Our research work has been devoted to the identification of processes
that cause premature capacity loss (PCL) in lead/acid batteries. Atten
tion has been paid to the resistance of the active material and to the
resistance of the interphase between the active material and the lead
grid in specially prepared positive test electrodes, measured by an e
xact etc. method. Resistance measurements performed on electrodes with
grids from seven different lead alloys showed that PCL is related to
increasing resistance of the active material. In contrast, PCL in elec
trodes having pure-lead grids is caused by the formation of an insulat
ing layer on the grid surface, evidenced by the steeply rising interph
ase resistance.