Battery desulphators

EDTA treatment will work on a subset of batteries that happen to be a bit sulphated and will respond to the treatment. The very odd time, the tabs will work, but it's mostly a last-ditch attempt and fairly futile. The proper EDTA treatment involves draining the battery, putting in EDTA, flushing it out and re-aciding it properly; easy enough done, but slightly hazardous.

Electronic de-sulphators also work on a subset of batteries that will benefit from them. Sometimes they don't work at all. I have one that's dragged a couple of batteries back from the brink and got several months useful life out of them. Again, not something to be relied on, but works sometimes.

I was thinking of the electronic method (should have made that clear).

I emptied one, rinsed with deionised water, and then filled with Battery acid .... left it on long low charge ... and it seemed all OK afterwards. I'm sure it didn't get it back to 100% capacity but certainly usable.

I used to see tablets to pop into battery - but no idea if they are any good.