Today's Message Index:
----------------------
1. 03:10 AM - Re: 14 v Gyro on a 12 volt sustem? (Gilles Thesee)
2. 06:12 AM - Re: Re: Small battery limited to 3 amp charge rate ? (Chuck Jensen)
3. 07:53 AM - Re: Concorde battery performance (Robert L. Nuckolls, III)
4. 08:02 AM - Re: Exploding Capacitors? (Robert L. Nuckolls, III)
5. 08:05 AM - Re: 14 v Gyro on a 12 volt sustem? (Robert L. Nuckolls, III)
6. 08:09 AM - Concorde versus Gill ()
7. 08:40 AM - Re: Re: Small battery limited to 3 amp charge rate ? (Robert Feldtman)
8. 09:10 AM - Z-20 Adaptation (ianwilson2)
9. 10:17 AM - Re: switch rating question (Vernon Little)
10. 01:11 PM - Re: Exploding Capacitors? (darinh)
11. 01:38 PM - Re: 14 v Gyro on a 12 volt sustem? (Don G)
12. 02:22 PM - Electrical System Reliability (and other ???) (FLAGSTONE)
13. 06:09 PM - Re: Z-20 Adaptation (Robert L. Nuckolls, III)
Message 1
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Subject: | Re: 14 v Gyro on a 12 volt sustem? |
Don G a crit :
>
> Gents,
> I am looking at Electric attitude gyros and I have a rotax 912 with a 12 v system
in my craft. My question is, will an insturment listed as a 14 volt perfom
ok on a 12 v system?
>
Don,
I installed electric gyros on a Rotax project.
The so-called '12V' Rotax alternator actually outputs about 13.8-14.2
volts. You'll have no problem, as long as the total current continuous
draw stays below 12 amps.
Best regards,
--
Gilles
http://contrails.free.fr
Message 2
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Subject: | Re: Small battery limited to 3 amp charge rate |
?
Bob F.
I amend my earlier posting and concur with Bob N.(I'll bet he feels
relieved). It looks like a system problem more than a battery problem.
Nonetheless, the Odyssey is a heck'va battery.
Chuck Jensen
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com]On Behalf Of Chuck
Jensen
Sent: Saturday, January 05, 2008 7:05 PM
Subject: RE: AeroElectric-List: Re: Small battery limited to 3 amp
charge rate ?
Bob,
Get a 680 or 925 Odyssey and be done with your worries. If its not a 6
cylinder, then the 680 should be ample for your needs. Highly and
uniformly recommended.
Chuck Jensen
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com]On Behalf Of Robert
Feldtman
Sent: Saturday, January 05, 2008 6:02 PM
Subject: Re: AeroElectric-List: Re: Small battery limited to 3 amp
charge rate ?
I'm getting sorta tired of replacing my Concorde attery in the Glastar
every 14 months or so cause they just won't hold a charge. I need
something more reliable than that. -- I know I know - avoiding long
times in between useage, cold weather, deep discharge (like starting)
short flights - all that stuff. Without getting into too much of a
commerical war - does folks have preferences for Concorde vs gill (now
Teledyne Continental) etc?
And yes I am using an off the shelf Auto zone recharger - maybe that is
the problem although it has the setting for different types and
automatic shutoff etc.
bobf
On 1/5/08, Robert L. Nuckolls, III < nuckolls.bob@cox.net> wrote:
nuckolls.bob@cox.net>
At 02:15 PM 1/5/2008 -0600, you wrote:
>Wondering how this works ? Help appreciated!
>
>I have a 7ah battery on a separate bus for EFIS(alternate power) that
is
>not directly connected to the main bus during starting or normal
>operations. However, I do have a charging circuit off the main bus
>through a D25 diode which should put 14.4 - .6 or 13.8 volts to the
small
>battery during normal operations to keep it charged. It is a fused
>circuit and intended to be hot anytime the main bus is on. That way
the
>Aux Bat should be always charged, available to run the EFIS before and
>during starting with no draw on it, and not drain back if the main bus
is
>off. And no switching required during normal ops.
>
>The Z35 Light Aux Bat
>figure
>< http://www.aeroelectric.com/PPS/DCPwr/Z35K_Light_Aux_Battery.pdf>
<http://www.aeroelectric.com/PPS/DCPwr/Z35K_Light_Aux_Battery.pdf>
http://www.aeroelectric.com/PPS/DCPwr/Z35K_Light_Aux_Battery.pdf
>is similar except that I think it is intended to be turned on after
>starting and not be available from before to after starting.
>
>My question: It was just pointed out to me that the 7ah battery has a
3
>amp charging limit (per B&C spec sheet) and I am wondering if there
should
>be a resistor in this circuit to limit the charging current? I see
that
>the full size batteries do not have a charging limit. Is there any
>danger if the smaller 7ah is fully discharged that it could draw enough
>charging current to damage it without a limiting resistor.
>
>If it does require a resistor for the small battery, wouldn't the same
>thing apply to the Z35 figure since you could easily have a fully
>discharged aux bat, start the airplane, and then hit the switch putting
>full current to the fully discharged battery?
The only time the recharge limit might be exceeded
is if the battery is connected to and alternator-supported
bus after being completely discharged. This should be a
rare event and you should be aware of it before it happens.
I.e., you were forced to use the aux battery sans alternator
until the battery was at or nearly depleted.
This scenario generates a maintenance event that includes
repairing the failed alternator and might as well include
putting a smart charger on the aux battery to GENTLY return
it to it's 100% state of charge.
On the rare occasion that you find it useful/necessary
to recharge the aux battery using ship's alternator, then
yes . . . the battery will see an out-of-spec recharge
rate for a short period of time. But we wouldn't expect
to see it happen often.
If you use this battery in a repeated charge/discharge mode
of operation . . . like to be the sole source of energy
for running a radio in a sailplane, then it's prudent and
even practical to acquire a recharging system that pampers
the battery for the purpose of extending service life.
However, in the case we're considering, the aux battery
may be replaced in an few years never having been deeply
discharged over the lifetime of its service. It's my
considered judgement that adding the extra gee-whiz
components for pampered recharge only adds to parts
count and pilot/maintenance workload and would contribute
no measurable increase in service life of the battery.
href="http://www.matronics.com/Navigator?AeroElectric-List">http://www.
matronics.com/Navigator?AeroElectric-List
href="http://forums.matronics.com">http://forums.matronics.com
href="http://www.matronics.com/contribution">http://www.matronics.com/c
Message 3
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Subject: | RE: Concorde battery performance |
At 09:04 AM 1/6/2008 -0500, you wrote:
>Bob F.
>
>I amend my earlier posting and concur with Bob N.(I'll bet he feels
>relieved). It looks like a system problem more than a battery
>problem. Nonetheless, the Odyssey is a heck'va battery.
>
>Chuck Jensen
Agreed! But event the best battery will produce
dismal performance if not operated within it's
design limits. This is why I suggested that he
get an el-cheeso Batteries-R-Us offering and see
if he can get some good life out of it. This will
happen only if he achieves an operating environment
favorable to batteries . . . of any pedigree.
Bob . . .
Message 4
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Subject: | Re: Exploding Capacitors? |
At 06:24 PM 1/5/2008 -0800, you wrote:
>
>I am building a Kitfox Series 7 and the wiring diagrams show the
>alternator lines being tied to a 22,000 microfarad, 25 V capacitor. This
>is installed on the output side of the regulator so I assume it is mainly
>for audio noise reduction in the system. My Rotax manual also recommends
>that I install a capacitor on each of the fuel pumps for the same
>reason. I am not an electronics guru but I do remember blowing up
>capacitors as a younger kid for fun. I remember we had to wire the
>capacitor with reversed polarity to get them to explode but even the small
>ones were pretty impressive to say the least! The one I have in my plane
>is huge in comparison to the small one I blew up as a kid and looks as if
>it could do some serious damage if it went.
>
>for you guys that know more than I do, do I need to be worried about this
>setup? And is there another alternative to the capacitor approach to
>minimize radio noise?
Capacitors of the style under discussion
have been used by the hundreds of millions
without serious danger to their users or
the equipment in which they are installed.
Capacitors . . . like batteries, propellers,
fuel lines, etc all offer some degree of hazard
when their operational characteristics and limits
are not dutifully observed.
The capacitors are not useful on your fuel
pumps. The capacitor is useful on your alternator
system. If installed with due diligence
to proper technique offers no extraordinary
risks to you or your airplane.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 5
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Subject: | Re: 14 v Gyro on a 12 volt sustem? |
At 12:08 PM 1/6/2008 +0100, you wrote:
><Gilles.Thesee@ac-grenoble.fr>
>
>Don G a crit :
>>
>>Gents,
>>I am looking at Electric attitude gyros and I have a rotax 912 with a 12
>>v system in my craft. My question is, will an insturment listed as a 14
>>volt perfom ok on a 12 v system?
>>
>
>Don,
>
>I installed electric gyros on a Rotax project.
>The so-called '12V' Rotax alternator actually outputs about 13.8-14.2
>volts. You'll have no problem, as long as the total current continuous
>draw stays below 12 amps.
I think his question was centered on the gyro,
not the alternator. He was getting wrapped around
the 12v battery vs 14v system axle.
Don, EVERY vehicle with a 12v battery in it operates
at around 14v when the alternator is producing as
designed. This is because to CHARGE a 12v battery,
you need to produce the energy at a voltage level that
exceeds the battery's voltage by some practical amount.
Any accessory designed and labeled as "12v" should
take this fact of physics into account. Chances
are that your "12-volt gyro" is going to be just
fine on your 14-volt airplane.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 6
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Subject: | Concorde versus Gill |
1/6/2008
Hello Robert Feldtman, Anecdotal information / experience leads me to prefer
Concorde over Gill. This opinion is supported by "The Aviation Consumer"
magazine in their Jan 2008 issue with some data.
You don't say whether you are useing flooded or VRSLA (Valve Regulated
Sealed Lead Acid) Concorde batteries. You might try the VRSLA version if you
have not already.
'OC' Says: "The best investment we can make is the effort to gather and
understand knowledge."
-------------------------------------------------------
Time: 03:03:37 PM PST US
From: "Robert Feldtman" <bobf@feldtman.com>
Subject: Re: AeroElectric-List: Re: Small battery limited to 3 amp charge
rate
?
I'm getting sorta tired of replacing my Concorde attery in the Glastar every
14 months or so cause they just won't hold a charge. I need something more
reliable than that. -- I know I know - avoiding long times in between
useage, cold weather, deep discharge (like starting) short flights - all
that stuff. Without getting into too much of a commerical war - does folks
have preferences for Concorde vs gill (now Teledyne Continental) etc?
And yes I am using an off the shelf Auto zone recharger - maybe that is the
problem although it has the setting for different types and automatic
shutoff etc.
bobf
Message 7
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Subject: | Re: Small battery limited to 3 amp charge rate |
?
Appreciate the valuable information - indeed the Odyssey looks super! I do
have a Fluke, which I trust - so will make the various measurements. Flad I
asked the question so the entire list can learn about this ever so common
problem with airplanes - battery problems! Main problem is I don't fly
enough!
bobf
On 1/6/08, Chuck Jensen <cjensen@dts9000.com> wrote:
>
> Bob F.
>
> I amend my earlier posting and concur with Bob N.(I'll bet he feels
> relieved). It looks like a system problem more than a battery problem.
> Nonetheless, the Odyssey is a heck'va battery.
>
> Chuck Jensen
>
> -----Original Message-----
> *From:* owner-aeroelectric-list-server@matronics.com [mailto:
> owner-aeroelectric-list-server@matronics.com]*On Behalf Of *Chuck Jensen
> *Sent:* Saturday, January 05, 2008 7:05 PM
> *To:* aeroelectric-list@matronics.com
> *Subject:* RE: AeroElectric-List: Re: Small battery limited to 3 amp
> charge rate ?
>
> Bob,
>
> Get a 680 or 925 Odyssey and be done with your worries. If its not a 6
> cylinder, then the 680 should be ample for your needs. Highly and uniformly
> recommended.
>
> Chuck Jensen
>
> -----Original Message-----
> *From:* owner-aeroelectric-list-server@matronics.com [mailto:
> owner-aeroelectric-list-server@matronics.com]*On Behalf Of *Robert
> Feldtman
> *Sent:* Saturday, January 05, 2008 6:02 PM
> *To:* aeroelectric-list@matronics.com
> *Subject:* Re: AeroElectric-List: Re: Small battery limited to 3 amp
> charge rate ?
>
> I'm getting sorta tired of replacing my Concorde attery in the Glastar
> every 14 months or so cause they just won't hold a charge. I need something
> more reliable than that. -- I know I know - avoiding long times in between
> useage, cold weather, deep discharge (like starting) short flights - all
> that stuff. Without getting into too much of a commerical war - does folks
> have preferences for Concorde vs gill (now Teledyne Continental) etc?
>
> And yes I am using an off the shelf Auto zone recharger - maybe that is
> the problem although it has the setting for different types and automatic
> shutoff etc.
>
> bobf
>
> On 1/5/08, Robert L. Nuckolls, III <nuckolls.bob@cox.net> wrote:
> >
> > nuckolls.bob@cox.net>
> >
> > At 02:15 PM 1/5/2008 -0600, you wrote:
> >
> >
> > >Wondering how this works ? Help appreciated!
> > >
> > >I have a 7ah battery on a separate bus for EFIS(alternate power) that
> > is
> > >not directly connected to the main bus during starting or normal
> > >operations. However, I do have a charging circuit off the main bus
> > >through a D25 diode which should put 14.4 - .6 or 13.8 volts to the
> > small
> > >battery during normal operations to keep it charged. It is a fused
> > >circuit and intended to be hot anytime the main bus is on. That way
> > the
> > >Aux Bat should be always charged, available to run the EFIS before and
> > >during starting with no draw on it, and not drain back if the main bus
> > is
> > >off. And no switching required during normal ops.
> > >
> > >The Z35 Light Aux Bat
> > >figure
> > ><http://www.aeroelectric.com/PPS/DCPwr/Z35K_Light_Aux_Battery.pdf>http://www.aeroelectric.com/PPS/DCPwr/Z35K_Light_Aux_Battery.pdf
> > >is similar except that I think it is intended to be turned on after
> > >starting and not be available from before to after starting.
> > >
> > >My question: It was just pointed out to me that the 7ah battery has a
> > 3
> > >amp charging limit (per B&C spec sheet) and I am wondering if there
> > should
> > >be a resistor in this circuit to limit the charging current? I see
> > that
> > >the full size batteries do not have a charging limit. Is there any
> > >danger if the smaller 7ah is fully discharged that it could draw enough
> > >charging current to damage it without a limiting resistor.
> > >
> > >If it does require a resistor for the small battery, wouldn't the same
> > >thing apply to the Z35 figure since you could easily have a fully
> > >discharged aux bat, start the airplane, and then hit the switch putting
> >
> > >full current to the fully discharged battery?
> >
> > The only time the recharge limit might be exceeded
> > is if the battery is connected to and alternator-supported
> > bus after being completely discharged. This should be a
> > rare event and you should be aware of it before it happens.
> > I.e., you were forced to use the aux battery sans alternator
> > until the battery was at or nearly depleted.
> >
> > This scenario generates a maintenance event that includes
> > repairing the failed alternator and might as well include
> > putting a smart charger on the aux battery to GENTLY return
> > it to it's 100% state of charge.
> >
> > On the rare occasion that you find it useful/necessary
> > to recharge the aux battery using ship's alternator, then
> > yes . . . the battery will see an out-of-spec recharge
> > rate for a short period of time. But we wouldn't expect
> > to see it happen often.
> >
> > If you use this battery in a repeated charge/discharge mode
> > of operation . . . like to be the sole source of energy
> > for running a radio in a sailplane, then it's prudent and
> > even practical to acquire a recharging system that pampers
> > the battery for the purpose of extending service life.
> >
> > However, in the case we're considering, the aux battery
> > may be replaced in an few years never having been deeply
> > discharged over the lifetime of its service. It's my
> > considered judgement that adding the extra gee-whiz
> > components for pampered recharge only adds to parts
> > count and pilot/maintenance workload and would contribute
> > no measurable increase in service life of the battery.
> >
> > *
> >
> > href="http://www.matronics.com/Navigator?AeroElectric-List">http://www.matronics.com/Navigator?AeroElectric-List
> > href="http://forums.matronics.com">http://forums.matronics.com
> > href="http://www.matronics.com/contribution">http://www.matronics.com/c*
> >
> > *
>
> href="http://www.matronics.com/Navigator?AeroElectric-List">http://www.matronics.com/Navigator?AeroElectric-List
> href="http://forums.matronics.com">http://forums.matronics.com
> href="http://www.matronics.com/contribution">http://www.matronics.com/c*
>
> *
>
>
> *
>
>
Message 8
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|
I've just started to build an X-Air H with a Jabiru 2200A on the front and am looking
at adapting Z-20 for my VFR needs. This is the first time both building
a plane and getting this far into ANY electronics for me, so apologies up front
for dumb questions.
1. If my battery (RG) is on the firewall, a) would this change anything in the
standard design and b) what would I be safe installing engine side of the firewall?
2) Having flown spam cans most of my flying career, is it really OK without an
Avionics master? I've read the theory, but all of the bits haven't formed a neat
line in my head yet!
3) I'm putting together a Bill of Materials for this design - has anyone done this
already?
4) Has anyone amended/added to Z-20 in the light of experience?
Thanks in advance.
Ian Wilson
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=156349#156349
Message 9
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Subject: | switch rating question |
Bob, in your document, you state:
"...For regulators that use the
field supply line to also sense bus voltage, I'll routinely use
20AWG wire in a 3 amp circuit! This is a voltage drop
consideration. Some regulators become unstable with mere
millivolts of uncertainty about bus voltage. A 22AWG field
supply, 5 feet long inserts 240 millivolts of "rubber band" in
the regulator's sense circuit with a 3 amp load. Dropping to
20AWG drops the uncertainty to 150 millivolts."
I experienced this problem in my RV-9A using 20 AWG wiring. It seems that
the sum of all of the voltage drops through wire, connections, contactor,
master bus, breaker and switch was enough to excite instability in my
voltage regulator. This lead to pulsating alternator output and
over-voltage alarms. Replacing a defective master switch helped with the
overvoltage, but the pulsating voltage was still apparent.
I fixed it by adding the circuit shown on the link below. It involved
adding some 16AWG wiring an automotive relay, a couple of diodes and a
fusible link. All of the wiring was firewall-forward, so it's pretty
stratightforward. The overvoltage crowbar still works with this circuit,
turning off the relay. I've added secondary overvoltage protection in case,
for some reason, the relay sticks shut during an overvoltage event that
triggers the crowbar.
Now I get rock-steady voltage regulation.
Vern Little RV-9A.
http://www3.telus.net/aviation/flying/RV-9A/Tips.html
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: January 5, 2008 8:36 AM
Subject: Re: AeroElectric-List: switch rating question
--> <nuckolls.bob@cox.net>
At 01:48 AM 1/5/2008 -0500, you wrote:
><mike109g6@insideconnect.net>
>
>Bob,
>Just a general question for you about the correct gauge wire to use on
>lights, ie taxi/landing. Math/index chart states 14awg for 100w halogen,
>but Van's lights, Duckwork is the brand I think, states in their
>instructions 18awg for 55w or 16awg for 100w halogens. Since Van's sells
>them for their planes, why the difference in suggested awg? Is this
>simply a difference in a perfect world theory' or 'what works in the real
>world'? Your input would be appreciated.
See:
http://www.aeroelectric.com/articles/wiresize.pdf
Bob . . .
Message 10
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Subject: | Re: Exploding Capacitors? |
Thanks Bob for the reply. I figured the capacitors on the pumps were not necessary
and therefore wired them up last night without them. I do that the capacitor
on the alternator wired per your instructions in the Aeroelectric book.
Thanks again for the response.
--------
Darin Hawkes
Series 7 (under Construction)
914 Turbo
Ogden, Utah
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=156406#156406
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Subject: | Re: 14 v Gyro on a 12 volt sustem? |
Gilles,
Thx pard, You are reading me right. I thought it surely should work ok, but thought
I oughtta ask around, since the investment in an Electric Artifical horizon
is pretty substantial.
Bob,
Thx also, but I think the any aircraft with a Rotax 912 for power is classified
as a 12 volt system not 14..(I think). My confusion has arrived when looking
at all the Attitude Gyros out there, they are listed by voltage in several different
ways. Some say 10 to 32v...some say 14...some say 24 or 28V..and on none
of the manufacturers website could I find anything listed about minimum voltage,
other than some will show the flag when volts get to low...but none say HOW
low...
I just love these forums,,for they bring fellas with practical experience together
with fellas who have not been down a particular road yet, and all so very
easily.
Smooth air and blue skies to you all!
--------
Don G.
Central Illinois
Kitfox IV Speedster
Luscombe 8A
http://www.geocities.com/dagger369th/my_firefly.htm
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=156414#156414
Message 12
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Subject: | Electrical System Reliability (and other ???) |
Hi Bob:
I'm in the beginning phase of designing my electrical system. The
following are the particulars of my setup:
Aircraft Mission - IFR (IMC is a likelihood), night and remote
backcountry operations.
Engine - Lycoming IO-540.
Glass Panel - One Dynon D180 EFIS/EMS and one Dynon D120 EFIS
both with internal battery backup. They are supposed to be able
to cross-display via Dynon's D-SAB.
Avionics - Garmin GMA-340 Audio, SL30 Nav/Com, SL40 Com, GTX 327
Transponder, GPS 496, Dynon AOA/Heated pitot tube. All of
the avionics were pre-wired by Approach/FastStack using their connecting
hub. The GPS 496 has internal batteries as well as an
external power source. I also have a ICOM IC-A23 handheld Com/VOR that
I always carry with me.
Electronic Ignition - LASAR controller with dual Slick mags.
One mag is equiped with a sensor for the LASAR system and
the other is impulse coupled. Both are inop while the electronic system
is operating. The system has the "Bush Kit" which
is supposed to default to operating on the mags alone in the event of
electrical or software failure. The controller is supposed
to operate with voltages down to 5.5volts.
Vacuum System - None
Alternator/Regulator - B&C L-60 Alternator and B&C LR3C-14
Regulator.
Fuel Injection - Bendix style fuel injection with Airfllow
Performance auxiliary fuel pump.
Electrical Controls - Three axis RAC trim system, Electric
flaps, Electric cowl flaps.
Lighting - Dual Strobe lights, Nav Lights, Dual taxi lights,
Dual landing lights, Dual "Type C4A" military style cockpit lights.
Autopilot - TruTrak Digiflight II two-axis autopilot.
Battery(s) - My intent is to use the Odyssey series battery(s).
Before I go any further with the design I need to make the following
decisions:
1. Single or Dual Alternator. If dual alternator, size of second
alternator and type of second regulator.
2. Single or Dual Battery. If dual battery, isolated systems or
combined and capacity of each battery.
3. Glass Panel alone or Glass Panel with back-up "Steam Gauges",
Airspeed, Altimeter, Turn Coordinator, Compass.
I have read through Sections 2, 3 and 17 of your book several times as
well as the wiring diagrams and various articles on your site. These
offer a great amount of information and advice which I'm sure would
allow a knowledgeable person to make the proper decisions. However, my
knowledge, experience and confidence are limited so I would like to
confirm with you my interpretation of the information and get your
confirmation/critique thereof. Here goes:
The first is that designing for complete battery failure i.e. a
dead short that would take down the whole system in NOT
necessary. This seems to be covered well on page 17-11 in a
paragraph that contains the following, "Last, the antiquated
concerns for battery "failure"....RG battery reliability....drives the
probability of gross battery failure to zero." However, I would
like to confirm that the Odyssey batteries would fall under the same
class as "RG battery reliability" and that I would NOT need
to design for battery failure given my intended mission and battery
selection. Would you concur with that??
Regarding decision number #1: Your comments on several pages of
sec. 17 clearly indicate your preference for dual
alternators. My setup in heavily dependent on electrical systems for
normal operations. Based on that and on your
comments, I would opt for a second alternator using B&C SD-20 Alternator
and B&C SB1B-14 Standby Controller. Given the need of a second
alternator, the weight penalty between the 20amp and 8 amp models is 3
pounds. It would seem the 20amp would provide near
normal operations for as long as it works should the primary alternator
fail. Would you concur with that??
Regarding decision number #2: This has several sub-parts.
A - Your comments in sec. 17 seem to indicate that with a
dual alternator setup as I opted for in #1, dual batteries with
isolated systems are NOT necessary as a design point for
in-flight electrical failure. I would like to avoid the dual
battery contactors and the crossfeed contactor by using a
single battery source. Would you concur with that?? If it
makes a difference, the battery(s), regulators and LASAR
controller will be located on the cabin side of the firewall.
B - One of the mission requirements is backcountry
operations. Given that, one my design points was the ability to start
the plane with a completely dead primary (cranking) battery,
say as a result of leaving the master on. That is the reason I
opted for the LASAR system with the bush kit. However, given my
configuration I would need some sort of standby
electrical power. To that end I am considering two options:
Option 1: Design in a permanent Non-Cranking (Aux)
battery and bus as shown in fig. Z-35. to power the Fuel Pump,
LASAR system, and one EFIS/EMS.
Option 2: Design in an external power plug for the
fuel pump ONLY and carry a small battery with me during
backcountry operations ONLY. With my configuration I do
not need the EFIS/EMS or the LASAR system to
function to just start the engine. The only thing I really need is
a few seconds of fuel pump operation to pressurize the
system in order to hand prop the engine. If I was backcountry I would
have 12 volts of battery power someplace
anyway.
My choice would be for Option 2. Would you concur
with that???
C - Odyssey offers several batteries ranging in
capacity form 14 to 28AH, in cranking power from 535 to 925CCA
and in weight from 12.0 to 26.0 lbs. In the unlikely
event of the same flight failure of both alternator/regulator systems
opted for in #1, and according to the method used on
page 17-6, any of the batteries would satisfy the requirements
of my E-bus. However, I am not so sure about starting power
for normal operations. My engine is fuel injected and
high compression. My space limitations would preclude me from
installing the 28AH/925CCA/26lb battery. That
would leave two preferred batteries; The PC545 (14AH/545CCA/12.6lbs) and
the PC680 (17AH/680CCA/15.4lbs). If necessary I
could install two of either the PC545 or PC680 batteries wired together
to act as one. My first preference would be a
single PC680, second would be two of the PC545's and lastly two of the
PC680's.
Here I would simply ask for your recommendation as
to which way to go??.
Regarding decision #3: Well this started out to be a long and
involved question but as I was typing out my reasoning and
explanation, I made the decision to opt for the back up gauges. I
intend to file IFR for trips and that means at some point I
will probably be in IMC and there is just no way that I am going into
IMC without them. Thanks for helping me get that one out of
the way. Its been bothering me for months.
There are a couple of other questions I have:
On page 17-10 you say, "When you trade generators for
alternators, loss of a battery contactor may well precipitate total loss
of electrical power. Alternators, don't run well without a battery".
Yet when I look at Figs 17-2,3,4,5,6, and 8, all of them place the Alt
field switches on the main bus with the contactor in the path to the
battery. If I understand your statement correctly, it seems that if you
loose a single contactor in any except fig 17-5 & 6, Dual Batteries, you
would lose all charging systems. Shouldn't there be a pathway to
energize the Alt fields thru the E bus in case of a contactor failure.
Is my reasoning correct?? It looks like Fig Z-13/20 does that for the
Aux Alt only and Fig Z-12 doesn't for either Alt. Is that correct??
Wouldn't you want to be able to energize both Alt systems from the
E-bus in case of contactor failure with a single battery??? Or
alternatively, what about two contactors for a single battery??? They're
cheap enough??? Would that work???
I really don't understand what P-leads are or the difference
between P-mags and E-mags. What do I have with the LASAR system??? I
looked but couldn't find any articles to explain mag operation or what
they are. Could you point be to the proper article???
Thanks a lot Bob.
Mark Richards
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Subject: | Re: Z-20 Adaptation |
At 09:09 AM 1/6/2008 -0800, you wrote:
>
>I've just started to build an X-Air H with a Jabiru 2200A on the front and
>am looking at adapting Z-20 for my VFR needs. This is the first time both
>building a plane and getting this far into ANY electronics for me, so
>apologies up front for dumb questions.
>
>1. If my battery (RG) is on the firewall, a) would this change anything in
>the standard design and b) what would I be safe installing engine side of
>the firewall?
Been there, done that. About half the FA fleet
has batteries forward of the firewall; they live
just fine up there.
>2) Having flown spam cans most of my flying career, is it really OK
>without an Avionics master? I've read the theory, but all of the bits
>haven't formed a neat line in my head yet!
If understanding the theory hasn't served you well
then all you have left is faith in a tradition
for which there is no demonstrable science.
I'd rather see you comfortable with your decision
than to adopt a practice that you cannot personally
trust. Put in the AV Master if it assuages any
concerns.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
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