Today's Message Index:
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1. 06:11 AM - Re: Re: Lightweight rechargeable battery backup unit (Robert L. Nuckolls, III)
2. 09:16 AM - Re: Klixon Circuit Breaker (William Hunter)
3. 09:18 AM - Re: Re: Lightweight rechargeable battery backup unit (The Kuffels)
4. 02:04 PM - Re: Klixon Circuit Breaker (Robert L. Nuckolls, III)
5. 03:32 PM - Re: Re: Lightweight rechargeable battery backup unit (Robert L. Nuckolls, III)
6. 03:34 PM - Re: Klixon Circuit Breaker (Robert L. Nuckolls, III)
Message 1
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Subject: | Re: Lightweight rechargeable battery backup unit |
At 05:32 PM 3/26/2017, you wrote:
>
>Bob,
>
>As far as I can see , the instrument itself has no facility for
>battery backup input, just the normal power feed
>http://www.mglavionics.co.za/Infinitec/Manuals/ASX1.pdf
neat gizmo . . . does lots of interesting
things.
>I therefore think the options are
>
>1) go with a commercial device that has been suggested on the Europa Forum
>http://www.mini-box.com/picoUPS-120-12V-DC-micro-UPS-battery-backup
>with a small backup battery such as this
>http://www.zbattery.com/Batteries/List-of-All-12Vs
>2) build my own unit, as suggested in the post by user9253 (Joe
>Gores) in the original thread
>3) Buy one of the more expensive units from either Funkework or LX
>Navigation with the battery backups built in
>4) stick with the steam driven ASI and Altimeter.
A standby battery is more a bureaucratic
philosophy than a strong mitigation of risk . . .
as an OBAM aircraft operator, it's pretty
much a given that you're going to fly with
an artfully maintained electrical system . . .
especially the battery. You will KNOW what
your battery-only endurance values are for
a pre-determined load which would, of course,
included the 50mA max demand of the ASX1.
It seems the practical need is to comply with
requirements and demonstrate a 'back up battery'
and offer an analysis of its performance and
a rational plan for insuring continued airworthiness.
I note that the ASX1 doesn't have a power switch
built in, so you not only need to provide a little
bundle of watt-seconds, you also need to manage
isolation that source when the ship is powered down.
Consider this:
Emacs!
>I guess my priorities are accuracy, minimum weight, and cost in that order
>
>I would value your opinion.
The legacy, alkaline 9v battery has a nominal
energy rating on the order of 500mAH. Suggest two
such batteries in series for a nominal operating
output of 16v falling to 12v at end of life.
The reason for suggesting these devices is their
WIRING. You can purchase snap-clips that make
good connection with the batteries. The 'ideal' cell
for a tiny DIY standby battery is the alkaline AA.
But battery trays for cylindrical cells are rather
flakey under environmental stress and you can't
routinely buy AA cells with welded tabs for low risk
soldering.
The schematic above shows two steering diodes that
insure power to the ASX1 from EITHER source
when the switch is closed. You need the switch to
(1) eliminate drain on the standby battery when
parked and (2) facilitate pre-and-post flight
testing of the installed batteries.
Your check-list would turn the ASX-1 on FIRST
to show that the device comes alive on the standby
battery. Then bring ship's power up and proceed
as you normally would.
The ASX-1 would be turned off last . . . again
showing that the battery is at least capable of
powering the instrument.
Requirements for continued air-worthiness would
simply call for replacing the batteries every year.
The alkaline cell will loose about 15% of capacity
in first year if stored at about 120F.
I stuck one of these batteries on the WestMountain Radio
Battery-runner-downer and it tells me that when the
fresh battery is loaded at 40mA (I de-rated from the
13.8V/50mA value in the manual . . . we're battery operating
at a slightly higher voltage into a constant power
demand).
Emacs!
The fresh Duracell 9v delivered a solid 2 watt-hours at the
40mA rate. A pair of cells would be 4 watt-hours. At 14v
the specified demand of the ASX1 with the display illuminated
is 14v x 0.05A or 0.7W.
Hence, the pair of Duracell 9v batteries can be expected
to carry the instrument solidly for 6 hours . . . for
4+ hours at end of year assuming storage at elevated
temperatures.
The installed weight of this system would be under 0.3 pounds.
The bill of materials cost would be on the order of $10 which
includes the first year's compliment of batteries.
Continued air worthiness burden would be on the order of
$4/year assuming Sam's club prices for the 9v batteries.
Best yet, there is no burden of labor to verify the capacity
of a rechargeable back up system.
The FMEA looks good . . . the system gets pre and post-flight
tested.
This would seem to be the minimalist approach to meeting
the regulatory demand for a back up system that is, like a circuit
breaker, exceedingly unlikely to ever see real service.
Bob . . .
Message 2
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Subject: | Re: Klixon Circuit Breaker |
Hi Bob, thanks (as always) for your advice!
I already have two circuit breaker holes (one labeled "gear control" and
the other one labeled "gear hydraulic" and therefore I was trying to figure
out some way to salvage this mess and make it look like it it's supposed to
be that way.
So it looks like what I should do is simply remove this 30 amp circuit
breaker and cover up its laser etched label with some sort of black paint
or happy face sticker or something to make it look like it wasn't there.
I know you stated "current limiter" in your reply however is an automotive
automatically reseting inline circuit breaker sufficient for airplane use
or should it be a real slow blow one shot for real current limiter?
Bill Hunter
On Mar 26, 2017 08:46, "Robert L. Nuckolls, III" <
nuckolls.bob@aeroelectric.com> wrote:
At 07:31 PM 3/25/2017, you wrote:
Hi all,=C3=82
I have a slight spacial conflict problem with the instrument panel design
and I need a smaller circuit breaker.=C3=82
I designed my instrument panel with a row of circuit breakers and I have
already had the instrument panel holes drilled and the silk screening done
for the circuit breaker labels. My landing gear hydraulic motor requires a
30 amp circuit breaker and I placed it's 30 amp Potter and Brumfield
W23-x1a1g-30 circuit breaker on the end of the row however I discovered
that I have a slight space conflict to the point where the Potter and
Brumfield circuit breaker will not fit in its hole.=C3=82
I wouldn't bring this kind of
high current feeder up to the panel.
I'd use a current limiter at the battery
contactor thus keeping all the fat-wires
of the panel. If there's already a
spot for a breaker marked 'landing gear',
put a 5a breaker there to power the control
system.
Bob . . .
Message 3
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Subject: | Re: Lightweight rechargeable battery backup unit |
Bob,
Hesitate to display my ignorance but with the schematic you drew won't the
ASX-1 draw power from the higher voltage source, the batteries, until they
are depleted to below the E-bus voltage? Won't replacing the diodes and SP
ST switch with a SPDT (even an on - off - on) with the center contact going
to the ASX-1 solve the issue and provide the same functionality?
Tom Kuffel
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Message 4
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Subject: | Re: Klixon Circuit Breaker |
At 11:13 AM 3/27/2017, you wrote:
>Hi Bob, thanks (as always) for your advice!=C2
>
>I already have two circuit breaker holes =C2 (one
>labeled "gear control" and the other one labeled
>"gear hydraulic" and therefore I was trying to
>figure out some way to salvage this mess and
>make it look like it it's supposed to be that way.=C2
>
>So it looks like what I should do is simply
>remove this 30 amp circuit breaker and cover up
>its laser etched label with some sort of black
>paint or happy face sticker or something to make
>it look like it wasn't there.=C2
You could put a 5A breaker in there and use it
to POWER the coil on the hydraulic pump contactor . . .
>I know you stated "current limiter" =C2 in your
>reply however is an automotive automatically
>reseting inline circuit breaker sufficient for
>airplane use or should it be a real slow blow
>one shot for real current limiter?
>
>Bill Hunter
I recommend the mini-ANL devices now available
all over the 'net . . . and showing up in some
auto parts stores.
Here one example:
http://tinyurl.com/k4x4bua
Off the shelf holders for these fuses come
in TWO varieties (1) uses 'set screws' to mash
down on the fat-wires, ostensibly capturing
them in the end of the fuse holder . . . AVOID
THESE. (2) uses two threaded posts over which
the fuse is dropped along with the terminals
that bring fat-wires up to the fuse holder. Here's
one example . .
Emacs!
Obviously, you could make something like this yourself.
Get a piece of phenolic, delrin, lexan, etc, and cut
out a base. Drill 10-32 fuse mounting holes (counter bore
back side for electrical clearance to ground). A couple
more 6-32 attach holes. The cover is more cosmetic than
utilitarian.
Bob . . .
Message 5
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Subject: | Re: Lightweight rechargeable battery backup |
unit
At 11:16 AM 3/27/2017, you wrote:
>Bob,
>
>Hesitate to display my ignorance but with the schematic you drew
>won't the ASX-1 draw power from the higher voltage source, the
>batteries, until they are depleted to below the E-bus
>voltage? Won't replacing the diodes and SPST switch with a SPDT
>(even an on - off - on) with the center contact going to the ASX-1
>solve the issue and provide the same functionality?
>
>Tom Kuffel
Nothing ignorant about your observation my friend . . . good
eye! Your suggestion eliminates the conflict you noted.
Here's another alternative. The diodes prevent back-feeding
of either source to the opposite source. The switch
isolates the standby batteries.
Preflight would be modified to close the sb battery
switch first to see that the ASX-1 lights up. Then
turn it back off for remainder of that flight op.
Thanks for the catch!
Emacs!
Bob . . .
Message 6
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Subject: | Re: Klixon Circuit Breaker |
>
> Obviously, you could make something like this yourself.
> Get a piece of phenolic, delrin, lexan, etc, and cut
> out a base. Drill 10-32 fuse mounting holes (counter bore
> back side for electrical clearance to ground). A couple
> more 6-32 attach holes. The cover is more cosmetic than
> utilitarian . . .
P.S. Dug around and found some pix I'd taken
of an exemplar DIY Mini-ANL holder some years
ago . . .
http://tinyurl.com/mv2dq98
http://tinyurl.com/lvununh
http://tinyurl.com/m2tj9ux
http://tinyurl.com/mbmjoev
Bob . . .
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