ribed in the preceding paragraph.

3. Charging Sulphated Plates at too High a Rate. In sulphated plates,
the chemical actions which take place as a battery is charged can
proceed but very slowly, because the sulphate, besides being a poor
conductor, has formed larger crystals which present only a small
surface for the electrolyte to act upon, and has also covered up much
of the remaining active material. Since the chemical actions take
place slowly, the charging current must be kept at a low value. If too
heavy a charging current is used, the battery will be overheated, and
some of the current will simply cause gassing as explained in No. 2
above. The gas bubbles will break off pieces of the sulphate, which
then fall to the bottom of the jars as "mud."

4. Charging Only a Part of the Plate. If the electrolyte falls below
the tops of the plates, and the usual charging current is sent into
the battery, the current will be too great for the plate area through
which it passes, and hence gassing and shedding will result as already
explained.

The same condition exists in a battery in which one or more plates
have been broken from the strap, either because of mechanical
vibration or because of impurities such as acetic acid in improperly
treated separators. The remaining plates are called upon to do more
work, and carry the entire charging current. Gassing and shedding will
result.

5. Freezing. If a battery is given any care whatever, there is little
danger of freezing. The electrolyte of a fully charged battery with a
specific gravity of 1.280 freezes at about 92 deg. below zero. With a
specific gravity of 1.150, the electrolyte freezes at about 5 deg. above
zero. A frozen battery therefore indicates gross neglect.

As the electrolyte freezes, the water of the electrolyte expands.
Since there is electrolyte in all the inner parts of the plate, the
expansion as the water in the paste freezes forces the pastes out of
the grids. The expansion also cracks the rubber jars, and sometimes
bulges out the ends of the battery case.

Loose Active Material

This refers to a condition in which the active materials are no longer
in contact with the grid. Corrosion, or sulphation, of the grids
themselves is generally present at the same time, since the chemical
actions are shifted from the active material to the grids themselves.

1. Over discharge. As a battery discharges, the lead sulphate which
forms causes an expansion o