C.E. Niehoff & Co. N1246-1 Troubleshooting Guides User Manual
C.E. Niehoff & Co. Hardware

Page 1
TG0049A
Table of Contents
Section 1: Wiring Diagram .......................................2 
Section 2: Basic Troubleshooting .............................3
Section 3: Advanced Troubleshooting ................ 4 – 6
Battery Conditions
Until temperatures of electrical
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 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
charging
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.
NOTICE
Hazard Defi nitions
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 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
NOTICE
Troubleshooting Guide
for N1246-1 Alternator
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 extended cranking time to start the engine, the sys-
tem 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 regulator 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 recommenda-
tions 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 damage the charge amps should be reduced 
when the battery temperature rises. Check battery 
manufacturer’s recommendations for proper rates 
of charge amps.
•
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: 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 setpoint.
•
B+ Voltage: A voltage value obtained when measur-
ing voltage at battery positive terminal or alternator 
B+ terminal. 
•
Surface Charge: A higher than normal battery volt-
age 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 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. 
