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Plane Power Alternator Acting up


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Good evening guys,

Did a short 35 mile run and back tonight to fill the tanks.  No issues on flight out, but as I got back home and on the downwind, I noticed my Aspens both alert me they were going onto battery power, looked over and amp gauge reading no charge at bottom.  I had noticed it on earlier flight kind of dancing around a bit.  About 10 seconds later, I made a slight increase in power, and the amp gauge came back up and maxed out showing max charge.  both Aspens went of battery power.  Then just as fast as it came back, the amp gauge went back to zero all the way through shutdown, but both Aspens stayed on ship power and didnt go back to battery backup.  GTN750, radio/audio panel, transponder, engine monitor, all stayed working with no message or indications.  I do not have a volt gauge.  The alternator inop light never came on until I shut the engine off though which was weird...........Any ideas?  ill get the meter out tomorrow and follow their online troubleshoot form, but does this sound like an alternator or Voltage regualtor.

Plane sat for a series of years, so it only has 30 hours on the STC install, but was installed roughly 9 years ago.  1965 M20C with a IO-360-A3B6D upgrade

Edited by Rspencer612
forgot plane info
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Good evening guys,
Did a short 35 mile run and back tonight to fill the tanks.  No issues on flight out, but as I got back home and on the downwind, I noticed my Aspens both alert me they were going onto battery power, looked over and amp gauge reading no charge at bottom.  I had noticed it on earlier flight kind of dancing around a bit.  About 10 seconds later, I made a slight increase in power, and the amp gauge came back up and maxed out showing max charge.  both Aspens went of battery power.  Then just as fast as it came back, the amp gauge went back to zero all the way through shutdown, but both Aspens stayed on ship power and didnt go back to battery backup.  GTN750, radio/audio panel, transponder, engine monitor, all stayed working with no message or indications.  I do not have a volt gauge.  The alternator inop light never came on until I shut the engine off though which was weird...........Any ideas?  ill get the meter out tomorrow and follow their online troubleshoot form, but does this sound like an alternator or Voltage regualtor.
Plane sat for a series of years, so it only has 30 hours on the STC install, but was installed roughly 9 years ago.  1965 M20C with a IO-360-A3B6D upgrade


I got burned when a mechanic suggested my issue was an alternator problem. Replaced it with a Plane Power only to find out that the voltage regulator was the issue.

The Plane Power website has a troubleshooting tree. I’d start there.


https://planepower.aero/wp-content/uploads/2018/02/Troubleshooting-Single-Engine-Externally-Regulated-Alternators.pdf


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11 minutes ago, Marauder said:

 


I got burned when a mechanic suggested my issue was an alternator problem. Replaced it with a Plane Power only to find out that the voltage regulator was the issue.

The Plane Power website has a troubleshooting tree. I’d start there.


https://planepower.aero/wp-content/uploads/2018/02/Troubleshooting-Single-Engine-Externally-Regulated-Alternators.pdf


Sent from my iPhone using Tapatalk Pro

 

That’s the plan. Even printed it already. Just didn’t know if anyone has been down this road already!

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Check the field wiring connection and ground connection to the alternator both will cause problems.  After you are confident it is not a loose connection or other wiring issue  then start looking at voltage regulator and alternator.  I'd go with the voltage regulator since you are getting something all be it intermittent.

 

 

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2 minutes ago, Marauder said:

 


Looks like it rusted and then started arcing when it broke.


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I’m thinking you may be right!  Looks like a cut back, crimp and reinstall is in order!

 

Just now, deanders said:

Looks like it may have been loose and was arcing.

But is still tight, so I am more leaning to rust and age. It’s plane power system, but battery cable looks original.......

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19 hours ago, Rspencer612 said:

What led you to diagnosing the bad old wiring?  Voltage drop?

Verified alternator wasn’t bad. Found bad wiring. Once was enroute to Vegas and ended up with an engine failure and landed in a field while leaving the shop that rushed to get me fixed and on my way. 

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Great follow-up with pics, RS!

Check that wire, end to end prior to re-use...

In the event of high resistance down stream.... something was making the electrons want to jump...

PP thoughts only, not a mechanic...

Best regards,

-a-

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1 hour ago, FloridaMan said:

Verified alternator wasn’t bad. Found bad wiring. Once was enroute to Vegas and ended up with an engine failure and landed in a field while leaving the shop that rushed to get me fixed and on my way. 

Wow.............not good at all

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Ok guys. So cut off the end, cleaned wires, crimped new ring terminal, and put in new rubber boot protector. All is good and amp gauge back working like it used to.  I charged battery to 12.6 before taking it out and doing the ground run test. I had not looked before, but my amp gauge lives in about the 30 charging range all the time. Turn on landing light it jumps to 60 (not sure the accuracy of the factory amp gauge). But I looked at my Aspens for voltage since I do not have a voltage gauge. Running engine idle or 1700 rpm, no change, I am seeing 12.8/12.9 volts to the Aspens. This seems low......I would expect 13.4+. Old wiring with voltage drop maybe?  Any ideas?  This will be the next issue to resolve. 

9CB14943-9DA3-42A0-8426-6D4F1D185FA8.jpeg

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Before going to hard looking...

Start with the easy stuff...

Wait a minute....

weren’t we discussing looking for resistance added in already?

Time to find what is causing the odd resistance...

Start with the alternator output... see what it is sending out... (get mechanic to help)

 

Hey... wait another minute there....

Check what the battery resting voltage is... ( Is this the 12.8V you are referring to?) :)

 

Clean and ‘grease’ All the main connections...

You should be seeing near 14v while the engine is running with decent rpm... (run-up)

Expect to see corrosion on connections that aren’t working very well.

If you don’t see corrosion, it may be time to clean them anyways...

Always consult a mechanic for this type of work...

PP thoughts only, not a mechanic...

Best regards,

-a-

10EE673F-A9E1-4D0B-94B6-B2EA93531900.jpeg

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This could be a really quick test to find out where the voltage isn’t meeting expectations...

But, the level of detail regarding what voltage you are seeing under what conditions indicates you may not be the mechanic...

Not being a mechanic... remember working around moving props can be extra dangerous...
 

:)

Best regards,

-a-

 

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There’s a bunch of us that have been through low voltage with the older airplanes.  Most of it is old wiring and corroded connections.  If you go through the troubleshooting guide from PP or Zeftronics, you can probably isolate the problem.  I isolated mine to a worn circuit breaker feeding the voltage reg, worn master switch (field wire runs through the master), and to the field wire dropping some voltage.  I’ve fixed 2 of theses things so far and it’s definitely helped.  Replacing the field wire is definitely a good thing once in a while but it’s a pain because it runs From the VR back through the master switch and then to the alternator.

 

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I have a plane power system alternator and their voltage regulator accompanying it. I will run through the diagnostics on it as it’s all engine off master on. I’m not comfortable being up there with prop running, so if that’s needed likely a trip to the mechanic. And he is consulted on all my work, and handles my sign offs.

him and I will be doing owner assisted annual starting 8/1 when it becomes a pumpkin, so I wonder if I can live with 12.8V until then.........

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54 minutes ago, carusoam said:

Before going to hard looking...

Start with the easy stuff...

Wait a minute....

weren’t we discussing looking for resistance added in already?

Time to find what is causing the odd resistance...

Start with the alternator output... see what it is sending out... (get mechanic to help)

 

Hey... wait another minute there....

Check what the battery resting voltage is... ( Is this the 12.8V you are referring to?) :)

 

Clean and ‘grease’ All the main connections...

You should be seeing near 14v while the engine is running with decent rpm... (run-up)

Expect to see corrosion on connections that aren’t working very well.

If you don’t see corrosion, it may be time to clean them anyways...

Always consult a mechanic for this type of work...

PP thoughts only, not a mechanic...

Best regards,

-a-

10EE673F-A9E1-4D0B-94B6-B2EA93531900.jpeg

Battery showed 12.6V directly connected to it before I started. I didn’t see what aspen showed prior to starting. But I started it and then found the Aspen page showing voltage and it shows 12.8v. So alternator must be providing some power as it was increased from the 12.6 the battery had prior to hitting the start switch. 
 

it may very well be in the main alternator cable I fixed. When I cut it back, it had corrosion, I cleaned it to shiny copper before repairing. Who knows what the other side and rest of the cable in the sheath looks like.........

 

Out with the Meter and on the hunt I go!

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One thing for sure...

Alternators put out some power during ground ops.... better than a generator...

Realistically a good amount of power will rely on more than idle speed...

This is a bit Of a pain While taxiing... as the Mooney likes to go fast even while on the ground...  :)
 

For my ship... the alternator red light comes on unless a few more rpm are added.... but, this would require dragging the brakes to keep from going 20+KTs.....

Best regards,

-a-

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5 minutes ago, carusoam said:

One thing for sure...

Alternators put out some power during ground ops.... better than a generator...

Realistically a good amount of power will rely on more than idle speed...

This is a bit Of a pain While taxiing... as the Mooney likes to go fast even while on the ground...  :)
 

For my ship... the alternator red light comes on unless a few more rpm are added.... but, this would require dragging the brakes to keep from going 20+KTs.....

Best regards,

-a-

Wait, you taxi slower than 20kts? 
 

IAS, TAS or groundspeed?

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19 minutes ago, Jeph357 said:

Would all taxi speeds be considered ground speed?.....

Well depends... if someone accuses me of taxiing to fast in a tailwind, I might mention the airspeed indicator showing zero!

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18 minutes ago, Ragsf15e said:

Well depends... if someone accuses me of taxiing to fast in a tailwind, I might mention the airspeed indicator showing zero!

I've been accused of taxiing fast i just told him your a piper driver anything a Mooney is doing looks fast to you

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