Charging testing service Flashcards
alternator drive belt in poor condition and not tensioned properly can
result in an undercharged battery
all belts are considered used when
they have been operating for more then 15 min
drive belt glazing is caused by
heat friction when a loose belt slips or oil/grease on the belt and pulley
separating layers
oil grease or belt design can cause the belt to fall apart in layers
Jagged or streaked side walls
can be the result of a foreign object embedded in the pulley drive surface
tensile breaks
are breaks in the belts cord body can be caused by prying or forcing belt over pulleys during installation
multi ribbed belts must be check for
uneven ribs in the belt
cracks in the belt
signs of an old belt
if the belt has evenly spaced deep bottom cracks means the idler diameter is to small and the belt is being over flexed
duel belts or matched belts
must be replaced together at the same time
when inspecting pulleys
hold a small straight edge against the side walls and check for worn groves and oil and grease build up if it cannot be cleaned it must be replaced
when checking belt tension
use a belt tension gauge
when working on drive belts you should always make sure
the batteries are disconnected to ensure the unit will not start
is a multi ribbed belt is slipping
check the belt tensioner is operating in the right range
if it is it may have to be replaced
alternator alignment
use a straight edge
pulleys must not be offset more than 1mm for every 20 cm of distance between the pulley centers
when should you check belt alignment
every time belt maintenance is preformed or alternators are being replaced
when mounting an alternator
use a minimum of grade 5 bolts with hardened washers no less than 3mm thick and flanged locknuts
when checking insulated and ground circuits
check for unwanted high resistances resulting in excessive voltage drops
if the alternator senses a false voltage created by unwanted high resistances
the units batteries will be under charged
when checking alternator and batteries circuits make sure to
not exceed the rated output of the alternator
if you do damage to the systems electrical components could be caused
why must you move quickly when using a carbon pile and a volt meter testing for voltage drops in a circuit
because the carbon pile will over heat quickly
if the the sum of the voltage drops is greater than _ in a 12 volt system it will not charge batteries correctly
.5 volt
if the sum of the voltage drops in a 24 volt system is greater than _ it will not charge the batteries correctly
1 volt
when preforming on unit electrical checks the components must be
at normal shop temperatures 16 to 23 degrees
symptoms of not completely charged batteries
slow or no engine cranking
low voltmeter reading
dim work lights
slow cycling of equipment warning lights
symptoms of over charged batteries
voltmeter readings are high
lights burn very bright or burn out rapidly
batteries emits bad smelling fumes
batteries spews out acid or swells or distorts
batteries can become sulfated if
they are undercharged due to unbalanced internal resistance
if batteries have become sulfated
will have less capacity to convert chemical energy into electrical energy
if batteries have an unbalanced internal resistance
they will be unable to crank engine during start up
before preforming any charging system diagnostics
check the battery group for proper charging and condition
when testing batteries for proper operation
must be properly charger as to not interfere with voltage and current readings
OCV of a battery group system is 12.8 or 25.6
batteries have a surface charge on there plates and it must be removed
leaving the lights on for 3 min will remove surface charge
OCV of a battery group system is under 12.6 or 25.2
the batteries are undercharged and must be charged and re tested
important to disconnect batteries from system to avoid component damage
when testing alternator regulator voltage under a no load condition
all electrical loads must be turned off
set engine speed to provide maximum alternator output
after 2 min record voltage reading
alternator regulator test results
- 8-14.8 volts for a 12 volt system
- 6-29.6 volts for a 24 volt system
regulator is set correctly
Alternator regulator test results
less than 13.8-27.6 volts or
more than 14.8-29.6 volts
regulator needs to be adjusted
the regulator must not be
30% more than the rated output
if the alternator is not within _ of the rated out put it must be replaced or repaired
10%
most common internal alternator faults
open field (brushes worn ) shorted stator open stator shorted diode open diode
effects of an open stator winding
amperage output will be greatly reduced
effects of a shorted diode
allows current to flow in both directions causing a large drop in alternator current output
output may be reduced as much as 60 to 70 %
could easily over heat
effects of an open diode
an open rectifier diode will produce a whining sound
current will be reduced by 33 %
when disassembling alternators
you may need to use special disassembly tools
when disassembling alternator housings never
use a hammer and a chisel to index the housing for orientation this will cause electrical insulation breakdown and distortion of the case
when removing the shaft nut on the alternator
hold the alternator with a strap wrench
do not hold the fan blades they can be easily damaged or warped becoming unbalanced and useless
if bolts in the housing are seized
you can carefully warm a localized spot on the case
jarring the bolts and applying penetrating oil will also help
if the drive end housing binds to the stator when removing
tap the aluminium case gently with a plastic or rawhide mallet
when checking the diode trio
use the DDM in diode check mode and check for a millivolt reading in forward bias
meter should read OL in reverse bias
if any of the three diodes in the diode trio exhibit a short or open condition
the whole diode trio must be replaced
if a diode in the rectifier bridge exhibits a shorted or open condition
you can replace the individual diode
when visually inspecting the stator windings
look for signs of overheating or bare wires
when conducting a stator ground fault test and your multi meter reads (infinite ohms)
this indicates that the stator is not grounded
when checking for opens in the rotor windings connect each lead of your meter to the slip rings if your meter reads (OL)
there is an open in the windings and the rotor must be replaced
when checking for ground faults on the rotor your meter is connected to the slip ring and the metal components and your meter reads less than (OL)
the rotor has a ground fault and must be replaced
how do you check for shorts or excessive resistance in rotor windings
by connecting a battery and a ammeter in series with the surface of the two slip rings
should also connect the volte meter in parallel to check for proper volt reading
if the rotor slip rings at dirty you can clean them with
400 or more grit sandpaper
why should you not use emery cloth to clean slip rings
because the metal particles can adhere to the rotor and cause premature brush wear
slip rings that are rough or out of round can be refinished
always make sure to be within _ of the total allowable runout
0.05 mm
if the rotor must be removed from the drive end housing
it must be pressed out
can be easily cracked because they are not designed to absorb axial load
when inspecting the brushes you should replace them when
they are worn over half or show signs of burning or cracked
if brushes are to be reused you must
rematch the wear pattern on the brush to the slip ring it was on
capacitors are tested for
capacity
leakage
series resistance
when testing a capacitor for leakage or series resistance you must use
a capacitor tester
why should you never soak the stator windings in petroleum based solvents
because this can dissolve the components insulation layer causing ground faults or electrical shorts
when using electrical contact cleaner it must not contain
silicone because it will attack the brush material causing short brush life
after reassembling an alternator you should
bench test it for proper operation
two types of sound to listen for when troubleshooting
electrical and mechanical
electrically generated sounds
will produce a whining noise that varies in intensity as the electrical load changes
mechanical sounds
do not change when extra load is placed on alternator
when changing voltage regulator settings
should be changed in steps of 1/10 of a volt and allow time for system to re-evaluate before changing again
