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Alternator offline


Bartman

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On a recent flight I noted the voltage light was illuminated about 2000 ft into the climb. I confirmed by ammeter and on the JPI which read 11.9 volts best I can remember.  I pulled the field breaker and pushed it back in and had no further problems.  Before the return flight I checked the belt which showed no sign of slippage, and it was at its normal tension.  However, on climb it happened once again exactly as described above, and charged normally after reset.  Battery is less than a year old and cranks great, voltage regulator changed about 5 yrs ago and all I remember was it was waaaay expensive.

Its time for annual inspection and I'll tell the IA about it, but I was wondering what is the likely cause ? Corrosion at one of the connections, battery, alternator, voltage regulator?

 

 

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5 hours ago, Bartman said:

On a recent flight I noted the voltage light was illuminated about 2000 ft into the climb. I confirmed by ammeter and on the JPI which read 11.9 volts best I can remember.  I pulled the field breaker and pushed it back in and had no further problems.  Before the return flight I checked the belt which showed no sign of slippage, and it was at its normal tension.  However, on climb it happened once again exactly as described above, and charged normally after reset.  Battery is less than a year old and cranks great, voltage regulator changed about 5 yrs ago and all I remember was it was waaaay expensive.

Its time for annual inspection and I'll tell the IA about it, but I was wondering what is the likely cause ? Corrosion at one of the connections, battery, alternator, voltage regulator?

 

 

When were the brushes last changed?

Clarence

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I had a similar issue about a year ago.  The only time the low voltage light would flash was in climbs.  I had a mechanic look it over and he assured me it was the alternator so we replaced the alternator and I still had the problem.  Continued troubleshooting and determined that it was only a loose field wire.  Tightened it and so far have not had any issues since....

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I had a different issue.  The overvoltage light would come on every once in awhile.  Each time it would re-set by just turning the master off, then back on.

Maybe my "fix" will work for you.

Because I was afraid of getting stranded with no alternator ouput, I bought a brand new Zeftronics regularot and put it in my baggage compartment.  That's the last time the over-voltage light came on.  The Zeff is still in my baggage compartment.  :lol:

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  • 2 years later...
On 12/17/2015 at 10:52 AM, lukejb said:

I had a similar issue about a year ago.  The only time the low voltage light would flash was in climbs.  I had a mechanic look it over and he assured me it was the alternator so we replaced the alternator and I still had the problem.  Continued troubleshooting and determined that it was only a loose field wire.  Tightened it and so far have not had any issues since....

I am having the exact same problem. While I was doing night currency landings the over voltage protection light (from a Zeftronics voltage regulator) was coming on during the climb. The JPI volt/amp display showed a slight discharge on the ammeter and voltage drop back to 11V (and at one stage 10V which was pretty strange given the battery still had 12.2V after shutdown). The alternator came back with a field breaker reset on downwind. I repeated this 3 times (partly to troubleshoot, partly to get the night currency...) with reduced electric load each time. The same thing happened each time.

A few weeks prior my A&P looked at the alternator as a similar thing was happening in cruise with very little electric load. He found / fixed a loose ground wire and the aircraft flew fine for the next 5 flights before this happened.

I've visually checked all of the wiring to the alternator and the voltage regulator and it looks fine. I'm wondering if the Zeftronics might have an internal fault or whether the loose ground wire might have cooked the alternator?

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  • 3 months later...

I had this problem this morning while on the ground.  I tried a run up and at 1900 rpm still discharging and the JPI indicated 11.8 then a few minutes later (went thru some preflight checks) 11.6.  However, when I pulled and reset the alternator field switch it did not fix the problem.  I'm stumped and waiting to hear back from my local IA.

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ap,

are you ready to do the problem solving 101..?

1) field wires have a tendency to break their connectivity...

2) which voltage regulator do you have...

3) what alternator do you have...

4) Alternator belts have a tendency to get loose enough to not allow charging...

Many easy things to check into...

PP thoughts only, not a mechanic...

Best regards,

-a-

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While doing the research.... consider this input...

https://mooneyspace.com/search/?&q=Light weight alternator &search_and_or=and&sortby=relevancy

And the other keyword... Zeftronics VR.

If somebody already put the lightweight alternator in, and the zeftronics VR...

Most likely a broken wire connector, or loose belt...  there is an actual torque measurement for tightening the belt..

Check the logs to add up the hours on your existing alternator and voltage regulator. They could be original...

Are you hoping for a low cost fix, or a good fix?

Best regards,

-a-

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I ended up AOG twice with my F due to alternator wires failing. After one of the repairs, I experienced an engine failure that landed me in a field -- whether or not related, Occam's razor makes it seem likely. 

Get it fixed correctly. If your wires are old and one failed, have all of the ones that are connected to your alternator replaced. If the field wire failed, then the others are not far behind. If it's the alternator or brushes, go ahead and get a Plane Power installed. 

For want of a nail the shoe was lost.
For want of a shoe the horse was lost.
For want of a horse the rider was lost.
For want of a rider the message was lost.
For want of a message the battle was lost.
For want of a battle the kingdom was lost.
And all for the want of a horseshoe nail.

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7 hours ago, apenney said:

@carusoam  I'm not sure which regulator or alternator I have.  The belt feels the same as it has in the past.   Will take a closer look at things tomorrow.  Thanks for the suggestions. 

@RobertGary1 I hadn't thought of going to lower RPM.   Will look into that too.

If you can see the alternator pulley, clip 2 paper clips together making a 2 link chain.

Turn the master switch ON and alternator field switch ON if your plane has one. Leave the mags OFF.

Go to the front of the engine, while holding the upper paper clip the lower one should be drawn to the pulley.  This magnetism tells you that the field circuit is providing field power.  

No magnetism, no field power.  Open the left side cowl and look for broken field wires. 

Clarence

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1 hour ago, M20Doc said:

If you can see the alternator pulley, clip 2 paper clips together making a 2 link chain.

Turn the master switch ON and alternator field switch ON if your plane has one. Leave the mags OFF.

Go to the front of the engine, while holding the upper paper clip the lower one should be drawn to the pulley.  This magnetism tells you that the field circuit is providing field power.  

No magnetism, no field power.  Open the left side cowl and look for broken field wires. 

Clarence

I have a breaker labeled alternator field that I can pull and reset.  Is there a switch somewhere else that is the actual "alternator field switch"?

Also, I don't know if this might be relevant but last week I had a local avionics guy look at my transponder wiring because it has been getting an intermittent signal from it's "position source" which in my plane is the Garmin 430W.  I wonder if there a switch that could have been inadvertently turned off?   

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I vote bad field wire or loose B Plus wire at the alternator.   Mine wire fell out of the lug connector when I took the alternator off to get to the fuel pump.  Your plane probably came with an Alternator.  You probably have this regulator up on the top outside co pilot side firewall.  Along with this interference filter

IMG_20180217_151853.thumb.jpg.f2dd64f352471f317c9a2919460a5257.jpg

IMG_20180217_151839.jpg

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Master, alternator, and avionics have a tendency to be mounted next to each other in order...

Sometimes split switches are used when adding a CB/switch... takes up less space...

If you have a CB for the circuit, sounds like they didn’t want a switch at the time...

PP thoughts only, not a mechanic...

Best regards,

-a-

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9 hours ago, apenney said:

I have a breaker labeled alternator field that I can pull and reset.  Is there a switch somewhere else that is the actual "alternator field switch"?

Also, I don't know if this might be relevant but last week I had a local avionics guy look at my transponder wiring because it has been getting an intermittent signal from it's "position source" which in my plane is the Garmin 430W.  I wonder if there a switch that could have been inadvertently turned off?   

Some airplanes have a split master/alternator field switch, others have a single switch with two sets of contacts, one master, one alternator, sounds like you have that version.

Some switches have push on type electrical connectors which also come loose making for no alternator output.

Clarence

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Well it turns out that the alternator was the culprit.  Installed an overhauled one.    But....on my first flight noticed a few things:

1. After about 15 minutes of cruise flight I noticed a slight almost imperceptible drop below zero on the ammeter and the battery volts showing 13.8 (previously 14.3).  I turned around to my homefield and landed.  Near idle the ammeter was back in the middle again

2. My landing light wasn't working

3. The ram air control was opening on its own at anywhere above 100mph or so. 

Landed.  With the engine running mechanic pulled the alternator field circuit, ammeter showed discharge, then pushed it back in and there is 14.3 and positive ammeter again.  Couldn't reproduce anything on the ground.  Then the shop opened the cowl up.  They think they unintentionally loosened the ram air control previously when clearing some corrosion during the alternator installation.  No slippage of the control cable was seen so they tightened  the nuts up a bit.  Regarding the landing light bulb,  it is secured based on the tension of a steel wire clip component (I don't know the proper term for the piece but it springs open into a secure fitting) that may have been bumped when putting cowl back on.

Haven't flow yet since the adjustment so have yet to reassess the ram air control but the landing light is working again. 

Is it unusual to see a temporary drop in the amount of charge (or even a slight discharge state) that is allowed to feed the battery? 

A view of my ram air control hardware:

image.thumb.png.5cdea1f045fe043c4ef5c80951eb2bb9.png 

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I have a question about the ammeter and how it works.  Background - been having radio issues, light problems, battery issues, etc.  Turns out the voltage regulator was set to put out 13 volts.  I mention this only because the ammeter would only show a tiny discharge with the master on and engine off and a tiny charge with engine on.  It wasn't until I had a voltmeter hooked to the buss bar looking at the radios that I realized the voltage was too low.  How should the ammeter have helped in this case?

Ever since setting it to 14.2 volts, no more problems.

 

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Ammeters are technically a volt meter placed across the shunt...

The shunt is a calibrated resistor that creates a voltage drop, that is measured by the ammeter...

The ability if the system to show fine detail  is not very much with analog needles...

But, when the charging system dies, the needle heads to the left in a way that looks pretty unfamiliar...

upgrades include digital instruments and solid state VRs...

The original VR may be made of sticks stones and springs... A little difficult to set..

The amount of charge is based on the voltage supplied to the field wire....

key word to look for on the VR... electro-delta or Zeftronics...

PP thoughts only...

Best regards,

-a-

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15 minutes ago, carusoam said:

Ammeters are technically a volt meter placed across the shunt...

The shunt is a calibrated resistor that creates a voltage drop, that is measured by the ammeter...

The ability if the system to show fine detail  is not very much with analog needles...

 

The original VR may be made of sticks stones and springs... A little difficult to set..

The amount of charge is based on the voltage supplied to the field wire....

^ ^ ^ ^

One of the best, short descriptions of the charging system and ammeter I've seen.

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