C.E. Niehoff & Co. N1313 Troubleshooting Guides
C.E. Niehoff & Co.
N1313 Alternator
Troubleshooting Guide
Hazard Definitions
These terms are used to bring attention to presence of hazards
of various risk levels or to important information concerning
product life.
Indicates presence of hazard(s)
CAUTION
that will or can cause minor
personal injury or property
damage if ignored.
Indicates special instructions on
NOTICE
installation, operation or mainte nance that are important but not
related to personal injury hazards.
Table of Contents
Section A: Wiring Diagram ......................................2
Section B: Basic Troubleshooting ............................3
Section C: Advanced Troubleshooting ................ 4 – 8
Battery Conditions
Until temperatures of electrical
NOTICE
system components stabilize, these
conditions may be observed during
cold-start voltage tests.
• Maintenance/Low Maintenance Battery
— Immediately after engine starts, system volts are
lower than regulator setpoint, amps are medium.
— 3–5 minutes into charge cycle, system volts
increase, amps decrease.
— 5–10 minutes into charge cycle, system volts
increase to, or near, regulator setpoint and amps
decrease to a minimum.
— Low maintenance battery has same characteristics
with slightly longer recharge times.
• Maintenance-free Battery
— Immediately after engine starts, system volts are
lower than regulator setpoint, low charging amps.
— Once charge cycle begins, low volts and low amps
are still present.
— After alternator energizes, voltage will increase
several tenths. Amps will increase gradually, then
quickly, to medium to high amps.
— F i n a l l y , v o l t s w i l l i n c r e a s e t o s e t p o i n t a n d a m p s w i l l
decrease.
The time it takes to reach optimum voltage and amperage will vary with engine speed, load, and ambient
temperature.
• 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.
• AGM (Absorbed Glass Mat) Maintenance-free Battery
These dry-cell batteries respond better than standard
maintenance-free. If battery state of charge drops to
75% or less, batteries should be recharged to 95% or
higher separately from the engine’s charging system to
avoid damaging charging system components and to
provide best overall performance. Charge acceptance of
these batteries may display
maintenance batteries.
characteristics similar to
Battery Charge Volt and Amp Values
Volt and amp levels fluctuate depending on the battery state
of charge. If batteries are in a state of discharge—as after
extended cranking time to start the engine—system volts
will measure lower than the regulator setpoint after the
engine is restarted and system amps will measure higher.
This is a normal condition for the charging system; the
greater the battery discharge level, the lower the system
volts and the higher the system amps. The volt and amp
readings will change as batteries recover and become fully
charged: system volts will increase to regulator setpoint
and system amps will decrease to low level (depending on
other loads).
• Low Amps: 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: System amps value which can cause
the battery temperature to rise above 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
amp rates.
• High Amps: System amps value which can cause
the battery temperature to rise above adequate charging
temperature within 2-3 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
amp rates.
• Battery Voltage: Steady-state voltage value as mea-
sured with battery in open circuit with no battery load.
This value relates to battery state of charge.
• Charge Voltage: Voltage value obtained when the
charging system is operating. This value will be higher
than battery voltage and must never exceed the regulator voltage setpoint.
• B+ Voltage: Voltage value obtained when measuring
voltage at battery positive terminal or alternator B+
terminal.
• Surface Charge: Higher than normal battery voltage
occurring when the battery is disconnected from
battery charger. The surface charge must be removed
to determine true battery voltage and state of charge.
• Significant Magnetism: Change in strength or inten-
sity of a magnetic field present in 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: Normal condition occurring
when the load demand on alternator is greater than
rated alternator output at given rotor shaft RPM.
TG16F
Page 1
Section A: Description and Operation
CEN N1313 Dual Voltage Alternator
Description and Operation
N1313 300 A (28 /14 V) dual voltage alternator is internally rectified. All windings and current-conducting
components are non-moving, so there are no brushes or
slip rings to wear out. Energize switch (commonly an oil
pressure switch or ignition switch) activates regulator.
Field coil is then energized when rotation is detected.
Upper voltage (28 V) is rectified with standard diodes.
Lower voltage (14 V) circuit output current is controlled
by SCRs. Alternator output current is self-limiting and
will not exceed rated capacity of alternator.
N3039 and N3222 regulators used with these units also
• are flat temperature compensated. Setpoints are
28.0 ± 0.2 V and 14.0 ± 0.2 V.
• provide overvoltage cutout (OVCO). Regulator will
trip above 32 V for 28 V system (16 V for 14 V
system) longer than 2 seconds. OVCO feature detects
high voltage and reacts by signaling relay in F–
alternator circuit to open, turning off alternator.
Restarting engine resets OVCO circuit. If vehicle is
run in OVCO mode, OVCO will automatically reset
when system voltage drops to 22 V. Regulator
regains control of alternator below output voltage.
• maintain alternator output voltage at regulated
settings as vehicle electrical loads are switched
on and off.
28 V B+
terminal
14 V B+
terminal
B– terminal
(N3222 only)
AC terminal
Figure 1 — N1313 Alternator and
N3039 or N3222 Regulator Terminals
E terminal
Page 2
Figure 2 — N1313 Alternator with Regulator
TG16F
Section B: Basic Troubleshooting
Tools and Equipment for Job
• Digital Multimeter (DMM)
• Ammeter (digital, inductive)
• Jumper wires
Identification Record
List the following for proper troubleshooting:
Alternator model number _________________________
Regulator model number ________________________
Setpoint listed on regulator _______________________
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 alternator or
regulator.
Check: wrong regulator.
Check: defective regulator.
Check: alternator.
Check: presence of energize signal.
Check: battery voltage at alternator
output terminal.
Check: defective alternator or
regulator.
Go to Chart 2, page 6.
ACTION
Basic Troubleshooting
1. Inspect charging system components
Check connections at ground cables, positive
cables, and regulator harness. Repair or replace
any damaged component before troubleshooting.
2. Inspect connections of vehicle batteries
Connections must be clean and tight.
3. Determine battery type, voltage and state
of charge
Batteries must be all the same type for system
operation. If batteries are discharged, recharge or
replace batteries as necessary. Electrical system
cannot be properly tested unless batteries are
charged 95% or higher. See page 1 for details.
Nominal battery voltage for 28 V systems is 25.2
±0.2 V; for 14 V systems is 12.6 ±0.2 V. Less than
25 V or 12.4 V indicates no charge condition when
engine is running.
4. Connect meters to alternator
Connect red lead of DMM to alternator 28 V B+
terminal and black lead to alternator B – terminal.
Clamp inductive ammeter on 28 V B+ cable.
5. Operate vehicle
Observe charge voltage at batteries with engine
running (nom. 27-28 V or 13.5-14.0 V).
If charge voltage is above 32 V
for 28 V system or 16 V for 14 V
system, immediately shut down
system. Electrical system
damage may occur if charging
system is allowed to operate at
excessive voltage. Go to Table 1
at left.
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
in- crease 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 1, page 5.
CAUTION
TG16F
Page 3
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