Komatsu 830E-AC, Shop Manual

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D02034 24 VDC Electric Supply System D2-3
24VDC ELECTRIC SUPPLY SYSTEM
ELECTRICAL SYSTEM DESCRIPTION
The truck uses a 24VDC electrical system which sup-
plies power for engine starting circuits and most non-
propulsion electrical components. The 24VDC
engine starting circuit is supplied by four heavy duty,
Type 8D, 12-volt storage batteries. Several compo-
nents require 12VDC and are supplied by circuits
tapped off the starting batteries.
The batteries are of the lead-acid type, each contain-
ing six 2-volt cells. With the engine off, power is sup-
plied by the batteries. During engine cranking, power
is supplied by the four engine cranking batteries only.
When the engine is running, power is supplied by a
high capacity alternator that is driven by the engine.
Lead-acid storage batteries contain sulfuric acid
which, if handled improperly, may cause serious
burns on skin or other serious injuries to person-
nel. Wear protective gloves, aprons and eye pro-
tection when handling and servicing lead-acid
storage batteries. See the precautions in Section
A of this manual to ensure proper handling of
batteries and accidents involving sulfuric acid.
During operation, the storage batteries function as an
electrochemical device that converts chemical
energy into the electrical energy that is required for
operating the accessories when the engine is off.
BATTERIES
Maintenance and Service
The electrolyte level of each cell should be checked
at the interval specified in Section P, Lubrication and
Service. Add water if necessary. The proper level to
maintain is 10 to 13 mm (3/8 to 1/2 in.) above the
plates. To ensure maximum battery life, use only dis-
tilled water or other types of water recommended by
the battery manufacturer. After adding water in freez-
ing weather, operate the engine for at least 30 min-
utes to thoroughly mix the electrolyte.
DO NOT SMOKE or allow flame around a dead
battery or during the recharging process. The
expelled gas from a dead cell is extremely explo-
sive.
Excessive consumption of water indicates leakage or
overcharging. Normal water usage for a unit operat-
ing eight hours per day is about 30 to 60 cm
3
(1 to 2
oz.) per cell per month. For heavy duty operation (24
hours per day), normal consumption should run
about 30 to 60 cm
3
(1 to 2 oz.) per cell per week. Any
appreciable increase over these figures should be
considered a danger signal.
Troubleshooting
Two most common problems that occur in the charg-
ing system are undercharging and overcharging of
the truck's batteries.
An undercharged battery is incapable of providing
sufficient power to the truck's electrical system.
Some possible causes for an undercharged battery
are:
• Sulfated battery plates
• Loose or corroded battery connections
• Defective wire in electrical system
• Loose alternator drive belt
• Defective alternator
Overcharging, which causes overheating, is first indi-
cated by excessive use of water. If allowed to con-
tinue, the cell covers will push up at the positive ends
and, in extreme cases, the battery container will
become distorted and cracked.
Leakage can be detected by continual wetness of the
battery or excessive corrosion of the terminals, bat-
tery carrier and surrounding area. (A slight amount of
corrosion is normal in lead-acid batteries). Inspect
the case, covers and sealing compound for holes,
cracks and other signs of leakage. Check the battery
hold down connections to ensure that the tension is
not great enough to crack the battery or loose
enough to allow vibration to open the seams. A leak-
ing battery must be replaced.