T

Tram

Well Known Member
Hey guys-

Been having some intermittent issues with our alternator..

Normally, I show around 13.6v on the voltmeter while the plane is running and alternator is selected.

Now I am running around with ~12.8v showing.. Occasionally, it'll jump up to 13.6v..

If I turn on everything - and I mean everything - sometimes I can coax it to picking up the load..

Is this a dying alternator? Anyone have any ideas?

Thanks

Jeff
 
Yup, it's dying.

That's a typical scenario. Either you have intermittent wiring somewhere, or the alternator is losing "oomph". Having gone through a number of them lately (3 in the last year), that's usually what happens to me.

It gets weaker and weaker, output voltage drops (usually due to worn brushes) and then it may or may not fail completely.
 
Worn brushes would be a possibility. What type of alternator do you have and how many hours in service does it have?
 
Weak alterrnator

For several weeks I experienced the same symptoms - weak alternator, sometimes fallng off the line for no apparent reason. Bought and installed a new Plane Power alternator, with no improvement. I finally decided to rewire all of the alternator system, and in the process found the terminal screw on the alternator circuit breaker loose! Since tightening the screw on the terminal, I have had no further problems.

Craig
 
In addition to loose connections....

Look for connector lugs that are not properly squeezed. IOW, a lousy connection.

Look what happened with these improperly squeezed wires from Vans. They pulled apart!!

battleadfailure1.jpg


Barry
 
i had a similar ............

problem. i traced the large output wire from the alt to the breaker panel and found it to be 1/4 turn loose. that did it. turbo
 
MrNomad said:
Look for connector lugs that are not properly squeezed. IOW, a lousy connection.

Look what happened with these improperly squeezed wires from Vans. They pulled apart!!

battleadfailure1.jpg


Barry
Click to expand...

The vans battery connector lugs that came with my late 90's electrical kit looked cheap and nasty to me so I soldered all of them as well to stop that from happening. :)
 
Last edited:
What voltage is too high?

On a recent trip back from Delaware to Louisiana I noticed my voltage output fluctuating during climbout from 12.8v to 15.6v After about ten minutes of this, it eventually settled down to 15.6v and stayed solid for the remainder of the 2.9 hour trip.

The alternator is Van's 60 amp with internal regulator. Any thoughts on the upper limit for voltage? In the meantime I will be checking connections and even if I don't find anything I will pull the unit to see what's going on and get it repaired. But I'm not sure it's broken yet.
 
Bob Gordon said:
On a recent trip back from Delaware to Louisiana I noticed my voltage output fluctuating during climbout from 12.8v to 15.6v After about ten minutes of this, it eventually settled down to 15.6v and stayed solid for the remainder of the 2.9 hour trip.

The alternator is Van's 60 amp with internal regulator. Any thoughts on the upper limit for voltage? In the meantime I will be checking connections and even if I don't find anything I will pull the unit to see what's going on and get it repaired. But I'm not sure it's broken yet.
Click to expand...

15.6 would make me nervous - if that is a true reading Bob - do you have only a single way to see the voltage? You might stick a DVM somewhere in the circuit and see what it says, just to confirm you don't have measurement error. I changed my alternator a few years ago because it did about the same thing - waivering voltage that settled out high. (And I had four meausrements telling me that it was real.)

Paul
 
Bob, when my alternator started making 17 + volts

I ask Vans about it and they sold me a new regulator for it. It fits right on the back end of the alternator.

Kent
 
Recollections from the past

Once upon a time my best buddy had an alternator and starter rebuilding business in Brooklyn NY. When I came into NY I used to visit and help out.

I recall that the high side of an alt was approx 14.2 or 14.4.

My guess is that 15v and higher will lead to premature battery failure, overheating of the battery, and other events not exactly suitable for an airplane.

At the very least, run the lites and all devices that use electricity when you see high voltage to reduce the potential for fire and other unpleasant outcomes.

Also look for loose connections and corroded connections. Better yet, quit flying until you resolve, remove the alt (and reg) and take it to a shop for testing. Virtually any decent alt rebuilding shop can simulate a load and tell you if the alt is the prob. Conceivably, the internal reg can be the issue.

My 2 cents.
 
I'm gonna be out at the airport tomorrow, I'll check it out... You know, I recently loosed the ground nut while working on the plane, could be the issue - it is sorta when the issue started as best I remember..
 
High Voltage Alternator - Follow Up

I wanted to post results to my issue with Van's 60 amp alternator high voltage (steady 15.6 v). It failed a bench test and the local auto electric shop replaced the regulator P/N IN221. He also replaced the brushes as they were a bit more than half worn at 450 hours time in service. All this while I waited, for $45. A happy camper.

I should mention no one - NAPA, Advance Auto, Auto Zone, O'Reilly's - carry the original P/N alternator 14684. I would have had to chance it with a different P/N that looked like mine for $120 exchange. Didn't want to go that route. Also, Joe Blank at Van's confirmed they do not support or carry parts for 14684 any more.
 
Bob Gordon said:
I should mention no one - NAPA, Advance Auto, Auto Zone, O'Reilly's - carry the original P/N alternator 14684. I would have had to chance it with a different P/N that looked like mine for $120 exchange. Didn't want to go that route. Also, Joe Blank at Van's confirmed they do not support or carry parts for 14684 any more.
Click to expand...

I bought a new (reman) Dura-Last alternator from Auto Zone a year or two ago; it was a direct replacement for the stock Vans 14684... new p/n is 14824. Works great and only 100 bucks.
 
45 bucks - smokin deal!

Bob Gordon said:
It failed a bench test and the local auto electric shop replaced the regulator P/N IN221. He also replaced the brushes as they were a bit more than half worn at 450 hours time in service. All this while I waited, for $45. A happy camper.
Click to expand...

Thanks for the reply Bob. It was back in the 80's when my experience with alternators occurred. Apparently, technology has not changed that much.

Barry
 
You must log in or register to reply here.