Today's Message Index:
----------------------
1. 06:36 AM - Re: Aeroled wiring (Eric M. Jones)
2. 10:02 AM - Lithium batteries redux (Robert L. Nuckolls, III)
3. 10:23 AM - Re: Re: Aeroled wiring (Robert L. Nuckolls, III)
4. 10:50 AM - Narco 11 connector source ()
5. 11:35 AM - Re: Substitute Midi Fuse instead of ANL Fuse (Robert L. Nuckolls, III)
6. 11:36 AM - Re: Narco 11 connector source (Robert L. Nuckolls, III)
7. 01:49 PM - Re: Substitute Midi Fuse instead of ANL Fuse (user9253)
8. 02:21 PM - Re: Lithium batteries redux (Robert Borger)
9. 03:43 PM - Re: Lithium batteries redux (Jan de Jong)
Message 1
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| Subject: | Re: Aeroled wiring |
Being completely ignorant of the Aeroled system and wiring....
Noise in Electrical Circuits 101:
1) Saving a dollar in pcb design often generates problems that take thousands of
dollars to solve in the field. (Hard-won wisdom.)
2) In my opinion, using a two layer PCB in a low-noise design is insane, unless
it can be proven that it works as well as a 4-or-more layer board.
3) Sharp-edged signals have their place in extremely small, extremely low-power
logic, but not in power supplies beyond what is needed to keep the thermal issues
under control and the parts' size and cost manageable.
4) Minimize clock traces and clock trace power, and clock signal edges.
5) Control noise at the source. Always.
Noise in strobes: Whelen designed their venerable strobe units long ago. The strobe
energy was stored in caps right at the beefy master-supply-strobe-sync unit.
Today, especially for LEDs the strobe energy is best accumulated right at
the discharge point (Supercaps?) to reduce noise issues and wiring size. Power
to the strobes should be entirely DC with the sync signal generated by any number
of simple means that won't generate an audio tick.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=391799#391799
Message 2
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| Subject: | Lithium batteries redux |
This morning's news included a bit concerning
a battery fire in a B787 on the ramp at Boston
airport.
http://tinyurl.com/bx3ww23
According to Skip Koss (and unlike the
Cessna ramp fire in the Citation) this fire appears
to have been controlled by individuals both trained
and equipped for dealing with a lithium fire.
A123 (manufacturer of the cells in the Cessna
battery) is shut down in bankruptcy although
I understand they've been purchased by a Chinese
interest.
Folks. I think it's pretty clear that the large
energy storage lithium products are not ready for
prime time on airplanes. There's a lot of ground
based history being made and new product development
being conducted which may ultimately evolve into
products with aviation-grade failure modes and risks . . .
let us wait and see.
Sometimes, the best way to drive a nail is with
a hammer and the best way to carry a reserve of
electrons is with lead-acid.
http://tinyurl.com/3atma44
Bob . . .
Message 3
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| Subject: | Re: Aeroled wiring |
At 08:35 AM 1/8/2013, you wrote:
Being completely ignorant of the Aeroled system and wiring....
Noise in Electrical Circuits 101:
1) Saving a dollar in pcb design often generates problems that take
thousands of dollars to solve in the field. (Hard-won wisdom.)
2) In my opinion, using a two layer PCB in a low-noise design is
insane, unless it can be proven that it works as well as a 4-or-more
layer board.
. . . . or has been proven adequate by DO-170/Mil-STD-462
testing.
3) Sharp-edged signals have their place in extremely small, extremely
low-power logic, but not in power supplies beyond what is needed to
keep the thermal issues under control and the parts' size and cost manageable.
4) Minimize clock traces and clock trace power, and clock signal edges.
5) Control noise at the source. Always.
Noise in strobes: Whelen designed their venerable strobe units long
ago. The strobe energy was stored in caps right at the beefy
master-supply-strobe-sync unit. Today, especially for LEDs the strobe
energy is best accumulated right at the discharge point (Supercaps?)
to reduce noise issues and wiring size. Power to the strobes should
be entirely DC with the sync signal generated by any number of simple
means that won't generate an audio tick.
It's not yet clear as to the nature of the
offending emission. The filter needed for
integrating the Luxdrive products addressed
a poorly managed radio frequency issue. This
spectrum of potential interference IS covered
by DO-160, Paragraph 21.3
The 'tick' cited by several writers is probably
a conducted, fast rise current transient coming
out on the power lines. This is a very low energy
event at an audio rate and with imperceptible
radio frequency components.
DO-160 DOES have a test for SUSCEPTIBILITY to low energy
spikes (used to be called the chattering relay
test . . . in fact, early bench test fixtures did
indeed use a 'buzzing' relay as a noise generator).
But it doesn't speak to kind of noise EMISSION that might
generate the 'tick'. There are LOTS of devices that
generate transients that might 'tick' . . . landing
light turn on, pitot heat turn on, landing gear motor
inrush, etc. Folks tend to ignore these due to their
intermittent, one-time occurrence. But when it happens
continuously in sync with repetitive operations like
wig-wag or strobe, it's another matter.
This is a new condition that has not yet be addressed
by codification . . . the manufacturers of guilty
product would do well to jump on this and fix it
before the bureaucrats decide to step in and help.
Bob . . .
Message 4
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| Subject: | Narco 11 connector source |
Does anyone have the part number or a source for the 15 pin connectors on the back
of a Narco 11A? I am planning on putting a TKM in the tray but the current
connector has broken into pieces. I am hoping I can get one cheaply from Mouser
or Digikey or someplace similar.
Message 5
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| Subject: | Re: Substitute Midi Fuse instead of ANL Fuse |
At 04:12 PM 1/7/2013, you wrote:
A friend of mine, Larry, wants to use a Midi Fuse instead of an ANL
to protect the battery and wires from a possible shorted
alternator. His Viking engine comes with a 40 amp alternator. The
Midi Fuse is physically smaller than the ANL and will take up less
room on his crowded firewall.
Question 1: Is it OK to use a Midi Fuse for this application?
Absolutely. There are several variations on the
ANL theme found in all manner of DC power systems
that range from the 'fusible link' up to and including
the legacy ANL/ANN style current limiters. This
would included devices like the Littlefuse MIDI
The data sheet you linked was for the BF1 which
is closer to a fuse than a current limiter.
Compare the specs found here and you'll see
that operating times versus current for the
BF1 fuse is asymptotic to a value close to
its rating while the MIDI is more like a
current limiter where the asymptote is much
greater than the device rating.
http://tinyurl.com/by5qnop
None the less all variations on this them are suitable
to your task.
Question 2: Should a 40 or a 50 amp fuse be used?
Keep in mind that the rating of an alternator
is for worst case conditions. A cold alternator
is capable of significantly more than rated output
until it warms up. Hence the condition known as
the "B-lead breaker designed to nuisance trip"
which describes the use of 60A breakers on
60A alternators on thousands of TC aircraft.
You'll notice that the fusing specs for these
these Littlefuse BF1 are not as robust as the
legacy current limiter. I note that Littlefuse
calls these devices 'fuses' as opposed to
'current limiters'. You will note too that
the BF1 has a few parts tagged with "Note 3"
suggesting that these parts should be used for
short circuit protection only . . . more
like their MIDI cousins.
The short answer is that one would do well to
use a substantially larger BF1 FUSE on the 40A
machine . . . 70A would not be out of line.
A MIDI-50 (almost a current limiter) would
be okay too.
Bob . . .
Message 6
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| Subject: | Re: Narco 11 connector source |
At 12:49 PM 1/8/2013, you wrote:
>
>Does anyone have the part number or a source for the 15 pin
>connectors on the back of a Narco 11A? I am planning on putting a
>TKM in the tray but the current connector has broken into pieces. I
>am hoping I can get one cheaply from Mouser or Digikey or someplace similar.
Do you have the pieces? Can you send me a photo
of the pieces and a view looking into the back
of the radio?
Bob . . .
Message 7
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| Subject: | Re: Substitute Midi Fuse instead of ANL Fuse |
Thanks for the info, Bob. I will pass it on to Larry.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=391840#391840
Message 8
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| Subject: | Re: Lithium batteries redux |
Bob,
You may very well be correct, but I've gone out on a limb that I trust will support
me and the aircraft.
I have purchased and installed an Aerovoltz 12 Cell EV02 LiFePo battery in my Europa.
The LiFePo battery is not supposed to be the fire hazard that the LiFe
battery is. It is amazingly small and light. About 12 lbs lighter than the
Odyssey it replaces.
I would not have done this had my Rotax 914 still been electric dependent with
two electric fuel pumps. about 2 years ago I replaced one of the electric pumps
with an engine driven, mechanical pump so the engine will continue to operate
should the electrics go totally dead.
So far, in 2 hours of testing on the ground and 1 hour in the air, all seems well.
It spins the Rotax on startup just like the Odyessy. I purchased the special
charger that will do fast, 5A, charge; slow. 2A, charge; maintenance, .1A,
charge/float and cell balancing. I have not done any time/power testing. I
need to see how long it will run the radio, transponder and GRT EIS 4000 and
then test with only the radio and EIS. When this is done, I will report the results.
The seller of the battery did warn not to discharge below 9v as that would probably
permanently damage the battery. And if discharged to below 11 volts, it
must be recharged in the cell balance mode.
Isn't this one reason why we call it Experimental?
Blue skies & tailwinds,
Bob Borger
Europa XS Tri, Rotax 914, Airmaster C/S Prop.
Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP
3705 Lynchburg Dr.
Corinth, TX 76208-5331
Cel: 817-992-1117
rlborger@mac.com
On Jan 8, 2013, at 12:00 PM, "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
wrote:
This morning's news included a bit concerning
a battery fire in a B787 on the ramp at Boston
airport.
http://tinyurl.com/bx3ww23
According to Skip Koss (and unlike the
Cessna ramp fire in the Citation) this fire appears
to have been controlled by individuals both trained
and equipped for dealing with a lithium fire.
A123 (manufacturer of the cells in the Cessna
battery) is shut down in bankruptcy although
I understand they've been purchased by a Chinese
interest.
Folks. I think it's pretty clear that the large
energy storage lithium products are not ready for
prime time on airplanes. There's a lot of ground
based history being made and new product development
being conducted which may ultimately evolve into
products with aviation-grade failure modes and risks . . .
let us wait and see.
Sometimes, the best way to drive a nail is with
a hammer and the best way to carry a reserve of
electrons is with lead-acid.
http://tinyurl.com/3atma44
Bob . . .
Message 9
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| Subject: | Re: Lithium batteries redux |
My assessment sofar (FWIW).
The problem with LiFePO4 batteries is that they do not self-balance
well. And the 4 cells are not reliably identical. The result is as follows.
You can either keep the cells balanced in the charged state, meaning
that none of the four will ever go over 4 volts when the battery is
charged at 14.4 V or so.
Or you can keep them balanced in the discharged state, meaning that none
of the four will ever be driven below 2 volts when the battery is
discharged to below 12 volts.
You cannot have both without sophisticated power electronics.
In our type of use we keep the battery balanced in the charged state.
The danger then lies in deep discharging.
I will only use LiFePO4 if I can have a battery alarm that goes off when
any one of the 4 cells goes below 2 volts (when discharging) or above 4
volts (when charging). And an alternative source of backup energy if
either occurs.
I would like to know in the meantime what level of battery monitoring is
done on the accident Cessnas and Dreamliners...
Jan de Jong
On 1/8/2013 11:20 PM, Robert Borger wrote:
>
> Bob,
>
> You may very well be correct, but I've gone out on a limb that I trust will support
me and the aircraft.
>
> I have purchased and installed an Aerovoltz 12 Cell EV02 LiFePo battery in my
Europa. The LiFePo battery is not supposed to be the fire hazard that the LiFe
battery is. It is amazingly small and light. About 12 lbs lighter than the
Odyssey it replaces.
>
> I would not have done this had my Rotax 914 still been electric dependent with
two electric fuel pumps. about 2 years ago I replaced one of the electric pumps
with an engine driven, mechanical pump so the engine will continue to operate
should the electrics go totally dead.
>
> So far, in 2 hours of testing on the ground and 1 hour in the air, all seems
well. It spins the Rotax on startup just like the Odyessy. I purchased the special
charger that will do fast, 5A, charge; slow. 2A, charge; maintenance, .1A,
charge/float and cell balancing. I have not done any time/power testing.
I need to see how long it will run the radio, transponder and GRT EIS 4000 and
then test with only the radio and EIS. When this is done, I will report the
results.
>
> The seller of the battery did warn not to discharge below 9v as that would probably
permanently damage the battery. And if discharged to below 11 volts, it
must be recharged in the cell balance mode.
>
> Isn't this one reason why we call it Experimental?
>
> Blue skies & tailwinds,
> Bob Borger
> Europa XS Tri, Rotax 914, Airmaster C/S Prop.
> Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP
> 3705 Lynchburg Dr.
> Corinth, TX 76208-5331
> Cel: 817-992-1117
> rlborger@mac.com
>
> On Jan 8, 2013, at 12:00 PM, "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
wrote:
>
>
> This morning's news included a bit concerning
> a battery fire in a B787 on the ramp at Boston
> airport.
>
> http://tinyurl.com/bx3ww23
>
> According to Skip Koss (and unlike the
> Cessna ramp fire in the Citation) this fire appears
> to have been controlled by individuals both trained
> and equipped for dealing with a lithium fire.
>
> A123 (manufacturer of the cells in the Cessna
> battery) is shut down in bankruptcy although
> I understand they've been purchased by a Chinese
> interest.
>
> Folks. I think it's pretty clear that the large
> energy storage lithium products are not ready for
> prime time on airplanes. There's a lot of ground
> based history being made and new product development
> being conducted which may ultimately evolve into
> products with aviation-grade failure modes and risks . . .
> let us wait and see.
>
> Sometimes, the best way to drive a nail is with
> a hammer and the best way to carry a reserve of
> electrons is with lead-acid.
>
> http://tinyurl.com/3atma44
>
>
> Bob . . .
>
>
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