Tell Tale signs of a dying alternator?

Tram · #1 06-11-2010, 07:23 PM

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

N131RV · #2 06-11-2010, 07:33 PM

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.

cfiidon · #3 06-11-2010, 07:50 PM

Look at the Zeftronics document and their notes on troubleshooting.

http://www.zeftronics.com/documents/pit/R1510N-PIT.pdf

A poor connection or bad ground can also cause such troubles.

Read this through, and perhaps check some of the items they mention. Even if you don't have their regulator, the tips may help.

Don

airtractor8 · #4 06-11-2010, 07:58 PM

Worn brushes would be a possibility. What type of alternator do you have and how many hours in service does it have?

gear1 · #5 06-11-2010, 09:34 PM

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

MrNomad · #6 06-11-2010, 10:06 PM

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!!

Barry

turbo · #7 06-12-2010, 06:49 AM

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

airtractor8 · #8 06-12-2010, 07:16 AM

Quote:

Originally Posted by MrNomad

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!!

Barry

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.

tomdubes · #9 06-15-2010, 05:56 AM

Loose belt can cause low output too.

Bob Gordon · #10 06-16-2010, 05:14 AM

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.