Electrical issue help please

[JoshMan]

Hey, yall.  I need some help! I have 1969 E  model

So I just had a bunch of avionics work done including a g5, edm900, gtx345, metal panel, new DG installed.  I picked up two weeks ago and everything ran great for a couple of days.  I went to fly one night last week and as I was putting my gear down the OVR volt light came in and the 900 was showing 12.1 volts and -4 amps.  Typically runs at 13.8/+4

Messed around with it for a day and noticed water was low in battery.  Filled it and it ran fine over to Peoria where I have maintenance done.  I had them put a new concorde 35A battery and also they replaced the starter.

I have flown it a couple times since then and the one thing that has been different is the amps have been fluctuating from 2-4.  Tonight I was doing commercial maneuvers.  Went to put my gear down, and, once again the OVR volt light comes on and 12.1/-4.  I turned all electronics off and it went to 12.5/+1.  When nav and landing lights came on it dropped to -6

Any thoughts would be much appreciated I have to get this thing to willmar this month for the annual

[Andy95W]

Let me guess- you have an alternator conversion?

[Dream to fly]

sounds like a charging system issue.

[Yetti]

Check field wires on alternator.   You have to take the alternator off to the to the starter bolts.   Check crimp terminals.

[Andy95W]

Actually, this is reminiscent of an issue I had about 25 years ago that is a gear issue.  

I'll wait until hearing if he has an alternator. 

[JoshMan]

I do have an alternator

 

[orionflt]

you keep saying over voltage light, sounds more light its an alternate inop light. did you do the plane power conversion?

how old is the alternator?

what Regulator do you have?

do you have a field switch?

have you cycled power to the field when this happens?

possible problems:

no/ intermittent field voltage

Regulator failing

alternator failing

or as stated above loose or bad wiring

 

Brian 

[JoshMan]

Just now, orionflt said:

you keep saying over voltage light, sounds more light its an alternate inop light. did you do the plane power conversion?

how old is the alternator?

what Regulator do you have?

do you have a field switch?

possible problems:

no/ intermittent field voltage

Regulator failing

alternator failing

 

Brian 

I have an annunciator light that reads "OVR volt"

The alternator was overhauled in 2008

I honestly have no clue which regulator I have.  I will do some more research and get back to you

[HRM]

Just now, JoshMan said:

I have an annunciator light that reads "OVR volt"

 

I believe that light is activated by the reg. It's next...

[JoshMan]

Just now, HRM said:

I believe that light is activated by the reg. It's next...

What do you think the link with dropping the gear and the drop in voltage/amps is?

[Andy95W]

I had the exact same problem in 1992 when I bought my first Mooney, an M20C with electric gear and an alternator conversion.  Every so often, lowering the landing gear would knock the electrical system offline by tripping the overvoltage relay.  Never on gear retraction or any other scenario, only gear extension.  It was easily reset, but annoying.

I was stationed in Texas at the time so on a day off I flew down to Kerrville and parked at the factory.  A nice older guy came and escorted me around.  He said he liked my airplane, the M20C was always one of his favorites.  He asked how I liked it and I said great, except I have this weird electrical problem and described it to him.

He asked if I had an alternator conversion, and when I said yes, he said that they had a similar problem in the mid-70s when they were creating the M20J 201.  (I was talking to Bill Wheat, which I didn't realize was a very big deal until much later.)

He said the problem was that when the landing gear drops, sometimes gravity (or turbulence) will push the gear down which actually drives the landing gear motor, which then acts as a generator and can throw some crazy voltage into the system.  This isn't a problem until you have an alternator which includes an overvoltage relay.

He reached into his desk drawer and pulled out a couple of small diodes and explained where to install them into the electrical relay junctions of the landing gear system.

I updated my maintenance manual with a note saying it was modified IAW factory representative Bill Wheat and the problem went away.

[HRM]

Just now, JoshMan said:

What do you think the link with dropping the gear and the drop in voltage/amps is?

Well, I am guessing you have electric gear, which I <personally> consider to be an abomination, and this is one reason why.

It very well could be that your gear drive motor is going south, and so drawing more current, or that it needs lube because it is straining.

[orionflt]

the reason I believe it is an alternator fail light is because of the voltages you are seeing when it comes on, if it is only coming on when your gear motor is running there may be a ground issue 

[Andy95W]

BTW, when I bought my current M20C, I checked the logbook.  Bill Wheat did the first flight in my current airplane.

 

[JoshMan]

1 minute ago, Andy95W said:

I had the exact same problem in 1992 when I bought my first Mooney, an M20C with electric gear and an alternator conversion.  Every so often, lowering the landing gear would knock the electrical system offline by tripping the overvoltage relay.  Never on gear retraction or any other scenario, only gear extension.  It was easily reset, buy annoying.

I was stationed in Texas at the time so on a day off I flew down to Kerrville and parked at the factory.  A nice older guy came and escorted me around.  He said he liked my airplane, the M20C was always one of his favorites.  He asked how I liked it and I said great, except I have this weird electrical problem and described it to him.

He asked if I had an alternator conversion, and when I said yes, he said that they had a similar problem in the mid-70s when they were creating the M20J 201.  (I was talking to Bill Wheat, which I didn't realize was a very big deal until much later.)

He said the problem was that when the landing gear drops, sometimes gravity (or turbulence) will push the gear down which actually drives the landing gear motor, which then acts as a generator and can throw some crazy voltage into the system.  This isn't a problem until you have an alternator which includes an overvoltage relay.

He reached into his desk drawer and pulled out a couple of small diodes and explained where to install them into the electrical relay junctions of the landing gear system.

I updated my maintenance manual with a note saying it was modified IAW factory representative Bill Wheat and the problem went away.

Very interesting.  I hope this is the issue. It's just odd that it would just now happen.  Has been running perfectly for over a year now.   I guess the gear motor could be going bad as HRM alluded to.

[Andy95W]

Mine was intermittent for a few years and would come and go without any rhyme or reason.  Eventually I installed a voltage warning light that would be my "reminder" to reset the alternator. Then I went to the factory and talked to Bill.

[JoshMan]

OK. Thanks, guys.  I will get to the airport this weekend and do some work.  Will let you know what I find.

Josh

[carusoam]

Going on the record...

1) One battery seems to have boiled away some water...

2) The next battery has not solved the issue...

3) The light on the instrument panel is claiming over voltage... that would explain some missing Battery water.

4) there is no knowledge of a Zeftronics regulator being installed.

5) whatever voltage regulator is in there now isn't keeping the voltage up.

6) -4 amps indicated the battery draining, the alternator isn't being asked to be on...

7) Volts around 12.1 looks like the battery is draining.

8) lots of added new electronics probably has little to do with a VR challenge other than it is part of the system and may have gotten jostled along the way...

9) lowering the gear is just putting a big load on a alternator that isn't working properly.

10) if it really is an overvoltage situation like the panel light is claiming... stop flying it, your new electronics are at risk...

11) You can read up in your POH what the OVR voltage light really means, what causes this lamp to be lit...

PP ideas only.  But it looks to me that the voltage regulator isn't working as expected.  Definitely get on it before another battery gets ruined and electronics get burnt...

Sorry if I'm sounding an unnecessary alarm. Just stating my observation.

Best regards,

-a-

 

 

Edited June 2, 2017 by carusoam

[bradp]

Reading the original thread, I went back to the old adage of... if there something newly wrong, so we are the doctors have been. I wonder if the voltage regulator might have been  are involved in this situation. What I am somewhat unclear about, is whether this is an overvoltage situation,  or whether it is in undervoltage/alternator field issues. One important question is whether an electrical load analysis was performed after the installation of the new electronic equipment.

[orionflt]

depending on the regulator that is installed, the over voltage light could have be reused as a alternator fail light and is just not properly labeled.

Josh, if you can download your EDM900 we can actually see what the power was doing during your flight, with this info we will know what your voltage and electrical loads were.

if the gear is putting a load on the system or generating voltage the EDM should have recorded it.

Brian 

[N601RX]

Read through your logs and see if you have the interav alternator conversion. If so these are not adjustable and my output increased in voltage as the regulator aged. It uses a separate over voltage relay. Plane power makes a replacement regulator which has the over voltage built in and is cheaper than the original regulator or over voltage relay. 

[JoshMan]

Andy, You may have been right.  Went out tonight and started the plane up.  Showed 13.8 volts and +4amps.  Do you by chance have the diagram you were talking about to reroute things?

[Andy95W]

No, but I have the email address of the current owner. I'll try to get him to take a picture of the page. 

In the meantime do you have an easy way of resetting the overvoltage relay? Usually you can pull the breaker or turn off the alternator switch. 

[Andy95W]

I contacted the owner of my former Mooney but he did not receive any manuals when he bought it (3 owners after me).  Unfortunate, because there was a good bit of institutional knowledge in those books.

The last place that Bill Wheat worked was at Dugosh in Kerrville where he was kind of an elder statesman for the Mooney Community.  I would suggest contacting them and describe some of our conversations here on MooneySpace.  They may have the information available.

Good luck, if you get a good answer please be sure to post it here.

[JoshMan]

Andy, got plane to Peoria.  They are going to add the diodes and replace the voltage regulator.  Of course I got it there and they could not reproduce the issue. I am picking up Wednesday.  Will let you know how it goes.