Alternator Rating Question

[Doug R]

Thanks the comments were very helpful and the testing as described show the voltage under load at about 1800 rpm was less that the basic battery voltage of 12.65v engine not running. At idle no load was 12.95V, Idle under load at 12.35v and at 1800 rpm the voltage was 12.52v . So I guess the alternator is suspect.

[Phx Mike]

Originally Posted by Doug R

Thanks the comments were very helpful and the testing as described show the voltage under load at about 1800 rpm was less that the basic battery voltage of 12.65v engine not running. At idle no load was 12.95V, Idle under load at 12.35v and at 1800 rpm the voltage was 12.52v . So I guess the alternator is suspect.

If you have an external voltage regulator then suggest you check those connections to ensure they are correct and secure. Not sure what setup you have but the old style arrangement has 3 wires from the alternator marked Field (usually a green wire but not always) Stator and Alternator. The Field and Stator wires run between your alternator and voltage regulator - make sure they are secure and not reversed. The Alternator wire also runs to your voltage regulator, via the starter solenoid and possibly via the ammeter if you have one. Make sure those wires are correct and secure. Your voltage regulator will also have a wire marked Ignition and it runs to your ignition switch. If all these wires look like they are routed right and not loose, then suggest you pull your alternator and take it to Autozone or O'Reillys and they can test it.