Battery Desulfator Circuit

Absorption is what you want, is time consuming, it is named because a chemical reaction is taking place and gradually depleting (or absorbing) the last remaining lead sulfate (some is even in solution). Absorption is important in lead-acid because the lead sulfide can deposit in places that prevent it from providing power storage (sulfation). When all the lead is converted into its metallic form the electrolyte can dissolve some of the sulfation, and reverse the damage, but this is tricky business, of cycling gassing and absorption voltages without allowing the cell to run out of water or build up to much pressure.