Chapter 10 Ignition Systems
203
with the electrolyte in them, ready for use if the
charge has been kept up. Dry-charged batteries
must have electrolyte installed after purchase.
Both types of batteries function in the same way.
Battery Construction
The typical 12V battery is constructed with a
hard rubber case and six separate compartments
called cells. See Figure 10-24. There are a specifi c
through such a great number of conductors in the
secondary, a very high voltage is developed. The
amperage, however, is proportionately low. This is
a typical characteristic of any transformer.
Laminated iron is used as the center core of
the coil. It also forms the outer shell of the inner
assembly, providing maximum concentration of
the magnetic fi eld. The inner assembly is sealed in
a coil case, and the remaining space inside is fi lled
with a special oil to minimize the effects of heat,
moisture, and vibration.
The top of the coil is provided with two pri-
mary terminals. They are marked positive (+) and
negative (–). The positive terminal must be con-
nected to the positive side of the battery. The nega-
tive terminal connects to the switching device. The
center tower of the coil contains the high-tension
terminal.
Lead-Acid Battery
The battery is the sole source of energy for the
battery ignition system of a small gasoline engine. A
generator is used to replenish energy in the battery.
However, the generator does not supply energy
directly to the ignition system.
Lead-acid type batteries are used in battery
ignition systems. The cell plates are made of lead,
and a sulfuric acid and water solution serves as
the electrolyte. Wet-charged or dry-charged types
are available. Wet-charged batteries are supplied
Kohler Co.
Figure 10-23.
The switching device opens and the field collapses, inducing high voltage in the secondary windings of the coil.
Primary Circuit
Secondary Circuit
Magnetic Field Collapsing
Ignition
switch
Ignition
coil
High voltage
induced in
secondary
windings
Ground
Spark plug
Switch
device open
High-tension lead
Battery
Deere & Co.
Figure 10-24.
A battery provides all the current for a battery ignition
system. A 12V battery has six cells, each producing
approximately 2V.
Cell connector Cell cover Terminal
Plate
Sediment chamber
Plate strap
Bridge
Hard rubber
case
Copyright Goodheart-Willcox Co., Inc.