Thread: Alternator Problems

Hi All

I have just installed a new alternator V8 3.5 petrol series one,it is charging at approx 14.4 Volts , however the charge light stays on dimly at idle and brightens up when motor revs increase . Battery is charged and vehicle is running well . The old alternator caused the charge light to come on with the iginition off and was only putting out about 6 volts and battery was flat, have i missed something simple.
Also the alt light flashes in sympathy with the indicators.
Any assistance would be appreciated.

Ta

Martyn

Sounds like a high resistance somewhere.

1) Turn on lights demister etc, you want to draw a lot of current.
2) Measure the voltage between the alternator GND and the engine block - should be close to 0v.
3) measure between the alternator GND and a metal point on the body - should be clost to 0v. If it's higher then check the engine earth strap.
4) check the wire between the alternator +ve and the battery - should be low voltage perhaps 0.1-0.3v. if it's higher or it's smoking then it is damaged.

That should find most issues - just keep measuring voltages until you find the drop.