Mooney Low Voltage

[[email protected]]

Can anybody help me diagnose this problem? Just bought my new (to me)
1978 Mooney 201, flew it back from Kansas City to Atlanta, no problem.
Flew to Richmond, VA - again no problem. Leaving RIC for Atlanta, the
low voltage light started flashing. Didn't want to carry on IFR so
stopped into Danville. Left the plane there, and the mechanic removed
the altinator and tested it (all ok) and replaced the voltage regulator
with a new one. All ok (charging 13.9 volts). Started the plane, the
altinator gauge was showing a charge, and took off. About 30 mins into
the flight again the low voltage started flashing. By the time I had
checked all the CB's it stopped. Then about an hour later it started
again. I tried pulling the Alt Field CB and resetting, no joy. It
continued to flash untill I was in the pattern at LZU.
So, now - what next? Bad Diodes on the Altinator breaking down at
altitude?(I was at 8000'), loose altinator belt? (unlikely - it had
just been reinstalled). Over voltage on the Altinator causing the
Voltage reg to drop off line, and I didn't wait long enough when I
reset the Alt-Field circuit breaker? Bad ground straps??
Any and all thoughts welcomed at this point - this is the worst kind of
problem to hunt down.
Thanks
Ian

[Darrel Toepfer]

wrote:

> Any and all thoughts welcomed at this point - this is the worst kind of
> problem to hunt down.

How old is the battery and is it marginal? ie. can you crank and crank
or do you have to get it right the first time...

[Michelle P]

Check all of your ground connections first. Disconnect them all and
clean them.
Diodes do not break down with altitude. They are sealed. They will break
down with heat. Once they break down they are dead. The do not fail
intermittently. The brushes may be an issue though. Is the Alternator
getting enough air? Mine overheated until I installed a blast tube.
Michelle

wrote:

>Can anybody help me diagnose this problem? Just bought my new (to me)
>1978 Mooney 201, flew it back from Kansas City to Atlanta, no problem.
>Flew to Richmond, VA - again no problem. Leaving RIC for Atlanta, the
>low voltage light started flashing. Didn't want to carry on IFR so
>stopped into Danville. Left the plane there, and the mechanic removed
>the altinator and tested it (all ok) and replaced the voltage regulator
>with a new one. All ok (charging 13.9 volts). Started the plane, the
>altinator gauge was showing a charge, and took off. About 30 mins into
>the flight again the low voltage started flashing. By the time I had
>checked all the CB's it stopped. Then about an hour later it started
>again. I tried pulling the Alt Field CB and resetting, no joy. It
>continued to flash untill I was in the pattern at LZU.
>So, now - what next? Bad Diodes on the Altinator breaking down at
>altitude?(I was at 8000'), loose altinator belt? (unlikely - it had
>just been reinstalled). Over voltage on the Altinator causing the
>Voltage reg to drop off line, and I didn't wait long enough when I
>reset the Alt-Field circuit breaker? Bad ground straps??
>Any and all thoughts welcomed at this point - this is the worst kind of
>problem to hunt down.
>Thanks
>Ian
>
>
>

[[email protected]]

Battery is almost new (I believe it was replaced last year, or the year
before). It cranks just fine - I have never had any feeling that I was
running out of juice. Of course, the plane is starting first time!
According to the manual, the low volage would flash if the altinator is
not delivering a charge. That is what is leading me in that direction.

[[email protected]]

Battery is almost new (I believe it was replaced last year, or the year
before). It cranks just fine - I have never had any feeling that I was
running out of juice. Of course, the plane is starting first time!
According to the manual, the low volage would flash if the altinator is
not delivering a charge. That is what is leading me in that direction.

[[email protected]]

Thanks for that. Heat might be an issue - I had to crack the cowl flaps
open to keep the cyl head temps down yesterday - it was 10C at 8000'!
How did you install a blast tube?

[Peter R.]

> wrote:

> Any and all thoughts welcomed at this point - this is the worst kind of
> problem to hunt down.

A few months ago the low voltage light started intermittently illuminating
on my Bonanza. Since the alternator was newly rebuilt and the battery new,
we suspected that the low voltage sensor itself was having a problem.

The mechanic found that the wire leading to the low voltage sensor (don't
recall which end of the wire, however) was loose.

--
Peter
























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[[email protected]]

Thanks! That was one possibilty I had not thought of.

Ian

[Michelle P]

SInce you mentioned an alternator belt. I am assuming it is a Lycoming
with the alternator up front.
My new alternator came with the blast attachment on the back of the
unit. We ran a 1" hose to the front of the cowling. A flange may be
necessary for your installation. Mine is attached under the air filter
housing. Just under the engine air intake.

Michelle

wrote:

>Thanks for that. Heat might be an issue - I had to crack the cowl flaps
>open to keep the cyl head temps down yesterday - it was 10C at 8000'!
>How did you install a blast tube?
>
>
>

[David Lesher]

Michelle P > writes:

>Check all of your ground connections first. Disconnect them all and
>clean them.

What the woman said. Grounds are the #1 cause of intermittent problems.

Also, how do you KNOW you have a problem; besides, that is. a flakey
LV warning? Put a DVM on the bus for a flight.



--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

[Robert M. Gary]

I just spent 5 years chasing down a similar intermitant problem in my
Mooney. Turned out to be that the alternator had worn the back bearing
out of the alternator's case and was causing movement of the shaft
against the back of the case. As it torqued under load it would
sometimes lose contact.

-Robert

[Denny]

Also, how do you KNOW you have a problem; besides, that is. a flakey
LV warning? Put a DVM on the bus for a flight
************************************************** **************************

B I N G O !

Actually, one of those analog voltmeters from the auto store that you
plug into the cigarette lighter should be in everyone's airplane...
Also, does your GPS show voltage? The Garmin 295 does, and perhaps
others...

denny

[[email protected]]

Thanks for all the advise folks. If I check the voltage at the
cigarette lighter - any idea what it should be? What voltage would
cause the warning light to illuminate? (12,11, 10?).
I am going out to work on the plane tonight (first the ground straps
then go fly with a voltmeter). I'll let y'all know how it turns out...

[Denny]

With the engine at ~2000 rpm, the system voltage should be 13.6 to 14.2
volts, depending upon the state of battery charge...

denny

[[email protected]]

Thanks for the info. By the way, you said the 295 has a voltage field?
Any idea how I get it to display? (I thought only the 296 had that
field).

[Donald Royer]

I have a 1978 M20J Mooney that has been doing exactly that for 15 years.
When I first got the plane it started doing that intermitent flashing. I
changed out the voltage regulator twice and the alternator once to no avail.
I was then told by someone who should know that it was probably some kind of
a phase poblem that was not serious, and that when it happens, just check
to be sure the the alternator is charging normally and if it is don't worry
about it. He seemed to feel that it would probably go away eventually or get
bad enough that it could be tracked down. In fifteen years it has done
neither. Sometimes it will go for months without flashing, and then it will
sometimes flash for a while on almost every trip.

It has long since stopped bugging me and I now just consider it to be a
harmless quirk of my bird. Only once in the time that I have had the plane
was the warning real and it that case a check of the ampmeter immediately
indicated that the alternator was not charging. (the alternator field ground
wire had broken.) Incidently, the plane was based at LZU for about a year
when I first bought it. However, I am no longer in the Atlanta area.

Don

I don't know whether this will make you feel better or not.
> wrote in message
oups.com...
> Can anybody help me diagnose this problem? Just bought my new (to me)
> 1978 Mooney 201, flew it back from Kansas City to Atlanta, no problem.
> Flew to Richmond, VA - again no problem. Leaving RIC for Atlanta, the
> low voltage light started flashing. Didn't want to carry on IFR so
> stopped into Danville. Left the plane there, and the mechanic removed
> the altinator and tested it (all ok) and replaced the voltage regulator
> with a new one. All ok (charging 13.9 volts). Started the plane, the
> altinator gauge was showing a charge, and took off. About 30 mins into
> the flight again the low voltage started flashing. By the time I had
> checked all the CB's it stopped. Then about an hour later it started
> again. I tried pulling the Alt Field CB and resetting, no joy. It
> continued to flash untill I was in the pattern at LZU.
> So, now - what next? Bad Diodes on the Altinator breaking down at
> altitude?(I was at 8000'), loose altinator belt? (unlikely - it had
> just been reinstalled). Over voltage on the Altinator causing the
> Voltage reg to drop off line, and I didn't wait long enough when I
> reset the Alt-Field circuit breaker? Bad ground straps??
> Any and all thoughts welcomed at this point - this is the worst kind of
> problem to hunt down.
> Thanks
> Ian
>

[Robert M. Gary]

Donald Royer wrote:

> It has long since stopped bugging me and I now just consider it to be a
> harmless quirk of my bird. Only once in the time that I have had the plane
> was the warning real and it that case a check of the ampmeter immediately
> indicated that the alternator was not charging. (the alternator field ground
> wire had broken.) Incidently, the plane was based at LZU for about a year
> when I first bought it. However, I am no longer in the Atlanta area.

You can never have too many field grounds. I have 3 on my Mooney. They
don't cost much and its an easy back up to make. People spend thousands
on back up vac systems but sometimes miss the opportunity to spend 5
minutes putting an extra ground wire from the alternator to the frame.

-Robert

[Denny]

Umm, doh , you are right, it is the 296 not the 295... Good thing I
have sharp eyes on the list to keep me honest... Too many GPS to keep
track of... Currently I have a 395 and a 296 mounted in the Apache...
Recently sold a 295 and a 100 (do I like Garmin GPS or what?)... My
first one was the ProNav 100, the factory's, one and only, demonstrator
which I pried out of the hands of their CEO on the closing day of the
show at 4PM - I ran out of the commercial building, stuffed it into my
Super Viking and used it to navigate back to Michigan... From that
flight on, I was sold on the benefits of GPS... Garmin later bought
them out to get into the GPS business and named it the Garmin GPS
100...

denny

[Jon Woellhaf]

"Denny" wrote, "... Currently I have a 395 and a 296 mounted in the
Apache..."

What is a 395?

[Ian Taylor]

Thanks, I think, Don!
I don't like the idea of an intermittant flashing warning light. But for
now, I have put an in-line digital volt meter in the cigarette lighter, and
will be able to keep an eye on the voltage.
I am probably going to replace the battery and alternator, just to be safe,
and of course recheck all the grounds, and perhaps try to check the wiring
to the warning panel. But if that doesn't stop it, then, I hope I get to the
point that it doesn't bother me!

Thanks to everyone for the input!
Ian

"Donald Royer" > wrote in message
link.net...
> I have a 1978 M20J Mooney that has been doing exactly that for 15 years.
> When I first got the plane it started doing that intermitent flashing. I
> changed out the voltage regulator twice and the alternator once to no
avail.
> I was then told by someone who should know that it was probably some kind
of
> a phase poblem that was not serious, and that when it happens, just check
> to be sure the the alternator is charging normally and if it is don't
worry
> about it. He seemed to feel that it would probably go away eventually or
get
> bad enough that it could be tracked down. In fifteen years it has done
> neither. Sometimes it will go for months without flashing, and then it
will
> sometimes flash for a while on almost every trip.
>
> It has long since stopped bugging me and I now just consider it to be a
> harmless quirk of my bird. Only once in the time that I have had the plane
> was the warning real and it that case a check of the ampmeter immediately
> indicated that the alternator was not charging. (the alternator field
ground
> wire had broken.) Incidently, the plane was based at LZU for about a year
> when I first bought it. However, I am no longer in the Atlanta area.
>
> Don
>
> I don't know whether this will make you feel better or not.
> > wrote in message
> oups.com...
> > Can anybody help me diagnose this problem? Just bought my new (to me)
> > 1978 Mooney 201, flew it back from Kansas City to Atlanta, no problem.
> > Flew to Richmond, VA - again no problem. Leaving RIC for Atlanta, the
> > low voltage light started flashing. Didn't want to carry on IFR so
> > stopped into Danville. Left the plane there, and the mechanic removed
> > the altinator and tested it (all ok) and replaced the voltage regulator
> > with a new one. All ok (charging 13.9 volts). Started the plane, the
> > altinator gauge was showing a charge, and took off. About 30 mins into
> > the flight again the low voltage started flashing. By the time I had
> > checked all the CB's it stopped. Then about an hour later it started
> > again. I tried pulling the Alt Field CB and resetting, no joy. It
> > continued to flash untill I was in the pattern at LZU.
> > So, now - what next? Bad Diodes on the Altinator breaking down at
> > altitude?(I was at 8000'), loose altinator belt? (unlikely - it had
> > just been reinstalled). Over voltage on the Altinator causing the
> > Voltage reg to drop off line, and I didn't wait long enough when I
> > reset the Alt-Field circuit breaker? Bad ground straps??
> > Any and all thoughts welcomed at this point - this is the worst kind of
> > problem to hunt down.
> > Thanks
> > Ian
> >
>
>

[Aaron Coolidge]

Denny > wrote:
: Also, does your GPS show voltage? The Garmin 295 does, and perhaps
: others...

: denny

Denny, where is this feature? I've had my 295 for 4 years and have never
seen this.. I do know the 195 shows voltage, perhaps this is what you mean?
--
Aaron C.

[Denny]

That's tangled fingers when I had to leave in a hurry/// Try 296 and
196...

[Denny]

195 not 295... Sorry for the typos..