it, thus there are alot of serviceable batteries out there that just need some distilled water and a good trickle charge, no magic involved.