I pulled this from another forum. I haven't tried it myself but others who have says it works. Of course this is really intended for batteries with removable cell caps.

Hi guys. I tried the baking soda and vinegar hack on my battery, and I'm pretty sure it worked. It'* been running strong for over a week now. Here'* what I did. Used safety glasses and rubber gloves. Drained the battery in a plastic tub, then transfered to a plastic gallon jug for proper disposal. Poured 1\2 box of baking soda in the holes, then 3\4 cup of vinegar in each hole. Waited a few min, maybe 10. I could see small bits of black stuff foaming out. Then dumped it, it foamed again hard and a bunch of black grit came out. Did this 2x. Then rinsed with water 2x. Lead plates were shiny. Added new acid $20 at Battery Boy.

I though I would need to charge it back up, but to my surprise I heard my radio load a cd so I gave it a shot and it started. Is that normal? I thought it needed to be charged?

The guy at Battery Boy gave it a 50\50 chance at working and explained that what I was doing only worked on batteries that are internally undamaged and suffer extreme sulfurcation or something like that. Basically the black junk that was on the lead plates. Battery is 9yrs old.

Until you get the CCA we have no idea how well it worked.

I'm curious how this turns out over some time!

That would be the question. I haven't yet tried it but hope to.

To make it a true experiment you need to charge the old battery and check it'* CCA then do the restore and do the same thing. Have many more CCA do we have?
Do this on 1000 batteries and average the results. You got this.