C.E. Niehoff & Co. C651, C654 Troubleshooting Guides

600 Series Troubleshooting Guide

for C651 and C654 Alternators

Hazard Definitions

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

CAUTION

personal injury or property damage if ignored.

NOTICE

maintenance that are important but not related to personal injury hazards.

Indicates presence of hazards that will or can cause minor

Indicates special instructions on installation, operation or

Table of Contents

Section 1: Wiring Diagram ....................................... 2

Section 2: Basic Troubleshooting ............................ 3

Section 3: Advanced Troubleshooting ................. 4 – 7

Battery Conditions

NOTICE

conditions may be observed during cold start voltage tests.

• Maintenance/low maintenance battery: — Immediately after engine starts, system volts

are lower than regulator setpoint with medium amps.

— 3-5 minutes into charge cycle, higher system

volts and reduced amps.

— 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 charac-

teristics with slightly longer recharge times.

• Maintenance-free battery: — Immediately after engine start, system volts are

lower than regulator setpoint with low amps.

— 15-30 minutes into charge cycle, still low volts

and low amps.

— 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.

Until temperatures of electrical system components stabilize, these

Charge Volt and Amp Values

The volt and amp levels are a function of the batterystate of charge. If batteries are in a state of discharge, as after extended cranking time to start the engine, the system volts, when measured after the engine is started will be lower than the regulator set point 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 and system volts reading will increase up to regulator set point 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 charge amps rates.

• 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 damage the charge amps should be reduced when the battery temperature rises. Check battery manufacturer’s recommendations for proper charge amp rates.

• 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 regulator voltage set point.

• B+ Voltage: A voltage value obtained when mea-

suring 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 determine 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 magnetic field strength when the field coil is energized should feel stronger than when the field is not energized.

• 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.

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Page 1

Section 1: Wiring Diagram

CEN C651 and C654 Alternators Description and Operation

C651 28 V (240 A)/14 V (100 A) and C654 28 V (260 A) /14 V (100 A) alternators are internally rectified. All windings and current-transmitting components are non-moving, so there are no brushes or slip rings to wear out. Energize switch activates regulator. Regulator cycles field coil off and on until system voltage is is reached. Upper voltage (28 V) is rectified with standard diodes. Lower voltage (14 V) circuit output current is controlled by SCRs in the drive end housing. Alternator output current is self-limiting and will not exceed rated capacity of alternator.

A2-306 regulator used with these units:

• is for use with batteries connected in series, not parallel.

CAUTION

series not parallel circuits. See Figures 2 and 3 for connections.

• maintains alternator output voltage at regulated setting as vehicle electrical loads are switched on and off.

Regulator is designed to control system through

R Terminal

E Terminal

Tricolor (R, A, G) diagnostic LED

28 V B+ Terminal

14 V B+ Terminal

B– Terminal

• monitors low and high batteries in system separately.

• limits 14 V alternator output current to 100 A. 14 V source from R terminal on regulator is limited to 1 A when alternator is rotating.

STATOR

RECTIFIER

SCR GATE

STATOR

FIELD

Figure 1 — C651 and C654 Alternator Terminals

28 V

B+

14 V

ENERGIZE SWITCH

H (unused)

REGULATOR

14 V LOAD

28 V LOAD

BATTERY

Page 2

B–

REGULATOR RECEPTACLE

ALTERNATOR

Figure 2 — C651 and C654 Alternator with Regulator

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Section 2: Basic Troubleshooting

A . Tools and Equipment for Job

• Digital Multimeter (DMM)

• Ammeter (digital, inductive)

• Jumper wire

B. Identification Record

List the following for proper troubleshooting:

Alternator model number _______________________

❏

Regulator model number _______________________

❏

Setpoints listed on regulator ____________________

❏

C. Preliminary Check-out

Check symptoms in Table 1 and correct if necessary.

TABLE 1 – System Conditions

SYMPTOM

Low Voltage Output

High Voltage Output

No Voltage Output

No 14 V Output

Check:loose drive belt; low

battery state of charge.

Check:current load on system

is greater than alternator can produce.

Check:defective wiring or poor

ground path; low regulator setpoint.

Check:defective alternator and/

or regulator. Check:wrong regulator. Check:high regulator setpoint. Check:defective regulator. Check:alternator. Check:broken drive belt. Check:battery voltage at

alternator output terminal. Check:defective alternator and/

or regulator. Check:defective regulator.

Go to Chart 3, page 6.

ACTION

D. Basic Troubleshooting

1. Inspect charging system components for damage

Check connections at B– cable, B+ cables, and regulator harness. Repair or replace any damaged component before troubleshooting.

2. Inspect vehicle battery connections Connections must be clean and tight.

3. Determine battery voltages and states of

charge

If batteries are discharged, recharge or replace batteries as necessary. Electrical system cannot be properly tested unless batteries are charged 95% or higher. In addition, open circuit voltages must be within ± 0.2 V.

4. Connect meters to alternator Connect meters as shown in Figure 3, page 4.

5. Operate vehicle Observe charge voltage.

CAUTION

battery, immediately shut down system. Electrical system damage may occur if charging system is allowed to operate at high voltage. Go to Table 1 at left.

Regulator setpoints indicate two different voltage measurements for this system. First setpoint is sum of low battery and high battery voltage measurements. Second setpoint is voltage measured across low battery only.

If voltage is at or below regulator setpoint, let charging system operate for several minutes to normalize operating temperature.

6. Observe charge volts and amps in each circuit Charge voltage should increase and charge amps should decrease. If charge voltage does not increase within ten minutes, continue to next step.

7. Batteries are considered fully charged if charge voltage is at regulator setpoint and charge amps remain at lowest value for 10 minutes.

8. If charging system is not performing properly, go to Chart 4, page 7.

If charge voltage is above 16 V on either high or low

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