A method of applying pulsation energy to an online battery backup system including the steps of (1) sampling at least one voltage sampling circuit to monitor a float voltage drop across the terminals of each battery unit within a plurality of battery units; (2) selecting from among the plurality of battery units the unit having the greatest float voltage drop; (3) operating a pulse generation circuit to apply pulsation energy across the terminals of only the selected battery unit; and (4) ceasing to operate the pulse generation circuit in response to a predetermined trigger. A generally corresponding method may be performed on each battery cell within the plurality of battery units. Also, battery pulsation systems for an online battery backup system including means for applying pulsation energy across the terminals of only a selected battery unit or a selected battery cell.