Common Causes Of Battery Failure; Troubleshooting; Battery Voltage Warning" Pictogram; Voltage Gauge Definitions - PREVOST H3-41 Maintenance Manual

SECTION 06: ELECTRICAL
as prescribed. Refer to torque tables at the
beginning of this section.
Replace protective caps to prevent corrosion
and sparks.
9.13 COMMON CAUSES
FAILURE
When a battery fails, the cause of failure may be
related to something other than the battery. For
this reason, when a battery failure occurs, do not
be satisfied with merely recharging or replacing
the battery. Locate and correct the cause of the
failure to prevent recurrence. Some common
external causes of battery failure are as follows:
1. A defect in charging system such as high
resistance or a faulty alternator or regulator.
The dashboard ALTERNATOR telltale light
illuminates if one of the alternators is
defective.
ALTERNATOR telltale
2. A malfunction within the 12-volt system
(equalizer).
3. Overloads caused by a defective starter or
excessive use of accessories.
4. Dirt and electrolyte on top of the batteries
causing a constant drain.
5. Hardened battery plates, due to battery
being in a low state of charge over a long
period of time.
6. Shorted cells, loss of active material from
plates.
7. Driving conditions or requirements under
which the vehicle is driven for short periods
of time.
8. A constant drain caused by a shorted circuit
such as an exposed wire or water infiltration
in junction boxes causing ground fault.
9. Extended operation of preheating system
with engine not running.
10. Failing to close disconnect switches during
the night.
70 PA1621 Maintenance Manual All Series | Revised Sept 2019
OF BATTERY

9.14 TROUBLESHOOTING

If a battery is known to be good and then has
not performed satisfactorily in service for no
apparent reason, the following factors may
reveal the cause of trouble:
1. Vehicle accessories
switches inadvertently left on overnight.
2. Defects in the charging system, such as
high wiring resistance, faulty alternator,
regulator or battery equalizer.
3. A vehicle electrical load exceeding the
alternator (or battery equalizer) capacity,
with the addition of electrical devices, such
as CB radio equipment, a cellular phone or
additional lighting systems.
4. Defects in the electrical system, such as
shorted or pinched wires.
5. Extended driving at a slow speed while
using many accessories.
6. Loose or poor
connections, previous improper charging of
a run-down battery, or loose hold-down
clamp bolts.
7. High-resistance connections or defects in
the cranking system.
9.15 "BATTERY VOLTAGE
PICTOGRAM
If the "BATTERY VOLTAGE WARNING"
(Low Voltage – Connect Battery Charger)
pictogram shows up
Information Display), check the voltmeter gauge
to determine if the battery voltage is too high or
too low.
9.15.1

Voltage Gauge Definitions

Voltmeter drops below 24.4 volts dc
Check alternator output.
o
Check battery connections.
o
Check battery equalizer connections.
o
Voltmeter exceeds 30 volts dc
Check alternator output (voltage regulator
o
might be defective).
Check battery connections.
o
Checking Battery Balance
and disconnect
battery cable-to-post
WARNING"
in the DID (Driver