Today's Message Index:
----------------------
1. 06:17 AM - Re: B&C alternator diagnosis (Robert L. Nuckolls, III)
2. 06:19 AM - Re: vhf transponder interference (Robert L. Nuckolls, III)
3. 07:07 AM - Re: radio interference? (Robert L. Nuckolls, III)
4. 07:07 AM - Re: Re: turn coordinator causing noise in headset (Robert L. Nuckolls, III)
5. 07:21 AM - Re: Re: turn coordinator causing noise in headset (Robert L. Nuckolls, III)
6. 08:09 AM - Re: radio interference? (thomas sargent)
7. 10:20 AM - Open Source Avionics (gregmchugh)
8. 10:23 AM - Re: B&C alternator diagnosis (Henry Hallam)
9. 10:39 AM - Preventing RF Noise Pollution (Jeff Luckey)
10. 10:59 AM - Re: Open Source Avionics (Henry Hallam)
11. 02:30 PM - Re: B&C alternator diagnosis (Robert L. Nuckolls, III)
12. 02:37 PM - Re: Preventing RF Noise Pollution (Robert L. Nuckolls, III)
13. 04:35 PM - Re: Open Source Avionics (Vern Little)
14. 05:17 PM - Re: B&C alternator diagnosis (DVS)
15. 07:46 PM - Odyssey Battery Longevity (DEAN PSIROPOULOS)
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Subject: | Re: B&C alternator diagnosis |
>I will definitely be fitting a reliable voltmeter and warning light.
>Unfortunately I don't have a wiring diagram, though I'm working on
>putting one together from my own notes taken during maintenance and
>upgrades. My rectifier/regulator is mounted on the engine side of the
>firewall, in what I think is a relatively cool location (on the high
>pressure side of the updraft cooling system).
Good
>The positive output
>goes via a 14 AWG wire to a 10-amp CB on the instrument panel and from
>there to the positive battery terminal (battery in the nose of the
>canard-pusher airplane).
Does your airplane have a starter? If so, where
is the starter contactor located?
>The negative output goes to a general ground
>terminal on the engine mount frame and from there via a similar 14 AWG
>wire to the negative battery terminal.
Hmmmm . . . I deduce that there is no starter
and the 14AWG ground is the only conductor between
the crankcase and the battery(-)?
> The instrument power bus is
>connected to the battery terminals by another set of wires, and
>there's a third set for the electronic ignition.
Hmmmm . . . battery terminal used as a power distribution
point. Is there a battery switch?
>Any reason not to tune the regulator voltage setpoint on the bench
>with a constant-current bench supply on the blue wires and my airplane
>battery on the red+black?
Yes, this is a crude form of switchmode regulator.
Not of the inductor-stored energy variety, but a
duty cycle switched series regulator with SCR's
that get triggered in a variable position along
each half-cycle of the incoming waveform.
It must be adjusted under operating conditions that
mimic the as-installed condition on the airplane.
Here's a schematic of an exemplar rectifier/regulator
for a PM alternator:
http://tinyurl.com/94585zs
When we crafted installation instructions for that
regulator/alternator combination on a no-starter
airplane years ago, I brought ac power to the
battery area on a twisted pair. The R-R was mounted
close to the battery so that series resistance in the
sense-lines shared with power-delivery lines did
not become significant impedances in the control
loop.
Later drawings published by B&C dropped that
configuration. That's been so long ago that I
don't recall if I had any conversation with them
about the change. I cannot prove that the old
configuration was demonstrably 'better' but it
was crafted with consideration for deleterious
effects of unnecessary resistance in sense
feeders shared with power feeders.
Don't know if it's an option for you but you
might consider using the 14AWG pair coming
forward as AC power feeders and move the R-R
to the forward space shared with the battery.
Bob . . .
Message 2
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Subject: | Re: vhf transponder interference |
At 04:40 PM 10/29/2012, you wrote:
>
>Hello everyone
>
>I'm a new member here and looking for some help on a problem I've
>noticed approx. 2 years ago.
>
>1- When I transmit on my Garmin GNC 250XL, some gauges on my panel
>go haywire. ie: Mitchell fuel level indicator.
>
>2- When I trasnmit, ATC tells me my altitude changes on his radar (
>transponder Garmin GTX-320) encoder AK-350.
>
>3- When I put my X-Ponder from Off to any position ( SBY, ON, ALT )
>a "White" noise can be heard in my headset ( only while receiving).
>
>4-Receiving deteriorate as the flight goes.
>
>airplane all fiberglass, C-GGYY to see pictures
Your cockpit is "hot" with RF energy generated
by the transmitter. The most prevalent cause of
this condition is a poorly installed coax connector
at either end of the comm antenna feeder but
especially the transceiver end.
Check this connector to make sure the shield
ground integrity is good.
Bob . . .
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Subject: | Re: radio interference? |
At 03:10 PM 10/29/2012, you wrote:
At Ryan field yesterday a fellow I know who has
done an incredible job building a perfect Hatz
bi-plane asked me for help with a very odd radio
problem. He has about 10 flights on it so far.
His brand new ICOM radio produces only very soft,
badly garbled reception when his engine (Lyc.
O-290) is running. He can't talk to the tower
when he's on-airport without stopping the
engine. The really odd part is that the same is
true if he uses a hand-held radio. (The ICOM
has been benched checked by an official shop and looks fine.)
His belly mounted antenna was obviously poor
since it had a 90 deg. bend it it about 2 inches
after it emerges from the plane. It has what
looks like a good ground plane. He's switching
to a plain, straight whip antenna for next
flight. But I doubt it will work any better
given the performance of the hand-held.
I agree. Pretzel shaped antennas may not perform
as well as the idealized configurations . . . but
gross performance is not likely to be the root
cause of a noise/interference issue in the radio.
Is the hand-held on a rubber-duck when these
experiments are tried or is it plugged into
ship's antenna?
He was also going to fly it once with the
magnetos shorted at the magneto (so the wires
going from the mag to the switch will be
disconnected, thinking they may be radiating somehow).
Good experiment . . . but the flavor of noise
emitted by magneto p-lead circuits is of the
short duration, repetitive 'spark plug' variety.
The phenomenon you describe sounds more like the
effects of a smoother, more contiguous stress.
Noise? Are these radios being tested with a common
mic/head-set? If so, try another mic/head-set.
Bob . . .
Message 4
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Subject: | Re: turn coordinator causing noise in headset |
At 02:31 PM 10/29/2012, you wrote:
>
>As I mentioned earlier, I have had my fair share of electrical
>issues. It appears that this noise is the result of or partially
>caused by low voltage directly related to another electrical problem.
>
>The original builder wired in a hotbox. In the hotbox instructions
>it says to run the two AC lines from the alternator to the hotbox.
>Apparently some of the Hotboxes had the regulator attached to them
>and jumpers are need to connect to the regulator. In my case, the
>regulator is on the firewall. The original builder split the the two
>AC lines with a crimp connector. He had two AC lines going to the
>hotbox which were not needed and then had two going to the the
>regulator with the 12 volt DC line output going to the charging
>circuit. I discovered that these crimp connectors had bad
>connections causing resistance and ultimately melted the AC wires
>together essentially shorting out the AC current. That caused the
>battery to not charge and caused low voltage. I eliminated the split
>and ran the AC lines directly to the regulator, crimped and soldered
>all the connections and the alternator is now charging the battery.
>I charged the battery with a good battery charger and flew
>yesterday. It appears that the noise is either gone or lessened to
>the point that I cannot hear over the engine. So I guess that low
>voltage was the main culprit with the melted wires causing the low
>voltage situation by not charging the battery. Thanks for all the
>thoughts and advice on this.
>
>
>Read this topic online here:
>
>http://forums.matronics.com/viewtopic.php?p=386225#386225
>
>
>-----
>No virus found in this message.
>Checked by AVG - www.avg.com
Bob . . .
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Subject: | Re: turn coordinator causing noise in headset |
At 02:31 PM 10/29/2012, you wrote:
As I mentioned earlier, I have had my fair share of electrical
issues. It appears that this noise is the result of or partially
caused by low voltage directly related to another electrical problem.
The original builder wired in a hotbox. In the hotbox instructions it
says to run the two AC lines from the alternator to the hotbox.
Apparently some of the Hotboxes had the regulator attached to them
and jumpers are need to connect to the regulator. In my case, the
regulator is on the firewall. The original builder split the the two
AC lines with a crimp connector. He had two AC lines going to the
hotbox which were not needed and then had two going to the the
regulator with the 12 volt DC line output going to the charging
circuit. I discovered that these crimp connectors had bad connections
causing resistance and ultimately melted the AC wires together
essentially shorting out the AC current. That caused the battery to
not charge and caused low voltage. I eliminated the split and ran the
AC lines directly to the regulator, crimped and soldered all the
connections and the alternator is now charging the battery. I charged
the battery with a good battery charger and flew yesterday. It
appears that the noise is either gone or lessened to the point that I
cannot hear over the engine. So I guess that low voltage was the main
culprit with the melted wires causing the low voltage situation by
not charging the battery. Thanks for all the thoughts and advice on this.
An interesting narrative! My writings and the
seminars try to emphasize that a part NOT installed
on the airplane is incapable of being a performance/
maintenance issue later. Keeping the parts count down
not only reduces the cost of acquisition and installation,
it reduces the future costs of ownership too.
Pre-assembled products like the hot-box, exp-bus,
and even Greg Richter's "solid-state breaker
board" may blow warm fuzzy siren songs in the
builder's ear . . . while in fact the builder
is trading in his own understanding and system
reliability for the convenience of somebody else's
plug-n-play understanding.
After more than 30 years observation and participation
in this industry, I have yet to see an off-the-shelf
assembly of electro-whizzies that competes in $value$
for a handful of breakers/fuses, switches and a couple
of contactors. Sometimes the best way to drive a nail
is with a hammer.
Bob . . .
Message 6
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Subject: | Re: radio interference? |
Bob:
I'll have to check for sure, but I think the hand held was on its own
antenna and not connected into the plane's antenna. Switching headsets is
a good suggestion. I'll tell him about that.
I agree that his description of the noise doesn't sound like ignition
noise. It's like another radio is is squashing the signal somehow. I
can't figure how the ICOM could do that to itself and still check out on
the bench, though. Weird.
Thanks for the suggestions.
--
Tom Sargent
Message 7
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Subject: | Open Source Avionics |
Open Source Avionics, something we have discussed on the list is also happening
over at MakerPlane as part of their open source aircraft work...
http://makerplane.org/?p=1050
Greg McHugh
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=386301#386301
Message 8
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Subject: | Re: B&C alternator diagnosis |
On Tue, Oct 30, 2012 at 6:11 AM, Robert L. Nuckolls, III
<nuckolls.bob@aeroelectric.com> wrote:
>> The positive output
>> goes via a 14 AWG wire to a 10-amp CB on the instrument panel and from
>> there to the positive battery terminal (battery in the nose of the
>> canard-pusher airplane).
>
> Does your airplane have a starter? If so, where
> is the starter contactor located?
>
No starter.
>
>> The negative output goes to a general ground
>> terminal on the engine mount frame and from there via a similar 14 AWG
>> wire to the negative battery terminal.
>
>
> Hmmmm . . . I deduce that there is no starter
> and the 14AWG ground is the only conductor between
> the crankcase and the battery(-)?
Yes, except there are probably some other (skinnier) ground paths due
to engine sensors and the electronic ignition. The main ground
conductor might be 12 AWG rather than 14, I'll check tomorrow.
>> The instrument power bus is
>> connected to the battery terminals by another set of wires, and
>> there's a third set for the electronic ignition.
>
>
> Hmmmm . . . battery terminal used as a power distribution
> point. Is there a battery switch?
There's a switch labeled "battery" that supplies the instrument bus
(with individual CBs after that for each instrument). Is this
arrangement a bad idea?
>
>> Any reason not to tune the regulator voltage setpoint on the bench
>> with a constant-current bench supply on the blue wires and my airplane
>> battery on the red+black?
>
>
> Yes, this is a crude form of switchmode regulator.
> Not of the inductor-stored energy variety, but a
> duty cycle switched series regulator with SCR's
> that get triggered in a variable position along
> each half-cycle of the incoming waveform.
>
> It must be adjusted under operating conditions that
> mimic the as-installed condition on the airplane.
> Here's a schematic of an exemplar rectifier/regulator
> for a PM alternator:
>
> http://tinyurl.com/94585zs
Makes sense, thanks!
>
> When we crafted installation instructions for that
> regulator/alternator combination on a no-starter
> airplane years ago, I brought ac power to the
> battery area on a twisted pair. The R-R was mounted
> close to the battery so that series resistance in the
> sense-lines shared with power-delivery lines did
> not become significant impedances in the control
> loop.
Interesting. It's great to get insight from the designer.
>
> Later drawings published by B&C dropped that
> configuration. That's been so long ago that I
> don't recall if I had any conversation with them
> about the change. I cannot prove that the old
> configuration was demonstrably 'better' but it
> was crafted with consideration for deleterious
> effects of unnecessary resistance in sense
> feeders shared with power feeders.
>
> Don't know if it's an option for you but you
> might consider using the 14AWG pair coming
> forward as AC power feeders and move the R-R
> to the forward space shared with the battery.
>
I'll look into it - I agree that sounds like a better arrangement
feedback-wise, but I don't think the existing wire run I have is a
twisted pair, so I'd be a bit concerned about EMI emissions from that
long of a run of chopped AC. I'll see how much trouble a new wire run
would be. If I had the time it could be a fun project to design my
own switching regulator with separate sense lines... for that matter,
do you know why these brushless alternator designs didn't use three
phases like a modern BLDC motor?
Thanks again
Henry
Message 9
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Subject: | Preventing RF Noise Pollution |
All,
I want to put a device which contains a micro-controller clocked @ 1 MHz in
my RV-7. I want it to be a good electronic citizen in the electromagnetic
village of my electrical system. (I don't want it to annoy its neighbors)
I'm looking for guidelines on how to prevent the device from introducing
noise back thru its power feed line. Can I put a filter on the circuit
board on the incoming power line? There is a 5v regulator - are those
devices noisy?
In an effort to reduce radiated noise, it is enclosed in an aluminum box
that seals well.
There is also control wiring that must travel thru the airframe. Should
those wires have some kind of filtering on them as well? Some of the
external wires are sensing remote analog voltages. Do they need protection
also?
TIA,
Jeff Luckey
Message 10
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Subject: | Re: Open Source Avionics |
Nice! The way they fit most of the projects in D-sub housings is a neat idea.
If anyone is interested in a DIY 2-place intercom, I posted my CAD
files here: https://github.com/henryhallam/intercom
It's based closely on a design released by Dave Allen in 1997, but
uses surface-mount parts (still easily hand-solderable) and includes
USB power outlets. I plan to add a bluetooth interface for a cell
phone or music and I'll update the git when I do that.
Henry
On Tue, Oct 30, 2012 at 10:17 AM, gregmchugh <gregmchugh@aol.com> wrote:
>
> Open Source Avionics, something we have discussed on the list is also happening
over at MakerPlane as part of their open source aircraft work...
>
> http://makerplane.org/?p=1050
>
> Greg McHugh
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=386301#386301
>
>
Message 11
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Subject: | Re: B&C alternator diagnosis |
>
>I'll look into it - I agree that sounds like a better arrangement
>feedback-wise, but I don't think the existing wire run I have is a
>twisted pair, so I'd be a bit concerned about EMI emissions from that
>long of a run of chopped AC.
I've not had an opportunity to run a PM alternator in
the lab . . . so the twisted pair was simple a prophylactic
derived from common sense. In any case, I doubt that
EMI products go very high in frequency. Given that ADF
is gone (taking am radio with it), the probability
for real interference is small. It would be a relatively
easy experiment. See if you can use the existing 14AWG
pair as an AC power feeder and then fly it.
> I'll see how much trouble a new wire run would be.
Many moons ago, I was able to use an existing wire as
a pull-tape to run in a new instrumentation wire . . .
a shielded trio. The bundles between firewall and the nose
section were not tightly tied.
You might see if tugging on the 14AWG produces any
significant motion at non-scary forces.
> If I had the time it could be a fun project to design my
>own switching regulator with separate sense lines...
Yeah, I have such a design somewhere. I'll see if I
can dig it out. The design is a buck-regulator scaled
to run off the un-regulated, full wave rectified DC
out of the alternator. I looked at that product about
20 years ago but some new kids on the block might
re-open the door. Consider this:
A full wave rectifier on the firewall and local
capacitor would get you unregulated, HV dc. I don't
recall now what the open circuit AC votlage is for
your alternator at cruise . . . you might get a measurement
at some known ramp RPM from which we can extrapolate
the higher rpm value. Use a rectifier and filter capacitor
with a light load, say 100 ohms across it. Measure the resulting
DC at some handy RPM.
If max DC is below 28, then this regulator might have
promise:
http://tinyurl.com/8fm6reh
Given that you do not have a starter, there may not
be a good reason to keep a battery on board . . .
or the battery could be scaled down to deal with
only with taxi rpm situations. These regulators provide
constant, clean output as long as the input is
high enough. You might even consider two regulators.
They're light and smaller than a battery. One could
be a standby. It's exceedingly unlikely that you would
ever loose the alternator.
Food for thought.
for that matter,
>do you know why these brushless alternator designs didn't use three
>phases like a modern BLDC motor?
You could do that . . . here's an interesting
motor
Emacs!
Emacs!
BEMF of 6v/krpm says you'll get about 24 volts at
4000 pad drive speeds. The winding resistances are
low. It seems that you would get 10A plus out of this
motor back-driven as a PM, 3-phase alternator.
It would cost you about $200 to put your hands on one
to play with.
http://tinyurl.com/95jny8c
Bob . . .
Message 12
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Subject: | Re: Preventing RF Noise Pollution |
At 01:36 PM 10/30/2012, you wrote:
All,
I want to put a device which contains a micro-controller clocked @ 1 MHz in
my RV-7. I want it to be a good electronic citizen in the electromagnetic
village of my electrical system. (I don't want it to annoy its neighbors)
I'm looking for guidelines on how to prevent the device from introducing
noise back thru its power feed line. Can I put a filter on the circuit
board on the incoming power line? There is a 5v regulator - are those
devices noisy?
In an effort to reduce radiated noise, it is enclosed in an aluminum box
that seals well.
#1 rule, make the board layout tight. Make use of a
ground plane if you can. Self contained uC devices
have VERY tiny radiation apertures and few external
leads (oscillator) that carry fast rise, potentially
antagonistic signals.
There is also control wiring that must travel thru the airframe. Should
those wires have some kind of filtering on them as well? Some of the
external wires are sensing remote analog voltages. Do they need protection
also?
Generally not for RF. Your control and analog lines will
generally benefit from some form of level shifting and/or
filtering for input transient immunity . . . this same
network wipes out the RF issues too.
Power inputs for small circuits are also benign. You'll
no doubt be using a linear regulator which, along with
it's standard line capacitors, is a strong attenuator
of RF.
Small devices like this are seldom an radiated
or conducted EMI concern. Your biggest integration
concerns are for protecing the uC from outside
stresses (Mil-Std-704 DC power and static discharges
for handling).
Send me a copy of your schematic and I'll suggest
i/o conditioning networks.
Bob . . .
Message 13
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Subject: | Re: Open Source Avionics |
Henry, if you are interested in posting the intercom into the public domain,
MakerPlane is the place to do it. We'd like it if you could submit the info.
If you want, I can prepare the files for you and then send them to John
Nicol at MakerPlane.
Thanks, Vern Little
Vx Aviation
-----Original Message-----
From: Henry Hallam
Sent: Tuesday, October 30, 2012 10:56 AM
Subject: Re: AeroElectric-List: Open Source Avionics
<henry@pericynthion.org>
Nice! The way they fit most of the projects in D-sub housings is a neat
idea.
If anyone is interested in a DIY 2-place intercom, I posted my CAD
files here: https://github.com/henryhallam/intercom
It's based closely on a design released by Dave Allen in 1997, but
uses surface-mount parts (still easily hand-solderable) and includes
USB power outlets. I plan to add a bluetooth interface for a cell
phone or music and I'll update the git when I do that.
Henry
On Tue, Oct 30, 2012 at 10:17 AM, gregmchugh <gregmchugh@aol.com> wrote:
>
> Open Source Avionics, something we have discussed on the list is also
> happening over at MakerPlane as part of their open source aircraft work...
>
> http://makerplane.org/?p=1050
>
> Greg McHugh
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=386301#386301
>
>
-----
No virus found in this message.
Checked by AVG - www.avg.com
Message 14
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Subject: | B&C alternator diagnosis |
Bob,
This is fairly common in the RC industry. See
http://mysite.verizon.net/vze49gsg Raja may be interested in building the
rectifiers.
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Tuesday, October 30, 2012 2:27 PM
Subject: Re: AeroElectric-List: B&C alternator diagnosis
I'll look into it - I agree that sounds like a better arrangement
feedback-wise, but I don't think the existing wire run I have is a
twisted pair, so I'd be a bit concerned about EMI emissions from that
long of a run of chopped AC.
I've not had an opportunity to run a PM alternator in
the lab . . . so the twisted pair was simple a prophylactic
derived from common sense. In any case, I doubt that
EMI products go very high in frequency. Given that ADF
is gone (taking am radio with it), the probability
for real interference is small. It would be a relatively
easy experiment. See if you can use the existing 14AWG
pair as an AC power feeder and then fly it.
I'll see how much trouble a new wire run would be.
Many moons ago, I was able to use an existing wire as
a pull-tape to run in a new instrumentation wire . . .
a shielded trio. The bundles between firewall and the nose
section were not tightly tied.
You might see if tugging on the 14AWG produces any
significant motion at non-scary forces.
If I had the time it could be a fun project to design my
own switching regulator with separate sense lines...
Yeah, I have such a design somewhere. I'll see if I
can dig it out. The design is a buck-regulator scaled
to run off the un-regulated, full wave rectified DC
out of the alternator. I looked at that product about
20 years ago but some new kids on the block might
re-open the door. Consider this:
A full wave rectifier on the firewall and local
capacitor would get you unregulated, HV dc. I don't
recall now what the open circuit AC votlage is for
your alternator at cruise . . . you might get a measurement
at some known ramp RPM from which we can extrapolate
the higher rpm value. Use a rectifier and filter capacitor
with a light load, say 100 ohms across it. Measure the resulting
DC at some handy RPM.
If max DC is below 28, then this regulator might have
promise:
http://tinyurl.com/8fm6reh
Given that you do not have a starter, there may not
be a good reason to keep a battery on board . . .
or the battery could be scaled down to deal with
only with taxi rpm situations. These regulators provide
constant, clean output as long as the input is
high enough. You might even consider two regulators.
They're light and smaller than a battery. One could
be a standby. It's exceedingly unlikely that you would
ever loose the alternator.
Food for thought.
for that matter,
do you know why these brushless alternator designs didn't use three
phases like a modern BLDC motor?
You could do that . . . here's an interesting
motor
Emacs!
Emacs!
BEMF of 6v/krpm says you'll get about 24 volts at
4000 pad drive speeds. The winding resistances are
low. It seems that you would get 10A plus out of this
motor back-driven as a PM, 3-phase alternator.
It would cost you about $200 to put your hands on one
to play with.
http://tinyurl.com/95jny8c
Bob . . .
Message 15
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Subject: | Odyssey Battery Longevity |
Just finished my fourth annual on the RV-6A. When I built the airplane I
installed the firewall mounted battery kit with the Odyssey PC680 battery.
Being an aficionado of Bob's philosophy I was originally going to replace
the battery after two years of service. I had however, heard many great
things about the Odyssey and decided to keep it in service after my second
annual, it was working perfectly and I could find no reason to spend another
$150 for a new one. Same great service in 2011 so I decided I'd let it run
for one more year. This year I decided I'd replace it regardless of how it
was performing so, I bought a new one and installed it (even though the 4
year old one still cranked the airplane vigorously). I was curious how much
capacity remained in the old battery so I took it to an auto parts store and
had them load test it. Results...4 year old Odyssey still put out 207 of
its 220 CCA rated capacity. That's an incredible 94% capacity remaining
after FOUR years!!! Down here in Florida we are lucky to get 4 years of
service out of a flooded cell car battery and the Odyssey still gives a
whopping 94% of the capacity it had when I bought it! Awesome battery, I
think I let the new one go 5-6 years and see how it performs.
Dean Psiropoulos
RV-6A N197DM
Going on 5 fun filled years
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