Stupid Guestion
 

Ok, I know I'm ignorant when it comes to HHO generation, but I was thinking the other day about something that comes to mind, if you overcharge a battery, what happens, the battery caps blow off and the battery swells, so what causes this ?, my guess is it is producing Hydrogen and if that's the case, would it not be possible to empty the battery acid out of an old car battery and replace it with Distilled water and an electrolyte and turn the battery in to a Generator?. and as far as current is concerned, would a DC Capacitor not help reduce the the electrical load on the alternator ?.

Just a thought from a newby that knows nothing., wished I knew more, but just starting on this gas saving crusade.

Yes a battery is an electrolytic cell, lead may not be the best plate material for an HHO cell however (SS isn't really ideal, it's just convenient) so it may work only for a while. Other disadvantages are weight and size... the case design of smaller batteries might well be worth looking into for building an HHO cell into however, with replacement plates.