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TG0060A

Table of Contents

Section A: Wiring ...............................................................2
Section B: Basic Troubleshooting ......................................3
Section C: Advanced Troubleshooting ......................... 4 – 5

Battery Conditions

 

Until temperatures of electrical  

 

system components stabilize, these  

 

conditions may be observed during  

 

cold start voltage tests.

•  Maintenance or low maintenance battery:

—  Immediately after engine starts, system volts are  
 

lower than regulator setpoint with medium amps.

—  3-5 Minutes into charge cycle, system volts are  
 

higher and amps are dropping.

—  5-10 Minutes into charge cycle, system volts are  
 

at, or nearly at, regulator setpoint and amps are  

 

reduced to a minimum.

—  Low maintenance battery has same characteris- 
 

tics with slightly longer recharge times.

• Maintenance-free 

battery:

—  Immediately after engine start, system volts are 
 

lower than regulator setpoint with low charging  

 amps.
—  15-30 minutes into charge cycle, volts and amps  
 

are still low.

—  15-30 minutes into charge cycle, volts increase  
 

several tenths. Amps increase gradually, then  

 

quickly, to medium to high amps.

—  20-35 minutes into charge cycle, volts increase  
 

to setpoint and amps decrease.

•  High-cycle maintenance-free battery:

—  These batteries respond better than standard  
 

maintenance-free. Charge acceptance of these  

 

batteries may display characteristics similar to  

 maintenance 

batteries.

NOTICE

Hazard De

fi

 nitions

These terms are used to bring attention to presence of hazards 
of various risk levels or to important information concerning 
product life.

NOTICE

C524 Alternator 

Troubleshooting Guide

Charge Volt and Amp Values

The volt and amp levels are a function of the battery state of 
charge. If batteries are in a state of discharge, as after ex-
tended cranking time to start the engine, the system volts, 
when measured after the engine is started will be lower 
than the regulator setpoint and the system amps will be 

high. This is a normal condition for the charging system. 
The measured values of system volts and amps will depend 
on the level of battery discharge. In other words, the greater 
the battery discharge level, the lower the system volts and 
higher the system amps will be. The volt and amp readings 
will change, system volts reading will increase up to regula-
tor setpoint and the system amps will decrease to low level 
(depending on other loads) as the batteries recover and 
become fully charged.
• 

Low Amps:

 A minimum or lowest charging system amp 

value required to maintain battery state of charge, 
obtained when testing the charging system with a fully 
charged battery and no other loads applied. This value 
will vary with battery type. 

• 

Medium Amps:

 A system amps value which can cause 

the battery temperature to rise above the adequate 
charging temperature within 4-8 hours of charge time. 
To prevent battery damage, the charge amps should be 
reduced when battery temperature rises. Check battery 
manufacturer’s recommendations for proper rates of 
charge amps.

• 

High Amps:

 A system amps value which can cause the 

battery temperature to rise above adequate charging 
temperature within 2-3 hours. To prevent battery dam-
age, the charge amps should be reduced when the 
battery temperature rises. Check battery manufactur-
er’s recommendations for proper rates 
of charge amps.

• 

Battery Voltage:

 Steady-state voltage value as 

measured with battery in open circuit with no battery 
load. This value relates to battery state of charge. 

• 

Charge Voltage:

 A voltage value obtained when the 

charging system is operating. This value will be higher 
than battery voltage and must never exceed the regula-
tor voltage setpoint.

• 

B+ Voltage:

 A voltage value obtained when measuring 

voltage at battery positive terminal or alternator B+ 
terminal.  

• 

Surface Charge:

 A  higher than normal battery voltage 

occurring when the battery is removed from a battery 
charger. The surface charge must be removed to deter-
mine true battery voltage and state of charge.

• 

Significant Magnetism:

 A change in the strength or 

intensity of a magnetic field present in the alternator 
rotor shaft when the field coil is energized. The mag-
netic field strength when the field coil is energized 
should feel stronger than when the field is not ener-
gized.

• 

Voltage Droop or Sag: 

A normal condition which 

occurs when the load demand on the alternator is 
greater than rated alternator output at given rotor 
shaft RPM.   

 

Indicates presence of hazards that  

 

will or can cause minor personal  

 

injury or property damage if  

 ignored.

 

Indicates special instructions on  

 

installation, operation or mainte- 

 

nance that are important but not  

 

related to personal injury hazards.

CAUTION

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