Matronics Email Lists :: View topic - Brownout Battery System P.S.

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Brownout Battery System P.S.

Matronics Email Lists Forum Index -> AeroElectric-List

View previous topic :: View next topic

Author Message

nuckolls.bob(at)cox.net
Guest

Posted: Tue Apr 22, 2008 5:59 am Post subject: Brownout Battery System P.S.

I've been pondering this discussion for the last day or so and

   I wasn't pleased with the lack of elegance. It seemed that your

   design goals were not well served with the present suite of hardware

   (too heavy).



   An FMEA study of Z-13/8 yields and excellent reliability scenario

   but it cannot address the fact that some modern EFIS products are

   unable to deal with the real world of millisecond long, bus brownout

   during starter-inrush loads. See:



http://www.aeroelectric.com/Pictures/Curves/99_Saturn_SL1.jpg



   Indeed, no single-battery systems is designed to provide

   a constant source of power that stays inside the operating

   envelope of these computer based products.



   One obvious solution is a second battery. The question is

   how big? It only needs to supply power to a limited suite of

   ship's hardware for a few tens of milliseconds while the starter

   motor spins up at the onset of each cranking cycle. In terms

   of ENERGY, the requirements are trivial. So the real sizing

   considerations are for internal impedance of the battery. Ideally,

   we'd like to put an array of AA NiMh cells in to support the e-bus

   during brownout . . . but these cells have finicky charging

   requirements. It's not that they wouldn't do the job . . . but

   system design issues are more complex and parts count goes

   up.



   So what's a reasonable middle ground? Take a peek at:

   Take a peek at this drawing I did last night:



http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z13-8A(BrownOutBattery).pdf



   Here I've suggested that you dump the #2 fat battery and

   the fat contactors associated with #2 master and crossfeed.

   Install a much smaller (7.2 AH, 5.5# 0.04 ohm) "brownout

   battery" and a pair of cube power relays wired such that

   the e-bus is supported ONLY by the brownout battery during

   engine cranking and only while the main bus is loaded so

   heavily that it cannot keep the EFIS from resetting.



   This same technique could be added to any single battery

   system (or even Z-14 where you wanted to use both batteries

   for cranking). This modification to Z-13 does not burden the

   SD-8 with supporting fat contactors that are never expected

   to carry cranking currents . . . hence may be ably replaced

   with smaller, plastic relays.



   P.S. Here's an exemplar battery that seems well suited to

   this task:



http://aeroelectric.com/Mfgr_Data/Batteries/Panasonic/LC-R127R2P.pdf



   Bob . . .

Bret Smith

Joined: 09 Jan 2006
Posts: 178
Location: Mineral Bluff, GA

Posted: Tue Apr 22, 2008 6:50 am Post subject: Brownout Battery System P.S.

Bob, this is similar to our design I showed you when you were in Atlanta...

http://www.flightinnovations.com/images/wiring/Main%20Power%20Distribution%20010308.JPG



Bret Smith

RV-9A "Canopy"

Blue Ridge, GA

www.FlightInnovations.com

---

_________________
Bret Smith
RV-9A (Emp)

nuckolls.bob(at)cox.net
Guest

Posted: Tue Apr 22, 2008 7:58 am Post subject: Brownout Battery System P.S.

At 10:41 AM 4/22/2008 -0400, you wrote:



 	  Quote: 	
		  



Bob, this is similar to our design I showed you when you were in Atlanta...

http://www.flightinnovations.com/images/wiring/Main%20Power%20Distribution%20010308.JPG


	


   Yeah . . . but the only time the brownout battery gets

   properly attached to the system for charge maintenance is

   when the e-bus alternate feed switch is closed.



   The architecture I posted keeps the brownout battery

   connected across the main battery at all times except while

   cranking the engine. Zero demands on pilot for proper

   orientation of switches.



   Bob . . .

grjtucson

Joined: 07 Apr 2008
Posts: 7
Location: Tucson, AZ

Posted: Tue Apr 22, 2008 8:14 am Post subject: Re: Brownout Battery System P.S.

 	  nuckolls.bob(at)cox.net wrote: 	
		  At 10:41 AM 4/22/2008 -0400, you wrote:



   Yeah . . . but the only time the brownout battery gets

   properly attached to the system for charge maintenance is

   when the e-bus alternate feed switch is closed.



   The architecture I posted keeps the brownout battery

   connected across the main battery at all times except while

   cranking the engine. Zero demands on pilot for proper

   orientation of switches.



   Bob . . . 	




Bob,



I like the new drawing but help me out in understanding how the E-Bus alternate feed relay gets energized and thus energizes the e-bus in the event the master switch is open. If I don't have power to the main bus, there is no power to the e-bus unless the alt. feed relay is closed, but the only way for the alt. feed relay to close is for there to be power to the e-bus.



Shouldn't the alt. feed relay magnet positive terminal come from the BATTERY bus and then go to the switched ground, or be switched power to that positive terminal and then go to ground?



Unless I am totally missing something...



George

Tucson, AZ

RV-7

_________________
George Jenson - http://www.georgejenson.com
Tucson, AZ - RV-7 Standard Build
Empennage Completed 1/06
Wings Completed 11/06
Fuselage in Progress

rshannon

Joined: 05 Sep 2007
Posts: 62

Posted: Tue Apr 22, 2008 8:35 am Post subject: Brownout Battery System P.S.

On Tue, Apr 22, 2008 at 6:54 AM, Robert L. Nuckolls, III <nuckolls.bob(at)cox.net (nuckolls.bob(at)cox.net)> wrote:

 	  Quote: 	
		   .. 

   Take a peek at this drawing I did last night:

 

 http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z13-8A(BrownOutBattery).pdf

 

   Here I've suggested that you dump the #2 fat battery and

   the fat contactors associated with #2 master and crossfeed.

   Install a much smaller (7.2 AH, 5.5# 0.04 ohm) "brownout

   battery" and a pair of cube power relays wired such that

   the e-bus is supported ONLY by the brownout battery during

   engine cranking and only while the main bus is loaded so

   heavily that it cannot keep the EFIS from resetting.

 

   This same technique could be added to any single battery

   system (or even Z-14 where you wanted to use both batteries

   for cranking). This modification to Z-13 does not burden the

   SD-8 with supporting fat contactors that are never expected

   to carry cranking currents . . . hence may be ably replaced

   with smaller, plastic relays.

 

   P.S. Here's an exemplar battery that seems well suited to

   this task:

 

 http://aeroelectric.com/Mfgr_Data/Batteries/Panasonic/LC-R127R2P.pdf

 	


Bob,



I like the idea of using the starter switch to trigger brown out protection.



Although my AFS EFIS's aren't subject to the dropout (they will go to their internal backup battery automagically if needed) I'm thinking of using the AUX battery mgmt. module scheme, which includes manual switching to bring the AUX battery back online to extend E-bus life. Presumably, it won't be hard to parallel the starter switch with the AUX battery mgmt. manual switch to combine the functionality.

 

Also, FWIW, B&C has a similar battery (BC102-1) that is listed as 0.45 pounds lighter than the Panasonic.



Ron



  [quote][b]

nuckolls.bob(at)cox.net
Guest

Posted: Tue Apr 22, 2008 8:48 am Post subject: Brownout Battery System P.S.

 	  Quote: 	
		  

Bob,



I like the new drawing but help me out in understanding how the E-Bus 

alternate feed relay gets energized and thus energizes the e-bus in the 

event the master switch is open.



If I don't have power to the main bus, there is no power to the e-bus 

unless the alt. feed relay is closed, but the only way for the alt. feed 

relay to close is for there to be power to the e-bus.



Shouldn't the alt. feed relay magnet positive terminal come from the 

BATTERY bus and then go to the switched ground, or be switched power to 

that positive terminal and then go to ground.



Unless I am totally missing something...


	


   Good eye! Thank you. I've published revision B

   to correct the error at:



http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z13-8B(BrownOutBattery).pdf



   Bob . . .

nuckolls.bob(at)cox.net
Guest

Posted: Tue Apr 22, 2008 10:35 am Post subject: Brownout Battery System P.S.

At 09:30 AM 4/22/2008 -0700, you wrote:



 	  Quote: 	
		  On Tue, Apr 22, 2008 at 6:54 AM, Robert L. Nuckolls, III 

<<mailto:nuckolls.bob(at)cox.net>nuckolls.bob(at)cox.net> wrote:

>...

>

>  Take a peek at this drawing I did last night:

>

><http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z13-8A%28BrownOutBattery%29.pdf>http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z13-8A(BrownOutBattery).pdf

>

>  Here I've suggested that you dump the #2 fat battery and

>  the fat contactors associated with #2 master and crossfeed.

>  Install a much smaller (7.2 AH, 5.5# 0.04 ohm) "brownout

>  battery" and a pair of cube power relays wired such that

>  the e-bus is supported ONLY by the brownout battery during

>  engine cranking and only while the main bus is loaded so

>  heavily that it cannot keep the EFIS from resetting.

>

>  This same technique could be added to any single battery

>  system (or even Z-14 where you wanted to use both batteries

>  for cranking). This modification to Z-13 does not burden the

>  SD-8 with supporting fat contactors that are never expected

>  to carry cranking currents . . . hence may be ably replaced

>  with smaller, plastic relays.

>

>  P.S. Here's an exemplar battery that seems well suited to

>  this task:

>

><http://aeroelectric.com/Mfgr_Data/Batteries/Panasonic/LC-R127R2P.pdf>http://aeroelectric.com/Mfgr_Data/Batteries/Panasonic/LC-R127R2P.pdf



Bob,



I like the idea of using the starter switch to trigger brown out protection.



Although my AFS EFIS's aren't subject to the dropout (they will go to 

their internal backup battery automagically if needed) I'm thinking of 

using the AUX battery mgmt. module scheme, which includes manual switching 

to bring the AUX battery back online to extend E-bus life. Presumably, it 

won't be hard to parallel the starter switch with the AUX battery mgmt. 

manual switch to combine the functionality.


	


   ? if your EFIS is already brown-out proof, what's the

   task for an aux battery?

 	  Quote: 	
		  Also, FWIW, B&C has a similar battery (BC102-1) that is listed as 0.45 

pounds lighter than the Panasonic.


	


   Yeah, there's a bunch of possibilities. I'm still pondering

   a DIY project or perhaps a product for incorporation of some

   small capacity (read light weight) energy storage devices

   into an automatically managed brown-out battery assembly.



   Bob . . .

rshannon

Joined: 05 Sep 2007
Posts: 62

Posted: Tue Apr 22, 2008 12:10 pm Post subject: Brownout Battery System P.S.

 	  Quote: 	
		  

   ? if your EFIS is already brown-out proof, what's the

   task for an aux battery? 	


If I do add an AUX battery, it would be for extended E-bus run time.  I wouldn't add AUX battery weight for brown out protection alone, unless there was something else....

 

Wait! It would also keep my IIRG (Intergalactic Ionic Ray Gun) from rebooting! Perfect!  



Ron



  [quote][b]

nuckolls.bob(at)cox.net
Guest

Posted: Tue Apr 22, 2008 7:17 pm Post subject: Brownout Battery System P.S.

At 01:06 PM 4/22/2008 -0700, you wrote:

 	  Quote: 	
		  >  ? if your EFIS is already brown-out proof, what's the

>  task for an aux battery?



If I do add an AUX battery, it would be for extended E-bus run time.  I 

wouldn't add AUX battery weight for brown out protection alone, unless 

there was something else....



Wait! It would also keep my IIRG (Intergalactic Ionic Ray Gun) from 

rebooting! Perfect!  


	


   If you have an SD-8 in addition to the ship's main alternator,

   then you essentially enjoy unlimited e-bus endurance irrespective

   of the capacity of the ship's battery.



   Z-13 lets you run a battery until it doesn't crank the engine

   any more. Battery only endurance is not part of the "plan-B".



   Bob . . .

        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

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

rshannon

Joined: 05 Sep 2007
Posts: 62

Posted: Tue Apr 22, 2008 8:12 pm Post subject: Brownout Battery System P.S.

 	  Quote: 	
		   If you have an SD-8 in addition to the ship's main alternator,

    then you essentially enjoy unlimited e-bus endurance irrespective

   of the capacity of the ship's battery.

 

   Z-13 lets you run a battery until it doesn't crank the engine

   any more. Battery only endurance is not part of the "plan-B".

 

   Bob . . .

 	




Understood. Per other thread, I do have an SD-20S for backup ALT, so the plan C,D,E... AUX battery addition here is not compelling, as you suggest.



However, if I do have to go to the E-bus, perhaps due to a stuck starter, requiring shutdown of the main contactor even with an alternator still available, then battery endurance may be an issue, even if not a worry. Other than that, I might want independent capacity for ground ops (light, audio, radios, gizmos...) in the boonies with this mini bush plane. Those are probably the only things that would lead me to commit 6 lbs. (+/-) to an AUX battery system.

 

Ron

  [quote][b]

nuckolls.bob(at)cox.net
Guest

Posted: Wed Apr 23, 2008 5:43 am Post subject: Brownout Battery System P.S.

At 09:02 PM 4/22/2008 -0700, you wrote:

 	  Quote: 	
		  >  If you have an SD-8 in addition to the ship's main alternator,

>  then you essentially enjoy unlimited e-bus endurance irrespective

>  of the capacity of the ship's battery.

>

>  Z-13 lets you run a battery until it doesn't crank the engine

>  any more. Battery only endurance is not part of the "plan-B".

>

>  Bob . . .

Understood. Per other thread, I do have an SD-20S for backup ALT, so the 

plan C,D,E... AUX battery addition here is not compelling, as you suggest.

However, if I do have to go to the E-bus, perhaps due to a stuck starter,

    ??? how do you get a stuck starter contactor in flight?

 	  Quote: 	
		    . . .requiring shutdown of the main contactor even with an alternator 

 still available, then battery endurance may be an issue, even if not a 

 worry. Other than that, I might want independent capacity for ground ops 

 (light, audio, radios, gizmos...) in the boonies with this mini bush 

 plane. Those are probably the only things that would lead me to commit 6 

 lbs. (+/-) to an AUX battery system.

    Agreed.

    Bob . . .

Thomas.N.Gautier(at)jpl.n
Guest

Posted: Wed Apr 23, 2008 9:27 am Post subject: Brownout Battery System P.S.

Bob,



      I looked at your Z13-8B(BrownOutBattery).pdf. It seems to me

that the only reason not to hook a battery like the Panasonic LC-R127R2P

directly to the endurance bus and do away with the brown-out

battery relay, alternate feed relay and the E-bus alternate feed switch

is that the battery won't charge properly through the diode

connecting the main bus to the endurance bus. However, what if you use

a shottky diode for the main bus/endurance bus connection?



    The power shottky on the Perihelion Design site apparently has about

0.2v forward drop. The Panasonic spec sheet you pointed to says, if I

read it right, that the battery needs 13.6-13.8 v terminal voltage to trickle

charge. So the brown-out battery should stay charged OK if the alternator

is regulated to supply more than 14.0 v, which I understand it has to do to

keep the main battery charged.



     Am I missing something simple (or subtle) that makes this not work or

a bad idea?



Nick Gautier

RV-10, in progress



At 06:59:06 AM PST US 4/22/2008 you wrote:



 	  Quote: 	
		    I've been pondering this discussion for the last day or so and

  I wasn't pleased with the lack of elegance. It seemed that your

  design goals were not well served with the present suite of hardware

  (too heavy).

    ~snip~
	


 	  Quote: 	
		     So what's a reasonable middle ground? Take a peek at:



  Take a peek at this drawing I did last night:

http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z13-8A(BrownOutBattery).pdf


	


 	  Quote: 	
		     Here I've suggested that you dump the #2 fat battery and

   the fat contactors associated with #2 master and crossfeed.

   Install a much smaller (7.2 AH, 5.5# 0.04 ohm) "brownout

   battery" and a pair of cube power relays wired such that

   the e-bus is supported ONLY by the brownout battery during

   engine cranking and only while the main bus is loaded so

   heavily that it cannot keep the EFIS from resetting.

     ~snip~
	


 	  Quote: 	
		     P.S. Here's an exemplar battery that seems well suited to

   this task:

http://aeroelectric.com/Mfgr_Data/Batteries/Panasonic/LC-R127R2P.pdf


	


 	  Quote: 	
		      Bob . . .

nuckolls.bob(at)cox.net
Guest

Posted: Thu Apr 24, 2008 8:23 am Post subject: Brownout Battery System P.S.

At 10:22 AM 4/23/2008 -0700, you wrote:



 	  Quote: 	
		  

<Thomas.N.Gautier(at)jpl.nasa.gov>



Bob,



      I looked at your Z13-8B(BrownOutBattery).pdf. It seems to me

that the only reason not to hook a battery like the Panasonic LC-R127R2P

directly to the endurance bus and do away with the brown-out

battery relay, alternate feed relay and the E-bus alternate feed switch

is that the battery won't charge properly through the diode

connecting the main bus to the endurance bus. However, what if you use

a shottky diode for the main bus/endurance bus connection?


	


    You always need the alternate feed relay (or switch). You don't want

    to leave  the e-bus hot when the airplane is parked. You also need a way

    to pre-flight the normal feedpath.

 	  Quote: 	
		      The power shottky on the Perihelion Design site apparently has about

0.2v forward drop. The Panasonic spec sheet you pointed to says, if I

read it right, that the battery needs 13.6-13.8 v terminal voltage to trickle

charge. So the brown-out battery should stay charged OK if the alternator

is regulated to supply more than 14.0 v, which I understand it has to do to

keep the main battery charged.


	


    The Shottky diode is alluring . . . but it needs to

    be insulated from ground and perhaps heat-sinked. It's

    also probably more expensive than the plastic cube relay.

    Having said that, since the brown-out battery is not needed

    to bolster capacity and is only expected to carry a load for

    tens of milliseonds per flight cycle, then the diode is certainly

    an option. Diode isolation would be the architecture of choice for the

    capacitor based brown-out technique discussed in the earlier

    post.



    But in either case, the alternate feedpath switch/relay is

    called for.

 	  Quote: 	
		       Am I missing something simple (or subtle) that makes this not work or

a bad idea?


	


    Keep in mind that during battery only operations, this same

    diode would be in series with a voltage source that is

    already depressed below 'normal' bus voltage. What you

    propose would probably function at some level. But for the

    moment, I'll have to continue to champion hard-closed contacts

    of relays and switches as being more efficient and lower cost

    of ownership without impacting system reliability.



    Now, a Shottky diode in the normal feedpath is certainly

    an option. But the "advantage" of lower voltage drop looses

    its luster . . . while the alternator is running you have

    watts-to-burn. So I'll suggest that the selection of this

    diode should include considerations of cost and convenience

    in mounting.



    Bob . . .

Display posts from previous:

	Matronics Email Lists Forum Index -> AeroElectric-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum