Would you soak your feet in hydrachloric acid to relax? This is the kind of thing that I've heard that epson salts are used for.

http://www.care2.com/greenliving/use-epsom-salts-13-wonderful-ways.html

(I must admit I've never used them -- I've used a salt solution as an antibiotic and "cleaning" treatment, in a pinch.)

AND...

If you could get by with using a "harmless" salt solution -- why would your risk putting that "harmful" acid in you batteries? If that were the cause "Cosi Fan Tutti" (they'd all be doing it...)

I do agree that you could generate a charge with a salt solution and lead cells -- but I don't have any faith that it would be as effective as a real "acid" solution.