Today's Message Index:
----------------------
1. 04:09 AM - Re: Battery Choices - what is too small AH capacity? (Beemer)
2. 07:34 AM - Re: Re: Battery Choices - what is too small AH capacity? (Ken)
3. 12:09 PM - Re: Battery Choices - what is too small AH capacity? (mikef)
4. 12:17 PM - Re: Battery Choices - what is too small AH capacity? (mikef)
5. 01:20 PM - Re: Battery Choices - what is too small AH capacity? (mikef)
6. 04:21 PM - Re: Re: Battery Choices - what is too small AH capacity? (Ken)
7. 04:33 PM - Re: Re: John Deere dynamo (Robert L. Nuckolls, III)
8. 04:34 PM - Re: EV200 (Robert L. Nuckolls, III)
9. 05:32 PM - Re: Re: I-Phone Inclinometer (John W Livingston)
10. 05:59 PM - Re: Re: Battery Choices - what is too small AH capacity? (Sam Hoskins)
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| Subject: | Re: Battery Choices - what is too small AH capacity? |
Mike,
I have the same question for my Kitfox with a G10 Suzi, I am planning to install
Z-19RB, and have issues with weight. Right now, I'm planning on installing a
17ah in the tail for the Primary Eng bus, and a 12ah behind the seat for the
Secondary bus.
My real question is how long will they last once the alt goes dead? no way to know,
unless we figure out how much amperage the ECM, coil, and fuel pump are using.
Right now, I have no idea.
I suppose it's a situation where an 8ah and a 12ah, or two 8ah would work, but
would it leave enough time, say 15-30 minutes to descend and reach an airport?
No idea.
I don't want to carry more weight than I have to, but I don't want to design in
an off-field landing, either. I guess if we were to figure out how much juice
is being used to keep the engine alive, we could calculate the time given by
the battery size(s).
Sound right?
Bradley
--------
Beemer
KF2 (and now an M3!)
Middle Georgia
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=198343#198343
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| Subject: | Re: Battery Choices - what is too small AH capacity? |
Obviously current draw is a critical number that is best measured by
you. However in general the number for most auto engines is in the 8 to
15 amp range from what I've seen for 3 or 4 cyl. engines. Higher with
some EFI engines. Perhaps a bit less with a carb. and gravity fuel feed.
The cruise number may be significantly higher than at idle. I would
expect there are some Suzi users that have measured this.
If you have independent low voltage warning and change out the battery
every two years, I still would not count on more than 50% of rated
energy out of a battery. ie 4AH out of an 8AH battery which means be on
the ground within 15 min. with an 8 AH battery and a 15 amp load.
Regular battery capacity testing might extend that a bit but I don't
know anyone who does that. Testing at the required load or running the
engine at cruise rpm until it quits will tell the story with some
further degradation as the battery ages. In extreme temperatures, don't
count on even 50% capacity. The battery AH rating is usually for a lower
current than you will need, so you can't count on gettng 8AH of useful
energy out of an 8AH rated battery even at room temperature.
Ken
Beemer wrote:
>
> Mike,
> I have the same question for my Kitfox with a G10 Suzi, I am planning to install
Z-19RB, and have issues with weight. Right now, I'm planning on installing
a 17ah in the tail for the Primary Eng bus, and a 12ah behind the seat for the
Secondary bus.
>
> My real question is how long will they last once the alt goes dead? no way to
know, unless we figure out how much amperage the ECM, coil, and fuel pump are
using. Right now, I have no idea.
>
> I suppose it's a situation where an 8ah and a 12ah, or two 8ah would work, but
would it leave enough time, say 15-30 minutes to descend and reach an airport?
No idea.
>
> I don't want to carry more weight than I have to, but I don't want to design
in an off-field landing, either. I guess if we were to figure out how much juice
is being used to keep the engine alive, we could calculate the time given by
the battery size(s).
>
> Sound right?
> Bradley
>
> --------
> Beemer
> KF2 (and now an M3!)
> Middle Georgia
>
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| Subject: | Re: Battery Choices - what is too small AH capacity? |
Ken,
Your conservative approach is probably a good one to begin estimating. I plan to
experiment with actual battery only run times to back up the theory.
I am also thinking about purchasing one of those West Mountain battery testers.
At $109 it is probably money well spent. I know we go on forever with the 'little
extras' in OBAM but I don't want to be looking for a field and thinking 'damn,
just $109.....' .
Mike
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=198424#198424
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| Subject: | Re: Battery Choices - what is too small AH capacity? |
Ken and others,
That is good info on the battery usage. I'll look into the Dekka, I especially
like the larger battery contacts as compared to the PC310 M4 bolts (they are so
small they can hardly be called bolts....). I also replied in another thread,
that I think the purchase of the West Mountain battery tester is probably money
well spent (or something similar bought or built). Auto conversion guys like
me need to know that if the alternator goes south, there really is a backup
of some duration.
Bob K has good guidelines for determining battery capacity, and I think taking
the extra step with a quantitative measure is good.
Fly safe,
Mike
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=198427#198427
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| Subject: | Re: Battery Choices - what is too small AH capacity? |
Ken,
You wrote: 8 AH Dekka AGM batteries
Can you describe the battery terminals on these Dekka batteries? Even a digital
photo would be helpful. I have #2 welding cable with #2 lug terminals from the
main contactor to the main battery terminals. I'm a bit concerned my existing
battery terminals are too small for long term use & vibration resistance.
Thanks,
Mike
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=198438#198438
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| Subject: | Re: Battery Choices - what is too small AH capacity? |
They are 3/16" bolts I believe. Might be a metric size and a bit larger
but the bolts come with the battery. I have #4 welding cables on them
which they are quite suitable for. Should be some pics on the Dekka
site. They are made by East Penn battery in PA I think. I picked up the
cable end terminals from a marina. I doubt there is an advantage to #2
cables on these little batteries unless you have a very long cable run.
They are sturdy terminals but obviously smaller cables stress them less.
Ken
mikef wrote:
>
> Ken,
>
> You wrote: 8 AH Dekka AGM batteries
>
> Can you describe the battery terminals on these Dekka batteries? Even a digital
photo would be helpful. I have #2 welding cable with #2 lug terminals from
the main contactor to the main battery terminals. I'm a bit concerned my existing
battery terminals are too small for long term use & vibration resistance.
>
> Thanks,
>
> Mike
>
Message 7
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| Subject: | Re: John Deere dynamo |
At 06:38 AM 8/12/2008 -0700, you wrote:
>
>
>nuckolls.bob(at)cox.net wrote:
> > At 07:52 AM 8/11/2008 -0700, you wrote:
> >
> > > >>>Can you give us your perceptions of "weakness"?
>
>Only what I've read of your attitude/opinion (for lack of a better term)
>on them around the list. Correct me if I'm wrong, but I get the overall
>impression that you do not believe IR alternators belong on aircraft.
That's a popular myth promulgated mostly by two individuals
who are demonstrably un-qualified to judge my work.
They appear to have never read and/or understood design
goals I (and hundreds of my colleagues) have embraced as
aircraft system integrators and component designers for 30+ years.
> Of course, it is possible that you don't agree with how John Q Builder
> tends to install them, i.e. no OV protect, no Alt disconnect contactor,
> etc. I get this from some old postings on the subject, and the deletion
> of any schematics that show IR alternator installations. I should add
> that there isn't much available for my type of engine (Geo Metro auto
> conversion), and weight is a significant issue up on the nose of the Kitfox.
I'm not sure you understand the spirit and intent of
my offerings here on the List and elsewhere. I think we
can agree that airplanes, with all the potential for
utility and pleasure, are exceedingly unforgiving machines.
The environment in which we operate them can be equally
unforgiving. Everything I've bolted to an airplane has
these design goals in mind. (1) Utility (function as
specified/advertised). (2) Weight. (3) Cost of ownership.
and last but not least (4) Risk Mitigation.
In categories 1-3, the stock automotive alternator is
a stellar performer and quite suited to the task aboard
airplanes but with two shortcomings"
In the category of UTILITY: ON/OFF control at any time
under any conditions without risk to itself or other
components in the system. This is how alternators/generators
have functioned in aircraft since day-one. There are both
operational and risk mitigation advantages for giving the pilot
and OV protection systems a means of managing alternator operations . . .
and RISK MITIGATION: I have seen no design to data for
which the risk of OV runaway is zero. Further, the potential
for a high-energy even in a runaway alternator is significant.
See:
http://aeroelectric.com/articles/When_is_110V_not_Over_Voltage.pdf
Since day one in aircraft, independent monitoring of bus voltage
COMBINED with the ability to shut an alternator/generator off
at will relieves the system designer of a time-consuming
and costly effort of designing, proving and maintaining a system
reliability in the 10-to-the-minus-9-failures-per-flight-hour
category (FAA-speak for 'never happens').
Failure tolerance is integral to every design and goes directly
to both Cost of Ownership and Risk Mitigation.
Example: I'm working on a line of smart actuators that communicate
on serial data busses, move flight surfaces, and while failure to
move does not generate a serious situation for aircraft and
crew, a failure that produces an un-commanded is bad. The neat
thing is that there are flight systems management computers
on all these aircraft that control everything. Hence Level-A
qualification for software. Normally, an actuator such as
we've proposed would require Level-A qualification too . . .
except.
Since Level-A software already exists that sends me commands
and monitors my response to those commands, all I need to
do is place the entire monitoring duties on the machines already
endowed with the ability to monitor abnormal behavior. I
provide a hard discrete enable line to that computer that
actually powers the level shifters between low level logic
and the motor drivers. If that 28v disappears, the actuator
cannot move.
Now, my software can be crafter to Level-C or even Level-D
because it has no ability to generate hazardous conditions
that are not already being monitored and controlled by another
part of the system qualified to Level-A.
By making my part of the program failure tolerant without
adding risk to the overall flight system, costs of ownership
goes down, and parts-count goes down (driving reliability
up). But even if my gizmo craps every 1000 hours, it's not
a safety of flight issue - only a cost of ownership issue.
>
> > >>> ??? I got lost here. Z-24 speaks to classic,
> > >>>wound field alternators like ND . . . are you
> > >>>looking for a wound field or permanent magnet
> > >>>fielded machine?
>
>What I'm looking for, ultimately, is to shave about 10lbs from the nose of
>my aircraft. To that end, I'm exploring options for various components.
>More specifically, I'm looking for 20-40 reliable amps for my electrically
>dependent FI engine. Beyond that, I'm open to suggestions.
If I were building an airplane, it WOULD have a
stock automotive alternator with Z-24 installed as
an interim solution to get flying and laying the
ground work for installation of a permanent solution
at a later date as described in:
http://www.aeroelectric.com/articles/Adapting_IR_Alternators_to_Aircraft.pdf
>I was referring to the old Z-24 that depicted the alternator disconnect
>contactor for the IR alternator, driven by the alt field wire, that
>completely disconnects the alternator from the battery (system) in case of
>OV condition. That's what I'm running now on my current install. The note
>on the new Z-24 again leads me to believe you are not in favor of IR
>alternators on aircraft. Again, correct me if I'm wrong here.
Why would I have even crafted Z-24 if I were attempting
to quash the use of IR alternators? And why would I
follow up the Z-24 interim with the new-and-improved
alternative? I'll suggest that these two drawings are
a positive if not enthusiastic endorsement of the
value offered by a host of automotive alternator
products.
No, I have never said that IR alternators do not belong
on aircraft. I have said that I cannot RECOMMEND them because
the current state of our art does not allow me to integrate
them in satisfaction of the design goals cited above.
Z-24 was a first crack at meeting those design goals.
It has some short comings which are discussed in detail in
publications on my website. Those short comings will
be addressed in due course.
>
> > >>> Mechanically, no problem. Raising the speed increased the
> > >>>AC voltage to be "rectified and regulated" down to
> > >>>14v for operating your equipment. There ARE switch-mode
> > >>>regulator designs that would handle this job nicely
> > >>> but that's a whole separate development program.
> >
>That's why I'm asking. I should point out that I'm not very
>electrically/electronically savvy (..got to know my limitations). That's
>why you, this list, and Aeroelectric.com are such valuable resources for
>me. I'm asking the advice of those much smarter than I on such things.
First, there are ways to make ANY selection of engine driven
power source suited to use in the aircraft environment.
Further, if you choose not to embrace my design goals, then
there is still good value to be received from bolting a stock
automotive alternator to your airplane. As long as you
understand and accept the risks and perhaps lack of utility
compared to the majority of the GA fleet, then I have
no heartburn with it. But if you're being mis-advised into
believing there is little or no increased risks as
compared to contemporary aircraft design philosophies,
you owe it to yourself to at least elevate your understanding
to the level needed to make a well considered decision.
Don't do anything based on my (or anyone else's recommendations)
unless you understand and personally embrace the design
goals that go along with those recommendations.
>My electronics are minimal. I'm running an EFIS that draws about 100mA
>max, my GPS and Radio are handhelds that are plugged in to charge, and a
>small portable intercom. I've got Kuntzleman strobes and LED Navs, and two
>55watt landing lights. If it all dies, my pressure driven AoA gives me
>speed, and a ball keeps me centered, the rest is VFR (blue up/brown down).
>GPS gets me to "Nearest", and my radio will last a while all by itself.
>I'm strictly Day VFR, with no provision or desire to night or IFR. Night
>someday, NEVER IFR in this plane. So my number one concern is keeping the
>EFI and fuel pump running. My new plane will have Z-13RB installed to this
>end. I don't even plan to put in the endurance bus, as I've got nothing
>that needs it. It even works to the end of having the second small battery
>in the back to help offset the CG of the heavier engine, rather than just
>putting in dead weight.
Sounds like a 3.5# SD-8 would do nicely for you. There are
thousands of LongEz and VariEz aircraft flying with this
machine as the only source of engine driven power.
>In the end, I think the JD dynamo will not be cost effective. For what
>they cost, I'd be shelling out $40 per lb for the weight savings. Probably
>not worth it overall.
But if you wanted to put a little 35 or 40A wound
field alternator on, that would not be a bad
decision either . . . internally or externally
regulated.
Let's channel this discussion toward establishing
your design goals and then meeting them. Please set
aside any notions that I or anyone else here on the
list is going to twist your arm to do anything except
perhaps those things which are overtly foolhardy or
dangerous.
Have you completed a load analysis of just what
your energy requirements are?
See:
http://www.aeroelectric.com/PPS/Load_Analysis/Blank_Form.pdf
This form is designed to facilitate a study of your
true energy needs. Until those are known, may I
suggest that alternator selection for the purpose
of minimizing weight is premature?
Bob . . .
Message 8
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At 10:42 AM 8/12/2008 -0400, you wrote:
>
>To 'Mikef', Harley and Bob Borger:
> Many thanks for having come back so quickly to my request.
> I tried to acquire an EV200 with the coil control which allows it to
>reduce to 1.7W of hold current in light of an apparent shortage of output
>from my 914. I fiddled with several race-car shut-off switches to conserve
>current, because I just couldn't afford 1A for the life of the plane.
>Finding the right model was difficult as mods and model revisions clouded
>the language. I now use the race-car switches and will operate one EV200,
>perhaps two to do the job.
> I have a GIGAVAC GX11BAA contactor in my palm right now, which takes
>about an amp to hold the relay in. Make me an offer.
> Again many thanks.
There's a simple circuit you can add to the Gigavac that
will emulate EV-200 functionality -AND- with some judicious
design, will eliminate the noise issues associated with
the EV-200.
Bob . . .
Message 9
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| Subject: | Re: I-Phone Inclinometer |
I believe that all of these SS gyros use a vibrating beam and measure the
angular rate by measuring the twist induced by Coriolis force. See
"Vibrating structure gyro" in the Wikipedia.
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com]On Behalf Of Robert
L. Nuckolls, III
Sent: Monday, August 11, 2008 6:45 PM
Subject: Re: AeroElectric-List: Re: I-Phone Inclinometer
<nuckolls.bob@cox.net>
At 06:20 AM 8/11/2008 -0700, you wrote:
>
>Etienne,
>SS Gyros are in fact MEMS accelerometers.
>Actually SS Gyro is an oxymoron since a gyro implies gyroscopic
>which implies spinning parts (hard to be solid state at the same time).
Correct. The devices are not accelerometers but rotational
rate sensors. Same sensed stimulus that your turn/bank
or turn-coordinator responds to.
>See: http://en.wikipedia.org/wiki/MEMS_gyroscope
>http://www.sensorsmag.com/articles/0203/14/
>http://www.analog.com/en/mems-and-sensors/imems-gyroscopes/adxrs610/product
s/product.html
>
>etc., etc.
>
>To my knowledge, the inertial platforms of BMA, Dynon, Avidyne (entegra),
>and Garmin (G1000) are all MEMS-based. No Gyro components at all.
>
>See for
ref:http://www.flyingmag.com/article.asp?section_id=12&article_id=869
>
>or look up the tech specs on the individual systems.
There are a variety of MEMS sensors responsive to
apparent gravity vectors which ARE true accelerometers.
There are a number of "digital inclinometers" on the market
that utilize two and three axis sensors of this variety.
Unlike precision accelerometers of yesteryear, these things
have a frequency response that goes down to DC. Imminently
suited to inclinometer service.
The rotational rate sensors are finding their way into
high-end GPS receivers to resolve vehicular turning
rate to let the guidance software know that you've
REALLY turned the corner it suggested. Less expensive
units need several seconds of new GPS data to resolve a
new course over the ground to confirm that the turn was
made.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 10
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| Subject: | Re: Battery Choices - what is too small AH capacity? |
I purchased one of the West Mountain units for the same reason that you are
concerned about, Mike. It's a nifty tool.
I was surprised to find the 11 a.h. battery I had laying around the shop was
actually only good for 7 a.h.
Sam
On Wed, Aug 13, 2008 at 2:06 PM, mikef <mikefapex@gmail.com> wrote:
>
> Ken,
>
> Your conservative approach is probably a good one to begin estimating. I
> plan to experiment with actual battery only run times to back up the theory.
>
> I am also thinking about purchasing one of those West Mountain battery
> testers. At $109 it is probably money well spent. I know we go on forever
> with the 'little extras' in OBAM but I don't want to be looking for a field
> and thinking 'damn, just $109.....' .
>
> Mike
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=198424#198424
>
>
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