Alternator Light

[Raven31]

5.5 hours into a 7 hour x-country flight my alternator light started to flicker on intermittently .. finally it stayed on steady .. I had no other indications associated .. volts were 14.5 and amps were +2... I turned the landing lights on in the pattern and the alternator light went out . As I turned base the light came back on and on roll out i noticed 12.3volts and negative amperage draw..I turned the landing lights off and it went back to 14.5 volts and positive 2 amps... took the cowl off and found the main airplane ground had a broken ring terminal .. thought this was the culprit .. after replacing the terminal and test running the engine I still have the alternator light on with 14.6 volts and +2 amps even with both sets of landing lights and basically every electrical switch on to load test... electrical isn't my strong suit but this just doesn't make sense to me. Thoughts?

 

[Mich48041]

Check the electrical connections on the alternator. Is the regulator external or internal to the alternator?

 

[Raven31]

Plane power alt internal regulator.. i disconnected the plug on the back of the alternator and the cable and didn't see anything abnormal on those connections .. I'm just confused that the alternator is working and charging the system but the light is on.

 

[Bo1000]

Shot in the dark

Glancing at the PlanePower website, it appears that at least some of their regulators illuminate the alternator fault lamp by pulling the lamp's "negative side" to ground. So if the lamp's "negative side" wire is making contact with ground some other way, the lamp will turn on.

Another possibility is that the lamp is controlled by a Normally Closed relay that has to be energized to open the circuit to the lamp. In this case, a bad connection on the control-side of the relay would leave it closed (lamp illuminated).

Bo

 

[Raven31]

Overvoltage?

Anyone think that the light is being tripped on from over voltage? 14.6 is what I'm showing now.. just curious if anyone knows if that's the high end for plane power alternators . When I turned my landing lights on the alternator light went out for 5 seconds .. I didn't look at the volts at that time but wondered if they dropped low enough for the light to go out until the system caught back up.

 

[lr172]

Plane power alt internal regulator.. i disconnected the plug on the back of the alternator and the cable and didn't see anything abnormal on those connections .. I'm just confused that the alternator is working and charging the system but the light is on.

Several people have found this connector to fail even though it visibly looks good. It seems to be a weak point for that alternator. Suggest you replace or re-crimp.

Larry