A lead-acid battery that that has been insufficiently charged or has been left discharged during days or weeks will deteriorate due to sulfation. If caught in time, sulfation can sometimes be partially reversed by charging the battery with low current up to a higher voltage.
Recovery function for fully discharged batteries. Most reverse polarity protected chargers will not recognise, and therefore not recharge a battery which has been discharged to zero or nearly zero Volts. The Blue Power Charger however will attempt to rechargea fully discharged battery with low current and resume normal charging once sufficient voltage has developed across the battery terminals.