TM 10-6140-200-14
These vertical rods become the conducting cores of a like
number of porous, tubular, glass or plastic retainers which
contain the active material. Each tube is sealed at the top
and bottom after filling to prevent the loss of active
material. A typical tubular positive plate is shown in
Figure 1-4.
Figure 1-4. Tubular type positive plate
Figure 1-5. Pasted type positive plate
(2) Pasted type. The grid of the pasted plate
consists of horizontal and vertical or diagonal cast lead
porous rubber or plastic, both of which are resistant to
conducting members within a rectangular cast frame. A
heat and acid. Separators provide mechanical and electri-
slurry of active material is pasted or squeezed into the
cal insulation between positive and negative plates but are
voids and the surfaces are then covered by porous glass
porous enough to permit passage of electrolyte. The
and plastic retainers to prevent the loss of active material.
grooved or ribbed side of the separator is placed toward
A typical pasted positive plate is shown in Figure 1-5.
the positive plate to allow a free flow of electrolyte to
the active material. The flat side faces the negative plate
f. Electrolyte. The element within the jar is immersed
to contain the sponge lead.
in an electrolyte, which is a solution of sulfuric acid and
"pure" water. This permits the necessary chemical reac-
h. Positive Plate Retainers. Tubular type plate retainers
tion to occur and provides a conducting medium in which
the flow of electric current takes place. The electrolyte in
are made from porous glass or plastic which is woven or
a fully charged cell normally has a specific gravity of
shaped into the form of a round or square tube. A plate
between 1.275 and 1.395 at 77 degrees F. As a cell
is composed of a number of such tubes which are filled
discharges, the specific gravity decreases. Measurement of
with active material in those areas surrounding the
this specific gravity. by means of a hydrometer, indicates
conducting cores of the grid. Pasted type plate retainers
the state of charge of a cell. To save time, in determining
are added after pasting, typically by wrapping the plate
this state of charge for the battery, a pilot cell or cells
first with fibrous type glass tape or mats and then by a
perforated plastic envelope complete with bottom boot or
may be chosen. This is a selected cell(s) whose condition
by other suitable filtering systems. All types of retainers
is assumed to be representative of the condition of the
act to prevent the escape of positive active material
entire battery.
during normal use. Retainers are not needed on negative
plates.
g. Separators. Separators are made from either micro-
Section IV. PRINCIPLES OF OPERATION
charge the electrical energy supplied by the charger causes
1-6. Fundamentals of Cycling
an electrochemical reaction within the battery. This
restores the active materials to a fully charged condition.
A cycle is a discharge followed by a charge. During the
1-4
