ELECTRICAL STARTING SYSTEM
The electrical system on the engine generally consists
of a battery-charging alternator, a starting motor,
The lead-acid storage battery is an electrochemical
voltage regulator, storage battery, starter switch and
device, for converting chemical energy into electrical
the necessary wiring. Additional electrical equipment
may be installed on the engine unit at the option of
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.
Pressing the starting switch engages the starting motor
3. It can, for a limited time rush current when the
pinion with the teeth of the flywheel ring gear and
electrical demands of the unexceed the output of the
energizes the starting motor. The starting motor drives
the pinion and rotates the crankshaft. When the
engine begins to operate, the Sprag clutch permits the
The battery is a perishable item which requires
pinion to overrun on its shaft, until the starting switch
periodic servicing. A properly cared for battery will
is released, and prevents overspeeding the starting
give long and trouble-free service.
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 engine starts.
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.
The battery-charging alternator provides the electrical
current required to maintain the storage battery in a
5. Check the electrical system if the battery becomes
charged condition and to supply sufficient current to
carry any other electrical load requirements up to the
If the engine is to be stored for more than 30 days,
rated capacity of the alternator.
remove the battery. The battery should be stored in a
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
system to regulate the voltage and current output of
the battery-charging alternator and to maintain a fully
Consult an authorized Detroit Diesel Allison Service
charged storage battery.
Outlet for information regarding the electrical system.