I have some batteries which are used but not old, due to poor maintenance they don't keep a charge but they aren't short circuited.

Do anyone have a cure for that?

I was reading about frequency desulfators and adding Magnesium sulfate in the battery.

Thanks for any hint.

Mix ten heaping tablespoons of Epson salt in quart of very warm (not boiling) distilled water until totally dissolved.

Need to get about 2.5 oz per cell so may have to remove some electrolyte.

Rock battery back and forth to mix up. Charge overnight.

It only dissolves lead sulfate and causes it to drop to bottom of cell. The lead sulfate dissolved is no longer available to battery function.