Charging System Charging System ServiceService

Chapter 35Chapter 35

Page 459Page 459

Test the Battery FirstTest the Battery First

Make sure the Battery can be used to Make sure the Battery can be used to confirm thisconfirm this

is fully charged or has the ability to be is fully charged or has the ability to be charged. charged. A DVOM and/or charger The Battery A DVOM and/or charger The Battery

should be 12.6 voltsshould be 12.6 volts The battery can have 13.0 volts – this is The battery can have 13.0 volts – this is

called a surface charge, it can be called a surface charge, it can be removed by turning on the headlights for removed by turning on the headlights for 30 seconds30 seconds

Quick Voltage CheckQuick Voltage Check

Initial ChecksInitial Checks Check for corrosion and intact wiring.Check for corrosion and intact wiring. Wiggle wires while the engine runs. Keep an eye Wiggle wires while the engine runs. Keep an eye

on the amps reading. (inside gauge or amp meter)on the amps reading. (inside gauge or amp meter) Listen to noises from the alternator and belt area.Listen to noises from the alternator and belt area. Check over the belt (the engine off, of course) for Check over the belt (the engine off, of course) for

damage damage Try to make belt slip by Try to make belt slip by turning it manually. turning it manually. About an inch of deflection About an inch of deflection over the longest span is good.over the longest span is good.

Bearing LocationsBearing Locations

Noisy bearings is the most common complaint other than the alternator completely failing.

Alternator RatingAlternator Rating

Cars up to the eighties needed about a 50 Cars up to the eighties needed about a 50 amp alternator.amp alternator.

Cars in since the eighties have much more in Cars in since the eighties have much more in the way of onboard electronics so a 100 amp the way of onboard electronics so a 100 amp alternator. alternator.

Trucks have traditionally needed a more Trucks have traditionally needed a more powerful alt. it is not uncommon to see 125-powerful alt. it is not uncommon to see 125-200 amp alts. 200 amp alts.

If you add a bunch of electronics; amps CD, If you add a bunch of electronics; amps CD, DVD, TV, etc. you will have to upgrade the DVD, TV, etc. you will have to upgrade the alternator and the battery.alternator and the battery.

Alternator TestingAlternator Testing

There is four tests: There is four tests: Charging system output- loads (creates a Charging system output- loads (creates a

draw) the system and checks amps output.draw) the system and checks amps output. Regulator voltage setting- Checks for Regulator voltage setting- Checks for

minimum and maximum settings.minimum and maximum settings. Alternator full field test- tests the max Alternator full field test- tests the max

that the alternator can put out.that the alternator can put out. Charging circuit resistance tests- Charging circuit resistance tests-

measures voltage drop and loss of power measures voltage drop and loss of power to and from the alternator.to and from the alternator.

Our ChargerOur Charger

This unit has a tester unit on topThis unit has a tester unit on top

and a charging unit below.and a charging unit below. This unit is able to test all four This unit is able to test all four

alternator tests.alternator tests.

Testing PrecautionsTesting Precautions Connecting the test wires wrong can damage Connecting the test wires wrong can damage

the system.the system. Don’t full field the alt. for more than 10 Don’t full field the alt. for more than 10

seconds.seconds. Don’t connect or disconnect components while Don’t connect or disconnect components while

engine is running.engine is running. Don’t disconnect the regulator while the Don’t disconnect the regulator while the

engine is running.engine is running. Don’t operate the alt. without the wiring Don’t operate the alt. without the wiring

connected.connected. Using the Vat 45 is much safer for you and the Using the Vat 45 is much safer for you and the

system than manual ways of testing.system than manual ways of testing.

Manually Full FieldingManually Full Fielding

Alternator ServiceAlternator Service

Like the starter and other Like the starter and other components on the vehicle the repair components on the vehicle the repair is limited to replacement with a few is limited to replacement with a few exceptions. exceptions. Changing the pulley and fan. Sometimes Changing the pulley and fan. Sometimes

you purchase a new alternator you have you purchase a new alternator you have to use the old fan and pulley.to use the old fan and pulley.

Rotor checks, Stator checks, diode test, Rotor checks, Stator checks, diode test, brush, and bearing work requires brush, and bearing work requires disassembly of the alternator. disassembly of the alternator.

Testing StatorTesting Stator

The different legs and from legs to The different legs and from legs to iron core should be open 1. on the iron core should be open 1. on the ohmmeter. (isolated form one ohmmeter. (isolated form one another).another).

Testing RotorTesting Rotor

Between the slip rings and the iron Between the slip rings and the iron core there should be 1. on the core there should be 1. on the ohmmeter (isolated).ohmmeter (isolated).

Between the slip rings there should Between the slip rings there should be near .000 ohms or continuity be near .000 ohms or continuity (connected)(connected)

Testing DiodesTesting Diodes A good diode will show high resistance in A good diode will show high resistance in

one direction and infinity in the other (1. one direction and infinity in the other (1. and .000)and .000) Remember it is a one way check valve.Remember it is a one way check valve.

Bad diodes will read open (.1) or low Bad diodes will read open (.1) or low resistance (.000) in both directions.resistance (.000) in both directions.

To check them; just place To check them; just place the leads to the DVOM andthe leads to the DVOM andtake a reading, then reverse take a reading, then reverse the leads and take another the leads and take another reading.reading.*Check each diode(3)*Check each diode(3)

Voltage regulator

Positive Lead

Negative Lead

Noisy DiodesNoisy Diodes

Sometimes the radio picks up noise Sometimes the radio picks up noise that sounds like a siren that changes that sounds like a siren that changes with rpm’s.with rpm’s.

This indicates a bad diode, This indicates a bad diode, (sometimes the sparkplug wires are (sometimes the sparkplug wires are to thin).to thin).

A bad diode may cause a growling or A bad diode may cause a growling or a whining sound.a whining sound.

Adjusting the BeltAdjusting the Belt

Your Job.Your Job.

Complete chapter Questions 1-10 Complete chapter Questions 1-10 (review) and 1-10 (ASE-style). Page 465(review) and 1-10 (ASE-style). Page 465

Write on a separate paper and write Write on a separate paper and write out the complete question and your out the complete question and your answer. ( do not write the other answer answer. ( do not write the other answer options). options).

Complete the chapter worksheet (I will Complete the chapter worksheet (I will give it out). You may write on it. give it out). You may write on it.

File all items in your note book.File all items in your note book. Notebooks will be graded in the future.Notebooks will be graded in the future.