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Battery Proximity and mounting
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flyboybob1(at)gmail.com
Guest

Posted: Fri Jun 26, 2009 11:14 am Post subject: Battery Proximity and mounting

Bob,



After reading your response to my wanting two batteries I again took a look

at my design.  To be more accurate, I have a hybrid version with Z-14 as the

power distribution section (alternator, dynamo, and batteries) and Z-13

implimentation of the main and essential buses.  The main bus is on the

battery bus supported by the 40A alternator and and the essential bus is

supported by your recomended Shack bridge rectifier fed from both battery

buses.  There is also a backup essential bus power switch from the second

batery bus.



My reason for redundant power distribution is that there can be some

unforseen failure modes (vibration, fatigue, materiel defect, or assembly

error) that would percipitate sweat on my part with hours of fuel in the

tank no fuel being pumped to the engine or spark in the ignition.



There have been a couple of pilots responding to this thread indicating that

they have flown successfully for hundreds of hours on the primary system and

subsequently decided that the second battery is not needed.  In hind sight I

could agree with them on Z13/20.  For now I'll carry the extra insurance as

it doesn't add much weight or complexity and it gets the best parts of both

designs as it applies to my design goals.



Regards,

Bob Lee

N52BL  KR2

Suwanee, GA  USA

92% done only 67% to go!

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Jun 26, 2009 11:32 am Post subject: Battery Proximity and mounting

At 12:46 PM 6/26/2009, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: <Flagstone(at)cox.net>



 Bob:



 A complete non answer.  Lot of words...no relevance.



 On page 17-11 (rev11) you state that "RG battery reliability and performance supplemented with good preventative maintenance drives probability of gross battery failure to zero"



 You don't say "near zero", "close to zero", "approaching zero", or any such thing.  To claim anything has a zero probability of failure is a pretty bold statement to make.  Further,  judging from the general tone of your writing style, there's as much a chance of  that statement being rhetoric as anything else. 	


    Gross battery failures are functions of two things.

    Design or manufacturing defect -OR- abuse of the battery

    that places stresses on it that are outside design limits.

    Modern RG batteries are assembled on highly mechanized

    processes and demonstrate thousands to millions of units

    of field service history per year. Very few instances of

    design or manufacturing defect go un-corrected. This

    leaves abuse which cannot be predicted or quantified.

    

    I'll go fix that statement to read "very close to zero".



 

  	  Quote: 	
		  When I first read your book a couple years ago,  I tried to get some clarification from you on that statement.  At first, when I asked directly, you simply didn't address the question.  I gave up on that approach.   Since then, whenever other group members have touched on the issue, I have attempted, by asking questions in different ways, to get  you to explain further the meaning of your statement.  In response to the inquiries (mine and others) on this subject, you either:

    1.  Don't answer.

    2.  Provide theoretical fluffery

    3.  Answer questions that aren't asked

    4.  Introduce extraneous issues

    5.  Claim its beyond understanding



 At first, I thought I was close to getting some answers this time, but as before, the answers degraded into one or more of the above categories.  I really don't understand why you can't give a full and complete explanation of what you mean by "gross battery failure" and "zero probability" in some meaningful and understandable way.  After all, its your statement, you should be able to substantiate it.  But, that's apparently not the case. I've noticed that you seem to follow that pattern on a few other issues as well.   Anyway, I'm tired of  trying to coax an explanation out of you so I won't bring up it up again.  I'll just assume the statement was the result of your writing style and not to be taken literally.  In any regard,  I don't need the information now, and when I do,  I'll get it from other sources. 	




 

    You wrote:



 "I intend to use to use two batteries for the maintenance benefits you outline in your book and for the additional cranking power."



    I recommended that you explore the need/value for "more

    cranking power" with a follow-up that many, many airplanes

    are flying with single 17 a.h. batteries and enjoy satisfactory

    cranking performance. You also said:



 "Right now I'm just trying to get a clear understanding of the RG battery's reliability and performance limitations."



    To the second statement it was my intention to suggest that

    battery "reliability" given in terms of failures per flight

    hour is not possible. Nobody has done the studies nor have

    the candidate manufacturers implemented statistical process

    controls intended to sustain advertised reliability numbers. 

    It was not my intent to be mysterious or condescending. I'm

    only saying that credible "reliability" numbers don't exist.



    But assuming they did. Let us hypothesize that a flooded

    24 a.h. Rebatt has a 453 failures per million flight hours

    and a 24 a.h. Odyssey was 305 failures per million flight

    hours . . . how would you use that data? Suppose I said

    that you have a 1 in 103 probability of ending a flight

    due to a battery failure? Of what use is that number? And

    how many mud-throwing fights can we start by debating how

    that number was calculated?



    First we need to define and separate "failure" from "end-of-

    life." The vast majority of batteries in ALL vehicles are

    replaced because they are at end-of-life as demonstrated

    by a failure to crank the engine. Would you call that a

    "failure" in aircraft system reliability parlance?

    In aircraft parlance, a battery that fails to crank

    an engine is probably months past end-of-life established

    by battery-only endurance design goals.



    Consider this same conversation going on about tires.

    How could anyone make recommendations for reliability

    of any particular tire without defining weight

    of aircraft, pilot skills, runway surfaces, landing

    speeds, etc. etc.



    A crummy tire can last a long time under the right

    circumstances . . . a top-of-the-line tire can

    be abused and used up with some dispatch.



    What do you wish I would have told you? Are you looking

    for brand recommendations. Service recommendations?

    Charging recommendations? ALL of the above can have a

    profound effect on service life of ANY battery. I can

    only suggest the universal recipe for success calls

    for  . . .

   

        Monitoring the performance of any brand or style of 

        battery and replacing it when it falls below some

        standard of performance THAT YOU ADOPT. Replacement

        is based on failure to store and deliver energy

        needed for YOUR battery only endurance mode.



    This is what we do in biz-jets. None of those

    batteries have published reliability numbers. In the

    fleet, a few folks get 3-4 years of service.

    A few folks get less than 2 years. Most fall

    someplace in between. An exceedingly small number

    of the total experience unanticipated gross failure.

    How would you have me describe "reliability" of those

    batteries?



    For me to offer reliability opinions without also

    stating design, operating and maintenance goals for

    the battery would be without foundation.



    I'm sorry about your disappointment but I hope it's

    clear that your question cannot be simply answered.

    If you discover "another source" that offers

    satisfying answers, please share that information

    with us. 

    

    Bob . . .

  

     [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Jun 26, 2009 1:38 pm Post subject: Battery Proximity and mounting

At 02:01 PM 6/26/2009, you wrote:

 	  Quote: 	
		  



Bob,



After reading your response to my wanting two batteries I again took a look

at my design.  To be more accurate, I have a hybrid version with Z-14 as the

power distribution section (alternator, dynamo, and batteries) and Z-13

implimentation of the main and essential buses.  The main bus is on the

battery bus supported by the 40A alternator and and the essential bus is

supported by your recomended Shack bridge rectifier fed from both battery

buses.  There is also a backup essential bus power switch from the second

batery bus.


	


    Okay. The term "hybrid" raise questions. The Z-figures

    are stand-alone, recipes for success that have passed

    muster for some analysis of failure modes and matched

    to missions. Mixing/matching between Z-figures should

    be evaluated for new failure modes. Can you sketch your

    power distribution and scan it for sharing with he group?

 	  Quote: 	
		  My reason for redundant power distribution is that there can be some

unforseen failure modes (vibration, fatigue, materiel defect, or assembly

error) that would percipitate sweat on my part with hours of fuel in the

tank no fuel being pumped to the engine or spark in the ignition.


	


    My sense is that your failure analysis may have been

    too broad with respect to kinds and numbers of

    failures. Many of my readers have stacked multiple

    failures onto a single flight cycle. This is so

    rare that part 23 aircraft don't even consider

    multiple failures for certification, part 25 airplanes

    consider it and ask the builder to show better one in

    ten to the minus 6 probability in a single system.

    But the neat thing is that completely independent

    systems need not be nearly so failure resistant because

    their failures do not "stack". You only need to show

    a 1 x 10^-6 probability for failure in any single

    flight cycle. MUCH easier.



 	  Quote: 	
		  There have been a couple of pilots responding to this thread indicating that

they have flown successfully for hundreds of hours on the primary system and

subsequently decided that the second battery is not needed.  In hind sight I

could agree with them on Z13/20.  For now I'll carry the extra insurance as

it doesn't add much weight or complexity and it gets the best parts of both

designs as it applies to my design goals.


	


    Have you done a load analysis on minimum

    energy requirements for sustained flight? Exactly

    how many watt-seconds of energy per flight hour are

    needed to run your engine? What engine are you

    using? Let's look at your hybridization and

    ponder the effects.

        Bob . . .



         ---------------------------------------

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

         ---------------------------------------

flyboybob1(at)gmail.com
Guest

Posted: Fri Jun 26, 2009 2:52 pm Post subject: Battery Proximity and mounting

Lectric Bob asked:



    Have you done a load analysis on minimum

    energy requirements for sustained flight? Exactly

    how many watt-seconds of energy per flight hour are

    needed to run your engine?



Don't have watt-seconds/flight-hour but there is a spread sheet with amps

required in various flight modes.  Here's a link to my electrical system

design documentation.



http://kr.flyboybob.com/web_pages/kr2/electrical%20and%20instrument/electric

al.htm



At the bottom of the page there are links to the wiring diagrams.



Regards,

Bob Lee

N52BL  KR2

Suwanee, GA  USA

92% done only 67% to go!

Speedy11(at)aol.com
Guest

Posted: Sat Jun 27, 2009 5:24 am Post subject: Battery Proximity and mounting

Looks like we have another a**hole that refuses to include his  name.  Could he be ashamed of it?

 I got a nasty note from him off the forum for my comments on the  forum.

 Wonder what up with him?

 Stan Sutterfield

 Do not archive

  

  	  Quote: 	
		  Bob:



A complete non answer.  Lot of words...no    relevance.



On page 17-11 (rev11) you state that "RG battery reliability    and performance 

supplemented with good preventative maintenance drives    probability of gross 

battery failure to zero"



You don't say "near    zero", "close to zero", "approaching zero", or any such 

thing.  To    claim anything has a zero probability of failure is a pretty bold    

statement to make.  Further,  judging from the general tone of    your writing 

style, there's as much a chance of  that statement being    rhetoric as 

anything else.



When I first read your book a couple    years ago,  I tried to get some 

clarification from you on that    statement.  At first, when I asked directly, 

you simply didn't    address the question.  I gave up on that approach.   Since    

then, whenever other group members have touched on the issue, I have    

attempted, by asking questions in different ways, to get  you to    explain 

further the meaning of your statement.  In response to the    inquiries (mine 

and others) on this subject, you either:

       1.  Don't answer.

    2.  Provide theoretical    fluffery

    3.  Answer questions that aren't    asked

    4.  Introduce extraneous issues

       5.  Claim its beyond understanding



At first, I thought I was close    to getting some answers this time, but as 

before, the answers degraded    into one or more of the above categories.  I 

really don't understand    why you can't give a full and complete explanation 

of what you mean by    "gross battery failure" and "zero probability" in some 

meaningful and    understandable way.  After all, its your statement, you 

should be    able to substantiate it.  But, that's apparently not the case. 

I've    noticed that you seem to follow that pattern on a few other issues as    

well.   Anyway, I'm tired of  trying to coax an explanation    out of you so I 

won't bring up it up again.  I'll just assume the    statement was the result 

of your writing style and not to be taken    literally.  In any regard,  I 

don't need the information now,    and when I do,  I'll get it from other    

sources.

Thanks 	


 

  

 Make your summer sizzle with fast and easy recipes for the grill.

  [quote][b]

Michael Wynn

Joined: 10 Jan 2006
Posts: 148
Location: San Ramon, CA

Posted: Sat Jun 27, 2009 6:51 am Post subject: Battery Proximity and mounting

Hi all,

  

 This has been a very enlightening thread for me.  I am persuaded that  a single battery, dual alternator is probably quite sufficient for my mission  envelope and will save me a good #20 over using the second battery.

  

 This is not the forum to argue the battery position in an RV 8.  There  are several long discussions on the VAF forum.  The up side of the rear  position is the weight and balance advantage, as RV 8's tend to be nose  heavy.  The down side is an additional six to eight foot run of #2 welding  cable, its associated weight, resistance and potential for chaffing.  I  will have to give that a little more thought.

  

 Thank you all for your insights and off-line diagrams.

  

 Regards,

  

 Michael Wynn

 RV 8 FWF

 San Ramon, CA

  

  

 An Excellent Credit Score is786/aol?redir=http://www.freecreditreport.com/pm/default.aspx?sc=668072%26hmpgID=62%26bcd=JuneExcfooterNO62>See Yours in Just 2 Easy Steps!

  [quote][b]

_________________
Michael Wynn
RV 8
San Ramon, CA

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Jun 27, 2009 7:16 am Post subject: Battery Proximity and mounting

At 08:18 AM 6/27/2009, you wrote:

  	  Quote: 	
		   Looks like we have another a**hole that refuses to include his name.  Could he be ashamed of it?

 I got a nasty note from him off the forum for my comments on the forum.

 Wonder what up with him? 	


   Gently my friend. This is after all a classroom

   with a broad spectrum of attendee needs and

   skill sets. The value of what we do here is

   not increased by prejudicial words. Let

   us strive to be teachers with a goal of

   working to everyone's satisfaction.

   



 

        Bob . . .



         ---------------------------------------

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

         ---------------------------------------



     [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Jun 27, 2009 7:57 am Post subject: Battery Proximity and mounting

At 09:49 AM 6/27/2009, you wrote:

  	  Quote: 	
		   Hi all,

  

 This has been a very enlightening thread for me.  I am persuaded that a single battery, dual alternator is probably quite sufficient for my mission envelope and will save me a good #20 over using the second battery.

  

 This is not the forum to argue the battery position in an RV 8.  There are several long discussions on the VAF forum.  The up side of the rear position is the weight and balance advantage, as RV 8's tend to be nose heavy.  The down side is an additional six to eight foot run of #2 welding cable, its associated weight, resistance and potential for chaffing.  I will have to give that a little more thought.

  

 Thank you all for your insights and off-line diagrams. 	


   Batteries have been the classical mitigator

   of wight and balance issues since day-one.

   Of all major weight contributors, the batteries

   have always been the easiest to relocate.

   I'll suggest that concerns for wire weight

   and installation requirements take a very

   distant back seat to the airplane's handling

   qualities. Batteries have been carried

   around in the tail of airplanes in tens of

   thousands of airplanes. When I started at

   Cessna, I think all of our batteries were in

   the tail. Doing a good job of installing

   the wire is a trivial task.



 

        Bob . . .



         ---------------------------------------

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

         ---------------------------------------



     [quote][b]

Flagstone(at)cox.net
Guest

Posted: Sat Jun 27, 2009 11:08 pm Post subject: Battery Proximity and mounting

To All:

  

 I recently made statements in a post  under this subject that was critical of Bob's responsiveness to an issue.   The statements were based on my recollections of posts over the past  two years.  Bob was kind enought to continue the discussion with me  off-group.  In preparation for that discussion, I reveiwed my posts on the  issue and could not find support for the statements I made.  I would like  to retract those statements and make an appology to Bob and the group for making  them.

  

 Mark

   [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Jun 28, 2009 7:35 am Post subject: Battery Proximity and mounting

At 02:03 AM 6/28/2009, you wrote:

  	  Quote: 	
		   To All:

  

 I recently made statements in a post under this subject that was critical of Bob's responsiveness to an issue.  The statements were based on my recollections of posts over the past two years.  Bob was kind enought to continue the discussion with me off-group.  In preparation for that discussion, I reveiwed my posts on the issue and could not find support for the statements I made.  I would like to retract those statements and make an appology to Bob and the group for making them.

  

 Mark 	


   Thank you sir. No problem . . . and let's not

   dwell on it. We are all friends here.



 

        Bob . . .



         ---------------------------------------

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

         ---------------------------------------    [quote][b]

Speedy11(at)aol.com
Guest

Posted: Sun Jun 28, 2009 9:20 am Post subject: Battery Proximity and mounting

Ha - I thought I was being gentle.

 My apology.

 Actually, I got an off forum email from him (his name is Mark) and we  apologized to one another.

 Stan

  

  	  Quote: 	
		  >Looks like we have another a**hole that refuses to include his    

 	  Quote: 	
		  name.  Could he be ashamed of it?

I got a nasty note from    him off the forum for my comments on the forum.

Wonder what up with    him?


	


   Gently my friend. This is after all a    classroom

   with a broad spectrum of attendee needs    and

   skill sets. The value of what we do here    is

   not increased by prejudicial words. Let

   us    strive to be teachers with a goal of

   working to everyone's    satisfaction.

        Bob . .  .

	


 

  

 Make your summer sizzle with fast and easy recipes for the grill.

  [quote][b]

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