C.E. Niehoff & Co. N1240-3, N1243-2 Troubleshooting Guides

N1240/N1243 Series Troubleshooting Guide

for N1240-3/N1243-2 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

NOTICE

Indicates presence of hazards that will or can cause minor personal injury or property damage if ignored.

Indicates special instructions on installation, operation or maintenance that are important but not related to personal injury hazards.

Table of Contents

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

Section 2: CAN/J1939 Diagnostics .............................. 3

Section 3: Basic Troubleshooting ................................ 4

Section 4: Advanced Troubleshooting ......................... 5

Battery Conditions

NOTICE

• 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.

Until temperatures of electrical system components stabilize, these conditions may be observed during cold start voltage tests.

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 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 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 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 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 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 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 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 N1240-3/N1243-2 Alternators Description and Operation

N1240-3 and N1243-2 28 V 260 A alternators are internally rectified. All windings and current-conducting components are non-moving, so there are no brushes or slip rings to wear out.

After engine is running, N3218 regulator receives energize signal. Regulator monitors alternator rotation and provides field current only when it detects alternator shaft rotating at or above idle speed.

After regulator detects alternator rotation, it gradually applies field current, preventing an abrupt mechanical load on accessory drive system. The soft start may take up to 20 seconds.

N3218 regulator used with these units also

• is negative temperature compensated. Setpoint is

28.8 ± 0.5 V at 72 F when configured to operate with 6TMF type batteries.

• provides overvoltage cutout (OVCO). Regulator will trip OVCO when system voltage rises above setpoint by 3 V for longer than 3 seconds. OVCO feature detects high voltage and reacts by opening alternator field circuit and turning off alternator. Restarting engine or waiting until system voltage drops 5 V below setpoint will reset OVCO circuit.

• maintains alternator steady-state output voltage at regulated settings as vehicle electrical loads are switched on and off.

(next to regulator connector)

Figure 1 — N1240-3/N1243-2 Alternators and

B+ terminal

B– terminal

N3218 Regulator Terminals

IGN terminal

Page 2

Figure 2 — N1240-3/N1243-2 Alternators with N3218 Regulator

TG0040A

Section 2: CAN/J1939 Diagnostics

—

CAN/J1939 Interface

DESCRIPTION AND OPERATION

The CEN N3218 digital regulator is compatible with SAE J1939 communications standard for vehicle networking.

CEN uses MIL-STD connector MS3112E12-10P to interface between the N3218 and the vehicle J1939 databus and battery box sensors. Mating connector is MS3116E12-10S or equivalent. If this connection is not used, it must be sealed with connector cover MS3181-12CA or equivalent. Connector pinout is shown in Table 1. Message content is shown in Table 2.

Battery box sensing inputs connect to battery pack positive terminal (pin J) and battery box thermistor (pin H). Thermistor is 10K NTC with 32650Ω at 0ºC,

10000Ω at 25ºC, 3601Ω at 50ºC and 1% interchangeability. Thermistor location should be chosen so that it closely represents battery case temperature. Thermistor connects between pin H and vehicle chassis, battery pack negative terminal, or negative bus bar. If either sensing input (pin H or J) is not used, regulator will default to internal temperature and alternator voltage.

TABLE 1 – J1939 Connector

Circuit Identification

Identification

J1939+

J1939–

J1939/SHLD

B–/GND

Mfr use only

Ext. Temp. Sense

Ext. Voltage Sense

unused

Figure 3 – J1939

Connector Pins

TABLE 2 – N3218 Regulator/J1939 Readout Diagnostics (see Table 3)

Regulator Readout

Alternator Speed

Alternator Voltage

Battery Voltage

Regulator Temp.

Alternator Current

Alternator Load

Battery Temp.

Stator Voltages

PGN Name 1 (1) 2 3 4 5 6 7 8 FED5 Alt. Speed Alt. Speed FEF7 Alt. Voltage Alt. Voltage Batt. Voltage FEA7 Alt. Temp. Reg. Temp.

FFC8 Proprietary #1 Alt. Current FFC9 Proprietary #2

FFCA Proprietary #3 Stator 1 Voltage Stator 2 Voltage

Notes: (1) Byte 1 broadcast closest to CAN frame ID.

(2) Contact C. E. Niehoff & Co. for definition of custom proprietary message content.

Expected Reading

1500 to 8000 RPM

26 to 30 V (when charging)

–40 to 125ºC

0 to 300 A

0 to 100%

–40 to 80ºC

10 to 18 V (when charging)

(2) (2)

OVCO Count

Table 3

(2) (2)

Action If Expected Reading Not Present

Check belts and pulley.

Check alternator drive and regulator IGN signal.

Check battery box voltage sense signal.

Check regulator.

Check alternator output cabling.

Check battery box thermistor.

Check alternator belts and output.

Message Data

Alt. Hrs. Load Batt. Temp.

(2) (2) (2) (2) (2)

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