A lead acid battery is, most commonly, a 12 volt battery with a series of six cells. Each cell contains a positive lead oxide plate and a negative lead plate and is filled with a solution of sulphuric acid. As the battery discharges, the positive plate reacts with the sulphuric acid and produces lead ions in the water. The lead ions combine with the sulphate ions in the sulphuric acid to form lead sulphate. As the lead sulphate coats the plates, the battery is less effective and will eventually fail. Treating the battery with an acid called EDTA will remove the sulfating and prevent future sulfating.
Add a rounded teaspoon full of EDTA to each cell in your battery. This figure works for an average-sized battery, but it is not critical to get an exact amount.
Agitate the battery frequently for the next couple of days and use the vehicle regularly. Do not charge the battery completely during this time.
Charge the battery thoroughly after a couple of days. You should see increased performance from this point on, as the EDTA frees the plates of lead sulphate that has been coating the plates.
Treating the battery with EDTA is most effective when the battery spends long periods of time not fully charged, as there are more lead ions.