Alternator & Starter Q&A
Alternator Q&A
What is an alternators amperage output at idle?
Alternators operate on a supply and demand situation and do not have a set amperage output at idle.
What should the system voltage output be?
On a 12 volt system the high cutout voltage should be between 14.3 - 14.9 depending on the voltage regulator installed on your alternator. This voltage will slowly drop off until the battery is fully charged and the electrical load is low.
On a 12 volt system the high cutout voltage should be between 14.3 - 14.9 depending on the voltage regulator installed on your alternator. This voltage will slowly drop off until the battery is fully charged and the electrical load is low.
Why is my alternator not showing a charge?
- Worn out brushes
- A failed voltage regulator.
- Check the wiring at the voltage regulator plug, refer to your service manual for plug connections and what they should be.
- Battery main feed line or alternator ignition charge fuse
- Diode failure in the rectifier.
- Defective voltage regulator.
- Charge lamp burnt out.
Why is my alternator charging but light stays on?
- Bad diode in the alternator.
- Bad diode trio in the alternator.
- No power to alternator ignition charge line.
Why does my battery go dead after a few days?
- Bad battery.
- Electrical system drain.
- Slipping belt.
- Alternator state of charge too low to maintain battery.
- Bad diode in alternator rectifier.
Why is my alternator over charging?
Defective voltage regulator.
My battery discharges when headlights are turned on?
- Loose or corroded battery connections.
- Bad battery.
- Bad alternator.
My headlights/dash lights dim or pulse at idle?
- Engine Idle speed low.
- Alternator output too low and not meeting electrical demand.
Why is my high output alternator not charging at idle?
- High output alternators must spin faster than a standard alternator to keep the field engaged.
- Changing the pulley to a smaller diameter will usually correct this.
Will a high output alternator or upgrade kit work with the factory electrical system?
The higher amperage produced by the alternator will not pose any problems to the vehicle’s electrical system, but too high in voltage can.
What modifications are needed when upgrading to a high amp alternator or upgrade kit?
Due to the increase in amperage, upgrading the alternator’s battery feed cable and vehicles primary ground cables is recommended.
Starter Q&A
Why does my starter just click?
- Battery voltage too low.
- Bad ground and or positive battery connection.
- Solenoid internal contacts worn.
- Starter motor brushes worn and not making contact with armature.
- Armature brush contact surface extremely dirty "contaminated with dirt, grease or oil".
Why does my starter cranks slow?
- Battery voltage too low.
- Bad ground or positive battery connection.
- Armature brush contact surface extremely dirty "contaminated with dirt, grease or oil".
Why does the starter spin and not crank the engine?
- Starter drive worn out.
- Bent or broken starter shift lever.
- Teeth missing in flywheel.
Why doesn't my starter crank when the engine is hot?
- Open circuit in solenoid.
- Open circuit in starter motor armature or field coil windings.