The types and features of automotive lead–acid batteries
are shown in Table 1. The specifications for the battery have
been modified in accordance with the trend towards MF
batteries. For example, the grid alloy has been changed
progressively from an antimony alloy to a low-antimony
alloy, to a hybrid and, presently, to a calcium alloy in order to
reduce water losses during charging. The grid-manufacturing
process for calcium alloys has also been changed from
the conventional casting method to the expanding method.
With expanded grids, the positive active-material can fall out
more readily than with the cast-type. Thus, a pocket-type
separator is required