GMC 1976 ZEO 6083 Maintenance Manual page 384

6Y- 4 ENGINE ELECTRICAL
Figure 6-Internal View of Battery with Vent Wells
special vent plug down into each vent well . The seals
drop into the cells, and can remain there since they
are not chemically active and will cause no harm .
A wet charged battery contains fully charged ele-
ments which are filled with electrolyte before being
shipped from the factory. The flame arrestor type
filler/vent cap batteries can be wet or dry charged on
shipping . The maintenance-free battery, which has
no vent wells, is wet charged.
Figure 7-Vent Well Construction
THEORY OF OPERATION
The lead-acid battery or storage battery (figure 1)
is an electrochemical device for converting chemical
energy into electrical energy . It is not a storage tank
for electricity as is often believed, but instead, stores
electrical energy in chemical form .
Active materials within the battery react chemi-
cally to produce a flow of direct current whenever
lights, radio, cranking motor, or other current con
suming devices are connected to the battery terminal
posts. This current is produced by chemical reaction
between the active materials of the PLATES and
sulfuric acid of the ELECTROLYTE.
The battery performs three functions in automo-
tive applications :
1 . It supplies electrical energy for the cranking
motor and for the ignition system as the engine is
started.
2. It supplies current for the lights, radio, heater,
and other accessories when the electrical demands of
these devices exceed the output of the generator.
3. The battery acts as a voltage stabilizer in the
electrical system . Satisfactory operation of the vehi-
cle is impossible unless the battery performs each of
these functions .
The simplest unit of a lead-acid storage battery is
made up of two unlike materials, a positive plate and
a negative plate, kept apart by a porous separator .
This assembly is called an "ELEMENT" (figure 8) .
Figure 8-Battery Element