Alternator Amps

[BravoWhiskey]

I have had an alternator issue I have been digging into and finally have some better understanding of why i was having an issue.  My alternator should putting out 130amps...  i was not understanding this.  I knew there was the dual 70's, and the 100 main with 20 as backup.  It seems I have 130 with 20 backup.  Anyone else have this setup?  I was unable to find this in any of the books.  My alternator was "only" putting out 95amps.  The alternator is being replaced now and making sure I have no other gremlins in there that caused the alternator to start failing.

[FoxMike]

i do not understand the question.  Standard configuration is 2 70amp alternators.  If you have air-conditioning one of the alternators may have been removed for the compressor and a larger alternator installed to provide extra power for the air conditioner.  Someone else may come along who knows for sure.

[N201MKTurbo]

How do you know the alternator was only putting out 95 amps? I can’t think of any good way to test that on the plane.

[BravoWhiskey]

@FoxMike you are correct. The documents for the Air Conditioner state the replacement of the dual 70amp with a 70 and 100amp and 20 amp backup... i think.  

@N201MKTurboIt was removed and sent out for testing.  

In my case i seem to have just the 130amp and the 20 amp backup.  Not the other 70amp...

[Niko182]

In flight I doubt your amp usage would be more than 30 or 40 amps. I've very rarely seem my alternator put more than 40 amps out, and I have a 150 amp alternator. 

[BravoWhiskey]

I dont know the load of all the systems.  But between G1000, AirCondition, TKS, Autopilot, non LED lighting, I wouldn't be surprised if it exceeded some standard draws.  All that aside I am just trying to learn more about the plane.  I was surprised that I had the one 130amp alternator.

Either way, I'm having it replaced as I dont want to see this again when flying... it's a little uncomfortable.

[LANCECASPER]

 

On the Bravos I owned they all had two 70 amp alternators but I understand that on the G1000 airplanes that might be different. The IPC says that when you have Air Conditioning you have one 130 amp (ES4019) and one 70 amp (ES4009LS) @Danb would probably know.

 

The Parts catalog does mention a B & C 410 standby alternator and regulator, but in the notes it says not used. Maybe these are used on the G1000 Bravos on the back of the engine where a vacuum pump would have gone. @Danb

But before you start replacing alternators I would do a little more investigating. Are you sure it's not your voltage regulator? How old are your batteries? Gill or Concorde?

[BravoWhiskey]

This detail is helpful, thanks.  And it seems to be the setup I have with the 130 and 70 amp alternators.  The batteries (concorde) and voltage regulators were tested and all seem good.  The 130amp alt seems to be the week link.  The MSC is testing all of the systems to see if there is any other underlying issue that caused the alternator to go bad or if it just started to fail on its own.  

[Danb]

I believe two 70 Amp alternators 

[carusoam]

Alternators are amazingly reliable creatures…

But, sometimes… their bridge loses a diode or two…

Losing a diode also causes whining in your headset that is rpm dependent…

 

First know what alternators you have… and how to test them in flight…  you probably won’t see maximum amperage unless the ship’s systems are drawing a lot of power…

 

Generators have brushes that wear, and often leave wear marks and crummy contact issues after that. (Unrelated)

 

The biggest failure often found… is related to the field wire… this wire instructs the alternator what to do…

When the field wire breaks, because of vibration… the alternator gets blamed…  seriously check your field wires at both ends…

 

Then there is the all important dual voltage regulator… that is on the other end of the field wires… these have been known to cause a hassle… and getting them OH’d is a possibility….

 

All stuff I learned around here…

Best regards,

-a-

[BravoWhiskey]

This particular alternator is the devil.  It seized up causing a belt to get chewed up, but the pulley spun freely on the ground.  So we thought it was just a bad belt.  Then the replacement belt flipped upside down.  Again thought it was an belt issue, or alignment... it wasn't.  The alternator had bad bearings causing it to seize up under load.  So it was overhauled.  Despite the overhaul the field is not working correctly (this issue being internal to the alternator and not a external wire issue) and the output being 95 vs 130 basically made a replacement the easiest decision for me.  

I hope to have this all wrapped up in another 2 weeks.  I only have about 12 hrs on a fresh overhauled notor and I am itching to get some good trips booked.  

 

[Danb]

That blows, my Bravo has about 1100 hours, I changed it at about 500+ hours.

Wish you good luck with the new one

 

DB

[BravoWhiskey]

We’ll it seems this issue may have finally been resolved.  The 130 amp alternator was actually putting out 85 amps, there was some faulty wiring that did not match Mooney schematics, and the chewed up bearings… Weber Aircraft and Lancaster Avionics (both located at KLNS) were great with advising me of each issue as they diagnosed the aircraft.  Now I am waiting for them to reinstall the STEC55x which has been another ongoing issue where the elec trim fails.  Turns out there was no lubrication whatsoever on the tail.  The extra friction was causing the servos and computer to fail.  In the logs, it seems the computer and servo had been addressed numerous times but never the lubrication.  
 

 

[BravoWhiskey]

FINALLY!  It's been 51 weeks since I picked this plane up, overhauled the engine and dealt with this alternator issue and AP/Elec trim problem.  I picked her up today and what a notable difference with all the systems working properly.  Unfortunately I had to work today... so I only got about 30 minutes in.  As I mentioned above Weber and Lancaster were great to work with so I want to throw  them a plug here.  Can't wait to finally get up this weekend...

Edited February 5, 2022 by BravoWhiskey

[carusoam]

Great pirep for Weber!

-a-