ELECTRICAL STARTING SYSTEM
The electrical system on the engine generally consists
of a battery-charging alternator, a starting motor,
voltage regulator, storage battery, starter switch and the
The lead-acid storage battery is an electrochemical
necessary wiring. Additional electrical equipment may
device for converting chemical energy into electrical
be installed on the engine unit at the option of the
The battery has three major functions:
1. It provides a source of electrical power for starting
2. It acts as a stabilizer to the voltage in the electrical
The starting motor has a Sprag overrunning clutch.
3. It can, for a limited time, furnish current when the
Pressing the starting switch engages the starting motor
electrical demands of the unit exceed the output of the
pinion with the teeth of the flywheel ring gear and
energizes the starting motor. The starting motor drives
the pinion and rotates the crankshaft. When the engine
The battery is a perishable item which requires periodic
begins to operate, the Sprag clutch permits the pinion to
servicing. A properly cared for battery will give long and
overrun on its shaft, until the starting switch is released,
and prevents overspeeding the starting motor.
1. Check the level of the electrolyte regularly. Add
water if necessary, but do not overfill. Overfilling can
cause poor performance or early failure.
2. Keep the top of the battery clean. When necessary,
wash with a baking soda solution and rinse with fresh
To start the engine, a switch is used to energize the
water. Do not allow the soda solution to enter the cells.
starting motor. Release the switch immediately after the
3. Inspect the cables, clamps and hold-down bracket
regularly. Clean and re-apply a light coating of grease
when needed. Replace corroded, damaged parts.
4. Use the standard, quick in-the-unit battery test as the
regular service test to check battery condition.
5. Check the electrical system if the battery becomes
The battery-charging alternator provides the electrical
current required to maintain the storage battery in a
If the engine is to be stored for more than 30 days,
charged condition and to supply sufficient current to
remove the battery. The battery should be stored in a
carry any other electrical load requirements up to the
cool, dry place. Keep the battery fully charged and
check the level of the electrolyte regularly.
The Lubrication and Preventive Maintenance section of
this manual covers the servicing of the starting motor
A voltage regulator is introduced into the electrical
Consult an authorized Detroit Diesel Allison Service
system to regulate the voltage and current output of the
Outlet for information regarding the electrical system.
battery-charging alternator and to maintain a fully
charged storage battery.