Alternator issue...retread

Timbeck2

Timbeck2

Final Approach
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Timbeck2
Okay, recently I took a trip to Texas and landed with a discharged battery. Didn't notice with the ammeter installed. Found a loose wire to the alternator and it fixed the problem or so I thought. I installed a new ammeter which has warning lights for discharge and overcharge along with a switch for amps and volts. (thanks Spike)

I took a trip up to Flagstaff Friday and noticed a discharge light on the way back. I reset the alternator via the master switch and it worked for a couple minutes and then the discharge light came back on. I turned the alternator master back off and left it off for 5 minutes. Then I turned it back on, the discharge light went out but came back on after about 5 minutes. All in all from Payson to Tucson (1.4 hours) I must have reset the alternator about 10 times.

After I landed, I checked the connections to the alternator which seemed fine. The voltage regulator is new. Of course I'm going to have a mechanic check it out but what does it sound like to the A&P's here or anyone else who've had a similar problem?
 
Without seeing the airplane and going off what you say has been done to it, I'd guess bad brushes in the alternator. You'll probably be repairing or replacing the alternator.

If that is true, I'd look into a Plane Power conversion. They're nice, and they're new rather than being old and worn out.
 
My Cherokee had a separate over voltage monitor relay, in series with the voltage regulator, that had to be de-energized to reset it after it had tripped (alt. half of the master switch off and back on). It was tripping once because of a loose field wire on the alternator. You have already checked that. A worn out field slip ring brush in the alternator could have the same effect.
 
I already suspected that the alternator was the one on the plane when it left the factory in 1969. I've got the Plane Power AL12-C60 in the cart anticipating what the opinions were going to be. Still going to have a mechanic check it out for sure.
 
Reset fix sounds like bad reg to me, but what do i know, im a car guy. I know u said reg is new.
 
If the airplane has an overvolt sensor, make sure all its connections are tight. A bad ground connection (the black wire from the sensor) will cause the alternator to trip off frequently.

The Plane Power is not always a plug-and-play affair. There are some wiring changes that, at shop rates, could make it expensive. And it's still just another alternator after all, with slip rings and brushes and diodes, all the same as the old ones.
 
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...The Plane Power is not always a plug-and-play affair. There are some wiring changes that, at shop rates, could make it expensive. And it's still just another alternator after all, with slip rings and brushes and diodes, all the same as the old ones.
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Noted. Weight was a consideration as well. In my CG forward Cherokee, I need all the help I can get.

edit: saw this in the review section: "A good alternator, but be careful! If you have a narrow deck Lycoming you will need to order a special bracket from Plane Power."

I have an O-320....narrow deck?

The bracket is included but I don't know deck about deck.
 
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Narrow deck cylinders will have Allen bolts retaining them to the case. Wide deck has standard nuts IIRC.
 
What model year Cherokee? The Plane Power alternators are a plug and play affair for the later model Cherokees, no wiring alterations needed. You'll just be limited to 60 amps rather than the full 70 amp output.
 
Graueradler said:
My Cherokee was a 71. Chrysler alternator. Changing the field brush was no big deal.
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Did you pull the alternator or did you do it with it installed on the engine? With the cowling on? Through the exhaust pipe? :D
Seriously, curious. I think you "should" be able to do it if you pull both top and bottom cowling. Never had to do it myself so I ask for the future.
 
BigBadLou said:
Did you pull the alternator or did you do it with it installed on the engine? With the cowling on? Through the exhaust pipe? :D
Seriously, curious. I think you "should" be able to do it if you pull both top and bottom cowling. Never had to do it myself so I ask for the future.
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Sorry, it has been so long ago that I don't remember.
 
BigBadLou said:
Did you pull the alternator or did you do it with it installed on the engine? With the cowling on? Through the exhaust pipe? :D
Seriously, curious. I think you "should" be able to do it if you pull both top and bottom cowling. Never had to do it myself so I ask for the future.
Click to expand...

You can do it with the alternator installed.
 
Timbeck2 said:
1970 Cherokee 140
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Mine was a '69 Cherokee 140. The Plane Power alternator is a direct swap.

As was mentioned, you can try brushes first if you'd like, to save a few bucks. I did that and it worked for a while, but failed again. I got tired of screwing around with it and just put the Plane Power on.
 
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