Mooney M20E io360 low voltage problem

Hello, I own a 65 m20e with a io360. Recently been experiencing noise on com1 and have read about low voltage being a problem with nav/com's. I have a king ki 165 for both com1 and com2. I've tried to diagnose the problem and it appers that my alternator isn't charging the batter correctly nor is it bringing the system bus up to 14volts. I've noticed this via a volt meter to the 12 volt(car type) adatper(although i don't know if this is the correct procedure) and I've also made notes of the bus voltage before starting and after shutdown on a long flight and it went from 13.5 volts to 12.2 volts(enging off). Does this seem like it could be a low voltage noise from a alternator not charging correctly. If so has anyone had experience repairing alternators on m20e. I would imagine a new one would cost around 1K. But I don't know.

Thanks

Mike

Mike Harvey writes:


Hello, I own a 65 m20e with a io360. Recently been experiencing noise
on com1 and have read about low voltage being a problem with nav/com's.
I have a king ki 165 for both com1 and com2. I've tried to diagnose the
problem and it appers that my alternator isn't charging the batter
correctly nor is it bringing the system bus up to 14volts. I've
noticed this via a volt meter to the 12 volt(car type) adatper(although
i don't know if this is the correct procedure) and I've also made notes
of the bus voltage before starting and after shutdown on a long flight
and it went from 13.5 volts to 12.2 volts(enging off). Does this seem
like it could be a low voltage noise from a alternator not charging
correctly. If so has anyone had experience repairing alternators on
m20e. I would imagine a new one would cost around 1K. But I don't
know.

First, clean and tighten all the connections, most especially the
battery ground, engine to frame strap and regulator grounding.


--
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

On Mon, 16 Feb 2009 21:41:07 +0000, Mike Harvey
wrote:


Hello, I own a 65 m20e with a io360. Recently been experiencing noise
on com1 and have read about low voltage being a problem with nav/com's.
I have a king ki 165 for both com1 and com2. I've tried to diagnose the
problem and it appers that my alternator isn't charging the batter
correctly nor is it bringing the system bus up to 14volts. I've
noticed this via a volt meter to the 12 volt(car type) adatper(although
i don't know if this is the correct procedure) and I've also made notes
of the bus voltage before starting and after shutdown on a long flight
and it went from 13.5 volts to 12.2 volts(enging off). Does this seem
like it could be a low voltage noise from a alternator not charging
correctly. If so has anyone had experience repairing alternators on
m20e. I would imagine a new one would cost around 1K. But I don't
know.

Thanks

Mike

A fully charged 12V battery should read 12.7V with everything turned off
for a few hours. So either there is a significant voltage drop to your
cigar lighter, or your voltmeter is not accurate.

You could have loose or corroded connections anywhere in the circuit.

What kind of alternator? -- the original had a generator, but there have
been STC's for various alternator mods.

I've not had noise as a radio problem (in my 65 M20E) with 13+ volts on the
bus (KX155 radio). With low voltage (under 11-12 or so, can't recall
exactly), the first thing that seems to go is the squelch.
--ron

Originally Posted by Ron Rosenfeld

On Mon, 16 Feb 2009 21:41:07 +0000, Mike Harvey
wrote:
[color=blue][i]


A fully charged 12V battery should read 12.7V with everything turned off
for a few hours. So either there is a significant voltage drop to your
cigar lighter, or your voltmeter is not accurate.

You could have loose or corroded connections anywhere in the circuit.

What kind of alternator? -- the original had a generator, but there have
been STC's for various alternator mods.

I've not had noise as a radio problem (in my 65 M20E) with 13+ volts on the
bus (KX155 radio). With low voltage (under 11-12 or so, can't recall
exactly), the first thing that seems to go is the squelch.
--ron

Thanks for the response. It could be a bad connection to the ground. As previous stated and to further clarify, I usually keep a trickle charger on the battery and when I first go flying the battery before starting is 13.5 volts. and no noise on the radio. When I get back the voltage is 12.5 or less and I get noise on the radio. I've had a tech check out the antennas and no problems and com1 was recently overhalled last year. Com2 does not experience any problems. I don't have a generator but I don't know what type of alternator it is. Need to look at the log books

Mike

Mike Harvey writes:



Thanks for the response. It could be a bad connection to the ground.
As previous stated and to further clarify, I usually keep a trickle
charger on the battery and when I first go flying the battery before
starting is 13.5 volts. and no noise on the radio. When I get back
the voltage is 12.5 or less and I get noise on the radio. I've had a
tech check out the antennas and no problems and com1 was recently
overhalled last year. Com2 does not experience any problems. I don't
have a generator but I don't know what type of alternator it is. Need
to look at the log books


First, buy a voltmeter. You can buy a quite usable DVM from Harbor
Freight for $3-$5, depending on sales. I own about 4; one in the car,
one in the toolbag, etc.

Then use it to measure the battery voltage ON the battery terminals.
With the master off, etc. it should be at least 13.5 volts.

Can you safely start the plane and still get to the battery?

With the aircraft at least running; it should be above that. With it run
up a little, it should hit 14.4.

Then add loads; lights and pitot heat come to mind. You should still
be holding at 14 volts.

If not, something is wrong in your charging circuit. What do the panel
instruments say?
--
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

On Wed, 18 Feb 2009 00:42:34 +0000 (UTC), David Lesher
wrote:

Then use it to measure the battery voltage ON the battery terminals.
With the master off, etc. it should be at least 13.5 volts.

Unlikely to reach 13.5 volts unless the engine is running, or the battery
is connected to a charger. (Or it is very cold).

For a lead-acid battery, fully charged at 78°F, voltage should read about
2.12VPC (volts per cell) * 6 cells = 12.72V.

An AGM style battery might be slightly higher, but I don't think it's
higher than 12.8V.
--ron

On Tue, 17 Feb 2009 15:03:41 +0000, Mike Harvey
wrote:

Thanks for the response. It could be a bad connection to the ground.
As previous stated and to further clarify, I usually keep a trickle
charger on the battery and when I first go flying the battery before
starting is 13.5 volts. and no noise on the radio. When I get back
the voltage is 12.5 or less and I get noise on the radio. I've had a
tech check out the antennas and no problems and com1 was recently
overhalled last year. Com2 does not experience any problems. I don't
have a generator but I don't know what type of alternator it is. Need
to look at the log books

Mike

The 13.5V initially, if accurate, is probably a consequence of having had
the battery on the charger. It should read 12.7V fully charged but that
also means with no loads or charging after about three hours. If it is
reading 13.5 and has been off the charger for a while, then your voltmeter
may be reading high. That being the case, your 12.5V may really be 11.7V
or lower which might be low enough to cause your problem.
--ron

Depending on the electrical load you are running you likely won't get
14 when running. Especially if you turn on the landing light, pitot
heat etc. A new alternator is really not that expensive but you can
test some other things first. As others have mentioned, you want to
check the grounds. Is the voltage consistant in flight or does it
bounce around? Anyone with a fuel injected engine should put buying
something like an EDM high on their priority list. As a side benefit,
such a device will show you voltage at all times so you can track it
durin the flight if its not holding steady.

-Robert


On Feb 16, 1:41*pm, Mike Harvey Mike.Harvey.
wrote:
Hello, *I own a 65 m20e with a io360. *Recently been experiencing noise
on com1 and have read about low voltage being a problem with nav/com's.
I have a king ki 165 for both com1 and com2. *I've tried to diagnose the
problem and it appers that my alternator isn't charging the batter
correctly nor is it bringing the system bus up to 14volts. *I've
noticed this via a volt meter to the 12 volt(car type) adatper(although
i don't know if this is the correct procedure) and I've also made notes
of the bus voltage before starting and after shutdown on a long flight
and it went from 13.5 volts to 12.2 volts(enging off). *Does this seem
like it could be a low voltage noise from a alternator not charging
correctly. *If so has anyone had experience repairing alternators on
m20e. *I would imagine a new one would cost around 1K. *But I don't
know.

Thanks

Mike

--
Mike Harvey

"Robert M. Gary" wrote

Anyone with a fuel injected engine should put buying
something like an EDM high on their priority list. As a side benefit,
such a device will show you voltage at all times so you can track it
durin the flight if its not holding steady.

EDM? I know I will be smacking my forehead when someone tells me what it
is. g
--
Jim in NC

On Feb 18, 6:55*pm, "Morgans" wrote:
"Robert M. Gary" wrote

*Anyone with a fuel injected engine should put buying
something like an EDM high on their priority list. As a side benefit,
such a device will show you voltage at all times so you can track it
durin the flight if its not holding steady.

EDM? *I know I will be smacking my forehead when someone tells me what it
is. *g
--
Jim in NC

Its the engine monitor product made by JPI. GEM makes one as well.
There are some additional companies that make simple gauges to just
show the temps but those are the only two that make full engine
monitors.

-Robert