Charging System Service Chapter 35 Page 459

Test the Battery First Make sure the Battery can be used to confirm this is fully charged or has the ability to be charged. A DVOM and/or charger The Battery should be 12.6 volts The battery can have 13.0 volts – this is called a surface charge, it can be removed by turning on the headlights for 30 seconds

Quick Voltage Check

Initial Checks Check for corrosion and intact wiring. Wiggle wires while the engine runs. Keep an eye on the amps reading. (inside gauge or amp meter) Listen to noises from the alternator and belt area. Check over the belt (the engine off, of course) for damage Try to make belt slip by turning it manually. About an inch of deflection over the longest span is good.

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

Alternator Rating Cars up to the eighties needed about a 50 amp alternator. Cars in since the eighties have much more in the way of onboard electronics so a 100 amp alternator. Trucks have traditionally needed a more powerful alt. it is not uncommon to see 125-200 amp alts. If you add a bunch of electronics; amps CD, DVD, TV, etc. you will have to upgrade the alternator and the battery.

Alternator Testing There is four tests: Charging system output- loads (creates a draw) the system and checks amps output. Regulator voltage setting- Checks for minimum and maximum settings. Alternator full field test- tests the max that the alternator can put out. Charging circuit resistance tests- measures voltage drop and loss of power to and from the alternator.

Our Charger This unit has a tester unit on top and a charging unit below. This unit is able to test all four alternator tests.

Testing Precautions Connecting the test wires wrong can damage the system. Don’t full field the alt. for more than 10 seconds. Don’t connect or disconnect components while engine is running. Don’t disconnect the regulator while the engine is running. Don’t operate the alt. without the wiring connected. Using the Vat 45 is much safer for you and the system than manual ways of testing.

Manually Full Fielding

Alternator Service Like the starter and other components on the vehicle the repair is limited to replacement with a few exceptions. Changing the pulley and fan. Sometimes you purchase a new alternator you have to use the old fan and pulley. Rotor checks, Stator checks, diode test, brush, and bearing work requires disassembly of the alternator.

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

Testing Rotor Between the slip rings and the iron core there should be 1. on the ohmmeter (isolated). Between the slip rings there should be near .000 ohms or continuity (connected)

Testing Diodes A good diode will show high resistance in one direction and infinity in the other (1. and .000) Remember it is a one way check valve. Bad diodes will read open (.1) or low resistance (.000) in both directions. To check them; just place the leads to the DVOM and take a reading, then reverse the leads and take another reading. *Check each diode(3) Voltage regulator Positive Lead Negative Lead

Noisy Diodes Sometimes the radio picks up noise that sounds like a siren that changes with rpm’s. This indicates a bad diode, (sometimes the sparkplug wires are to thin). A bad diode may cause a growling or a whining sound.

Adjusting the Belt

Your Job. Complete chapter Questions 1-10 (review) and 1-10 (ASE-style). Page 465 Write on a separate paper and write out the complete question and your answer. ( do not write the other answer options). Complete the chapter worksheet (I will give it out). You may write on it. File all items in your note book. Notebooks will be graded in the future.