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ChrisM

Joined: 15 Nov 2014
Posts: 9

Posted: Mon Jan 19, 2015 2:51 pm Post subject: Power Generation without Battery?

Bob,



I am building a Carbon Cub - a lightweight experimental design for backcountry use. It will use a fully electrically dependent Lycoming engine. I plan on 1 battery/2 alternators, and I desire the system to run the engine with any 1 of those 3 failed.



I want to use a lithium battery for starting purposes only. I am not worried about battery only endurance with 2 other power sources.

Alternator technology is mature, but Li batteries seem to be still evolving. Some type of battery fault would seem be a likely failure mode in my planned system. (I'd like to monitor battery temp using a probe and my on board electronics, and to have some way to electrically isolate or even physically remove the battery).



I plan to use your Z12 or Z13 architecture.

People I speak with advise me that alternators (even the SD8) are dependent on a functioning battery in the system, and that they will cease to function if the battery fails or is taken offline.

Recent revelations regarding the Challenger/Aerovoltz scenario aside, there seem to still be legitimate issues with the current Li crop. At the very least they remain relatively unproven.



So I am concerned about the Li battery being a single point of failure capable of stopping the engine.



How can I design around this problem? 

Chris M

  [quote][b]

_________________
ChrisM

n801bh(at)netzero.net
Guest

Posted: Mon Jan 19, 2015 3:20 pm Post subject: Power Generation without Battery?

Pmag ?????

 

 

Ben Haas

N801BH

www.haaspowerair.com



--------

peter(at)sportingaero.com
Guest

Posted: Mon Jan 19, 2015 3:42 pm Post subject: Power Generation without Battery?

Use a lead acid battery? Something like a PC545 at 11.4 lb may be an acceptable weight penalty?

 Peter On 19 Jan 2015 23:03, "Chris Mullins" <mullincl(at)gmail.com (mullincl(at)gmail.com)> wrote:[quote]Bob,



I am building a Carbon Cub - a lightweight experimental design for backcountry use. It will use a fully electrically dependent Lycoming engine. I plan on 1 battery/2 alternators, and I desire the system to run the engine with any 1 of those 3 failed.



I want to use a lithium battery for starting purposes only. I am not worried about battery only endurance with 2 other power sources.

Alternator technology is mature, but Li batteries seem to be still evolving. Some type of battery fault would seem be a likely failure mode in my planned system. (I'd like to monitor battery temp using a probe and my on board electronics, and to have some way to electrically isolate or even physically remove the battery).



I plan to use your Z12 or Z13 architecture.

People I speak with advise me that alternators (even the SD8) are dependent on a functioning battery in the system, and that they will cease to function if the battery fails or is taken offline.

Recent revelations regarding the Challenger/Aerovoltz scenario aside, there seem to still be legitimate issues with the current Li crop. At the very least they remain relatively unproven.



So I am concerned about the Li battery being a single point of failure capable of stopping the engine.



How can I design around this problem? 

Chris M

   	  Quote: 	
		  



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[b]

jluckey(at)pacbell.net
Guest

Posted: Mon Jan 19, 2015 6:35 pm Post subject: Power Generation without Battery?

Chris,

If your mission profile could put you in the back country with ground support hundreds of miles away, you may want to consider a few ideas:

1. Consider changing architecture to 2 batteries & 1 alternator.  If your only battery goes dead or has diminished capacity due to extreme cold, you done.  Having an extra alternator won't get the engine started.



2. Maybe this is not the place for un-proven lithium battery technology.  Again, if your survival depends on it, you may want to go  w/ technology that has a proven track record.

-Jeff



 

     On Monday, January 19, 2015 3:51 PM, Peter Pengilly <peter(at)sportingaero.com> wrote:

  

   



 Use a lead acid battery? Something like a PC545 at 11.4 lb may be an acceptable weight penalty?

 Peter

 On 19 Jan 2015 23:03, "Chris Mullins" <mullincl(at)gmail.com (mullincl(at)gmail.com)> wrote:

[quote]Bob,



I am building a Carbon Cub - a lightweight experimental design for backcountry use. It will use a fully electrically dependent Lycoming engine. I plan on 1 battery/2 alternators, and I desire the system to run the engine with any 1 of those 3  failed.



I want to use a lithium battery for starting purposes only. I am not worried about battery only endurance with 2 other power sources.

Alternator technology is mature, but Li batteries seem to be still evolving. Some type of battery fault would seem be a likely failure mode in my planned system. (I'd like to monitor battery temp using a probe and my on board electronics, and to have some way to electrically isolate or even physically remove the battery).



I plan to use your Z12 or Z13 architecture.

People I speak with advise me that alternators (even the SD8) are dependent on a functioning battery in the system, and that they will cease to function if the battery fails or is taken offline.

Recent revelations regarding the Challenger/Aerovoltz scenario aside, there seem to still be legitimate issues with the current Li  crop. At the very least they remain relatively unproven.



So I am concerned about the Li battery being a single point of failure capable of stopping the engine.



How can I design around this problem? 

Chris M

   	  Quote: 	
		  



_blank">www.aeroelectric.com

.com" target="_blank">www.buildersbooks.com

="_blank">www.homebuilthelp.com

="_blank">www.mypilotstore.com

ank">www.mrrace.com

_blank">http://www.matronics.com/contribution

ist" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List

tp://forums.matronics.com



	


[b]

nuckolls.bob(at)aeroelect
Guest

Posted: Wed Jan 21, 2015 5:59 am Post subject: Power Generation without Battery?

At 16:49 2015-01-19, you wrote:

Bob,

I am building a Carbon Cub - a lightweight experimental design for 

backcountry use. It will use a fully electrically dependent Lycoming 

engine. I plan on 1 battery/2 alternators, and I desire the system to 

run the engine with any 1 of those 3 failed.



   Under what scenario do you perceive that a battery

   becomes unavailable to you?



I want to use a lithium battery for starting purposes only. I am not 

worried about battery only endurance with 2 other power sources.



   Okay . . .

Alternator technology is mature, but Li batteries seem to be still 

evolving. Some type of battery fault would seem be a likely failure 

mode in my planned system. (I'd like to monitor battery temp using a 

probe and my on board electronics, and to have some way to 

electrically isolate or even physically remove the battery).



I plan to use your Z12 or Z13 architecture.



   Which #2 alternator are you considering?

People I speak with advise me that alternators (even the SD8) are 

dependent on a functioning battery in the system, and that they will 

cease to function if the battery fails or is taken offline.



    Not true. Once they are up and running, all alternators

    will continue to run self-excited unless 'stalled' by

    a LARGE load, like 200W landing light or an electro-

    hydraulic pump motor. The SD-8 can be installed to

    self-excite (See Z figures). Many alternators on

    Lycoming engines will self excite due to their

    high operating speeds with the popular pulley

    ratios.



Recent revelations regarding the Challenger/Aerovoltz scenario aside, 

there seem to still be legitimate issues with the current Li crop. At 

the very least they remain relatively unproven.



    It's not one 'crop' but a garden . . . albeit

    infested with some weeds. The type

    certificated lithium products like True Blue

    have 'full up' battery management systems that

    are quite capable of preventing events like that

    which plagued the Challenger owner. Further,

    had the Challenger owner availed himself of

    the knowledge and experience freely offered

    from the pages of this List and DOZENS of

    other sources, he would have caught the mis

    behaving rectifier-regulator before it became

    antagonistic to his battery.



    I'm working on the 'frosting' article to a

    series I did in Kitplanes on lithium batteries.

    A major feature of the article points out

    the constellation of design and marketing

    approaches for lithium cranking batteries

    in particular and consumer off-the-shelf

    cells in general.



    It will also discuss the range of offerings

    for 'battery management systems' which can

    range from a simple fuse built into one

    end of a cell . . . up to a bucket full of

    electronics and software that costs nearly

    as much as the battery itself!

So I am concerned about the Li battery being a single point of 

failure capable of stopping the engine.



    Engine stoppage due to failed battery? Not

    if you take the time to understand how all

    those bits and pieces fit together to solve

    your particular puzzle. If you want to

    go lithium, go EarthX (Full up BMS). There

    are some up-n-comers nipping at EarthX's

    heels . . .



How can I design around this problem?



    Simple . . . not necessarily easy but simple.

    Hang out here. Read. Ask questions (which

    are already under way . . . good for you!).

    When you hear/read/observe some bit of

    information from other sources, bring them

    here to the List for sharing/sifting of

    the simple-ideas in physics that define

    REAL performance and risks.



    Share your thoughts about load analysis,

    qualify your "plan-b" to deal with failures.

    Your misgivings are real but I suggest

    they are borne more of ignorance than of physical

    limits to performance of products that are

    thoughtfully and skillfully crafted.



    It's your ability to recognize those skills

    that will carry you forward with confidence.



    By the way, your 'advisors' who speak of

    alternator/battery relationships might enjoy

    joining us here too . . . their advise is

    dated and/or inaccurate.

   Bob . . .

ChrisM

Joined: 15 Nov 2014
Posts: 9

Posted: Wed Jan 21, 2015 12:00 pm Post subject: Re: Power Generation without Battery?

Bob,

I think the most likely battery failure modes would be temperature related due mild overcharging/cell imbalance/high ambient temperatures. I think I'll be pretty protected from a runaway thermal overload due to frank over voltage as I will use your Z figures with overload protection/notification. An internal short may also be more likely with lithium than with lead acid.



Regarding alternator #2: I request your advice. Running the engine with the EFII requires 10 amps - mostly for electric fuel pump. I think I need perhaps 15 amps for a comfort margin and to run the radio. Output curve vs rpm is significant considering fuel and ignition function are at stake. But this is a vfr aircraft and I can navigate and fly with nothing but the engine running.

So the SD8 does not have adequate output.

Perhaps adapting one of B&C's larger units intended for Continentals?  Wind my own? Hopefully something off the shelf though!



I contacted B&C on the self/persistent excitation issue and was advised that the SD8 requires a battery in the system to operate the regulator. He referred me to you. Also called Plane Power as it seemed their internally regulated design should be able to continue to run following removal of external battery power, but was advised not. Answers may have been tainted by my emphasis about actually keep the engine running!



I don't think I have any large loads in the plane which would tend to stun the self-excited alternator. Think I may make a small placard to remind about being gentle with manipulations if running under such circumstances.

I believe you drew Z12 and Z13 prior to predominance of 100% electrically dependent engines. They both show a magneto in the system for example.

Do you feel these Z figures are appropriate for adapting to electrically dependent engines using a lead acid battery?



Do you think Z12/13 are reasonable for use with a current technology (eg EarthX) Li battery?

Which Z do you favor and why?



If yes, is there some means to enhance the alternators propensity to continue to produce power following battery failure?



What do you recommend for a first and second alternator for my system? Minimum output needed is 15 amps at perhaps 1800 engine rpm. Weight is a factor for my setup.



Thank you very much for helping me understand how all these bits and pieces do fit together.

Your willingness to offer your expertise and experience answering questions like these is very generous.

Chris M

_________________
ChrisM

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Jan 23, 2015 5:43 am Post subject: Power Generation without Battery?

At 14:00 2015-01-21, you wrote:

 --> AeroElectric-List message posted by: "ChrisM" <mullincl(at)gmail.com>



 Bob,

 I think the most likely battery failure modes would be temperature related due mild overcharging/cell imbalance/high ambient temperatures.

 I think I'll be pretty protected from a runaway thermal overload due to frank over voltage as I will use your Z figures with overload protection/notification. An internal short may also be more likely with lithium than with lead acid.



    I think you're over-worrying the design decisions before you.   Keep in mind that the aviation industry has a rich history   of what works and lessons learned for what doesn't.

 

    If you sort through the NTSB accident reports, you will be   hard pressed to find one that has root cause in failure of   an electrical system component to perform as advertised. Even when   such stories are found, we read about accidents that just   didn't need to happen based on poor architecture, craftsmanship   and/or operational decisions . . . NOT borne out of any   failure-to-perform to specifications.

 



   http://tinyurl.com/mwo3f4x



   http://tinyurl.com/kv7eugm



   http://tinyurl.com/msfmldj

 



    A well maintained battery (meaning you don't simply   run it until it doesn't crank the engine any more)   is the single most reliable power source on the airplane.   LIMITED in amount of energy stored but a reliable   resource when that energy is skillfully managed.

 

    Risk of shorted cells in a well managed SVLA based    system is essentially zero. Even the lithium incident   recently discussed had root cause in severe over-charging   from a condition that went unnoticed by the pilot for   a LONG period of time.

 



 Regarding alternator #2: I request your advice. Running the engine with the EFII requires 10 amps - mostly for electric fuel pump.



    Are these published, MEASURED numbers? That's a LOT   of power for a task that takes less than 5A in my   1987 pickup. Are there examples of your proposed system   flying? Have any of those operators shared any current   draw observations?



  I think I need perhaps 15 amps for a comfort margin and to run the radio. Output curve vs rpm is significant considering fuel and ignition function are at stake. But this is a vfr aircraft and I can navigate and fly with nothing but the engine running.



 

 So the SD8 does not have adequate output.



    The SD-8 is a 10A max machine but it does have   adequate power for the majority of elegantly   crafted architectures



 Perhaps adapting one of B&C's larger units intended for Continentals?  Wind my own? Hopefully something off the shelf though!



    Wind one? If the over-riding concern driving this thread   is system reliability for an airplane that clearly isn't   going to spend hours at rarified heights . . . any   performance advantages for 'going hi-tech' are not   going to be realized. The most proven recipes for success   in system reliability used independent ignitions either   self-contained (magnetos, p-mags) or very low current   demand (light speed, et. als.)

 

    Electronic fuel injection for a back-country, puddle   jumping pick-em-up truck only adds complexity with limited   return on investment.

 

    If it were my airplane:  Lyc with p-mags or light speed   ignition, L-40 belt driven alternator, SD-8 pad driven   alternator, well maintained SLVA battery (or EarthX   if you're ready to $spend$ just for weight reduction.)

 

    This combination has evolved with a track record of   ancestral architectures going back 100 years. Clearly,   your project has the potential for being a great   fun-machine. But time, talent and resources being contemplated   to make it look more like a Lancair IVP only drives up complexity,   adds to your burdens for understanding all the nuances of   its architecture, drives up worry-pressures and adds   almost nothing to observable performance. 

 



 I contacted B&C on the self/persistent excitation issue and was advised that the SD8 requires a battery in the system to operate the regulator. He referred me to you. Also called Plane Power as it seemed their internally regulated design should be able to continue to run following removal of external battery power, but was advised not. Answers may have been tainted by my emphasis about actually keep the engine running!



    Actually, self-excitation on the SD-8 was discussed   here on the List some time back. Figure Z21 in the   'Connection illustrates the concept for adding a few   components to keep PM alternator's rectifier/regulators   'awake' sans battery. 

 



 I don't think I have any large loads in the plane which would tend to stun the self-excited alternator. Think I may make a small placard to remind about being gentle with manipulations if running under such circumstances.

 I believe you drew Z12 and Z13 prior to predominance of 100% electrically dependent engines. They both show a magneto in the system for example.

 Do you feel these Z figures are appropriate for adapting to electrically dependent engines using a lead acid battery?



 Do you think Z12/13 are reasonable for use with a current technology (eg EarthX) Li battery?

 Which Z do you favor and why?



 If yes, is there some means to enhance the alternators propensity to continue to produce power following battery failure?



     If you spend as much time taking care of a battery as    you do worrying about it failing, then it's not going    to fail. Taking care of it means, "operate it within    well established limits and preventative maintenance    to verify integrity."

 



 What do you recommend for a first and second alternator for my system? Minimum output needed is 15 amps at perhaps 1800 engine rpm. Weight is a factor for my setup.



     Z-13/8, simple ignition/fuel delivery, battery optional    but DEMANDING of your attention no matter what alternators    or battery is installed. We tend to worry more about changing    oil in the engine or watching tire tread wear than to    track and verify battery performance. Yet more unhappy    days in the cockpit are rooted in poorly archtiectured/    maintained electrical systems than for dirty oil or worn    tires.

     Bob . . .     [quote][b]

user9253

Joined: 28 Mar 2008
Posts: 1908
Location: Riley TWP Michigan

Posted: Sat Jan 24, 2015 7:10 am Post subject: Re: Power Generation without Battery?

Lightspeed and others recommend connecting electronic ignition directly to the battery.  Since Lithium batteries have been known to short out, maybe they should not be used.  If the battery shorts out, so will the alternators be shorted.

  Another failure mode to be considered is a failed master contactor shortly after takeoff.  That is not very likely to happen, but it could.  Regardless of what the manufacturers say, an alternator could keep supplying power to the aircraft electrical system.  Thus the pilot would not know that the master contactor has opened.  If the duration of the flight is longer than the energy stored in the battery (likely with a Li battery), then the engine will quit.  A solution to the failed master contactor scenario is a relay in parallel (disabled during engine cranking).

  Even if these failure modes are unlikely, everything needs to be considered when designing an electrical system.  Accidents happen sometimes due to unlikely and unexpected chain of events.

Joe

_________________
Joe Gores

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Jan 25, 2015 9:45 am Post subject: Power Generation without Battery?

At 09:11 2015-01-24, you wrote:

 	  Quote: 	
		  



Lightspeed and others recommend connecting electronic ignition 

directly to the battery.


	


    . . . a sentiment that has been echoed in the AEC publications

    for a long time. Fuel pumps too . . . any component which depends

    on DC to keep the engine running . . .



 	  Quote: 	
		     Since Lithium batteries have been known to short out, maybe they 

 should not be used.


	


    SLVA batteries never short?

 	  Quote: 	
		     If the battery shorts out, so will the alternators be shorted.


	


    . . . okay, step through the FMEA for a shorted cell in

    any battery. How will the event manifest? How will the

    pilot become aware of it? What is the recommended plan

    of action to be taken by the pilot? Most important . . .

    what features can be incorporated into the full-up system

    to offer a pilot the best response to the event?



 	  Quote: 	
		     Another failure mode to be considered is a failed master 

 contactor shortly after takeoff.


	


    Again, step through the FEMA . . .



 	  Quote: 	
		     That is not very likely to happen, but it could.  Regardless of 

 what the manufacturers say, an alternator could keep supplying 

 power to the aircraft electrical system.


	


   Yes . . . consider the plots of data I took on an exemplar

   SD-8 at B&C about 20 years ago



http://tinyurl.com/n5yd3vw



   In particular, page 9 of the document that cites 14.5v output

   at 9.7 amps with a 10KuF 'smoothing' capacitor and NO BATTERY.

   One a quality we've not discussed here is the value of the

   legacy 'smoothing' capacitor might add in improving NO BATTERY

   performance of the rectifier-regulator. A question I will explore

   in the future.

 	  Quote: 	
		    Thus the pilot would not know that the master contactor has 

 opened.  If the duration of the flight is longer than the energy 

 stored in the battery (likely with a Li battery), then the engine 

 will quit.  A solution to the failed master contactor scenario is a 

 relay in parallel (disabled during engine cranking).


	


   That's one solution . . . are there others?



 	  Quote: 	
		     Even if these failure modes are unlikely, everything needs to be 

 considered when designing an electrical system.  Accidents happen 

 sometimes due to unlikely and unexpected chain of events.


	


   . . . but with some tempering based on lessons learned

   and probabilities based on history. Yeah, on occasion

   some airplanes throw a prop . . . bad bolts? Probably

   not. Bad installation of bolts? Probably. Broken

   crankshaft . . . that's a stretch. But again, history

   has demonstrated the MAJOR cause of uncomfortable

   termination of flight is inattention to simple-ideas

   with performance histories rich in data.



   Bob . . .

user9253

Joined: 28 Mar 2008
Posts: 1908
Location: Riley TWP Michigan

Posted: Sun Jan 25, 2015 1:30 pm Post subject: Re: Power Generation without Battery?

 	  Quote: 	
		  I'd like to monitor battery temp using a probe and my on board electronics, and to have some way to electrically isolate or even physically remove the battery 	


Here a links to thermocouples.  Most EMS or EFIS have inputs for type J.

http://www.omega.com/pptst/WT.html

http://www.omega.com/pptst/SA2.html

If the EFIS alarms with temperature rise, the master switch can be shut off.



 	  Quote: 	
		  So I am concerned about the Li battery being a single point of failure capable of stopping the engine. 

How can I design around this problem? 	


Are there any permanent magnet alternators (dynamo) available for your engine?  One possibility (and I am not necessarily recommending this) is to dedicate a dynamo to supply electrical power to only one fuel pump and one ignition, keeping this circuit completely isolated and independent of the rest of the aircraft electrical system (except for common ground).

Joe

_________________
Joe Gores

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Jan 25, 2015 3:13 pm Post subject: Power Generation without Battery?

At 15:30 2015-01-25, you wrote:

 --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com>



 

 > I'd like to monitor battery temp using a probe and my on board electronics, and to have some way to electrically isolate or even physically remove the battery



 Here a links to thermocouples.  Most EMS or EFIS have inputs for type J.

  http://www.omega.com/pptst/WT.html

  http://www.omega.com/pptst/SA2.html

 If the EFIS alarms with temperature rise, the master switch can be shut off.



     But where do you put a thermocouple?  In a   4x4 array of cells, there are 16 potential   failures. How can you be certain that monitoring   any particular location outside the battery will   offer timely notification of a failure on any   of the 16 cells inside?

 



    What constitutes an alarming temperature rise?

 

    Once that condition is noted, what value is there   in any pilot action. Shut off the battery? Jettison   the battery? 

 

 



 > So I am concerned about the Li battery being a single point of failure capable of stopping the engine. 

 > How can I design around this problem?



     Design a system that doesn't set batteries on fire (timely   notification of or reaction to over voltage) and perhaps   incorporate batteries with full-up Battery Management Systems   that will function to PREVENT such events as opposed to reacting   to the event AFTER it occurs. 

 



 Are there any permanent magnet alternators (dynamo) available for your engine?  One possibility (and I am not necessarily recommending this) is to dedicate a dynamo to supply electrical power to only one fuel pump and one ignition, keeping this circuit completely isolated and independent of the rest of the aircraft electrical system (except for common ground).



     Please make the argument for the battery (of any chemistry)   NOT being the most reliable source of energy on the   airplane. We've read narratives for all manner   of puffed-up and/or vented-dry SVLA batteries . . .   some of which have indeed experienced internal fires.

 

    ALL such cases were preceded by a sustained ov even   that went unnoticed. Batteries don't instantly go   POOF when the alternator runs away. To this date, are   we aware of ANY battery in distress that was NOT   triggered by an event borne of poor system architecture   or operator inattention?

    Bob  . . .     [quote][b]

user9253

Joined: 28 Mar 2008
Posts: 1908
Location: Riley TWP Michigan

Posted: Sun Jan 25, 2015 4:16 pm Post subject: Re: Power Generation without Battery?

Chris,

My mistake, I should have read your first post more closely.  You do intend to use the SD-8 dynamo.

  The Rotax 912i fuel injected engine has two dynamos, one for the engine and one for the rest of the aircraft.  The ignition and fuel pumps can also be powered by the other dynamo if necessary.

Joe

_________________
Joe Gores

user9253

Joined: 28 Mar 2008
Posts: 1908
Location: Riley TWP Michigan

Posted: Sun Jan 25, 2015 4:41 pm Post subject: Re: Power Generation without Battery?

 	  Quote: 	
		  Please make the argument for the battery (of any chemistry) NOT being the most reliable source of energy on the airplane. 	


I agree that SVLA are very reliable.  I am not very knowledgeable about the Lithium batteries except for the news reports which sensationalize the fire without explaining why it happened.  If you think that the Lithium batteries are safe (if properly charged and discharged) for use in aircraft, then that is good enough for me.  But I will wait until the price comes down to the level of lead acid batteries before buying a Lithium.  In the mean time, I will keep my plane light weight by watching what I eat.  

  Joe

_________________
Joe Gores

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Jan 25, 2015 6:18 pm Post subject: Power Generation without Battery?

At 18:16 2015-01-25, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com>



 Chris,

 My mistake, I should have read your first post more closely.  You do intend to use the SD-8 dynamo.

   The Rotax 912i fuel injected engine has two dynamos, one for the engine and one for the rest of the aircraft.  The ignition and fuel pumps can also be powered by the other dynamo if necessary. 	


   The last time I dug through the MM on a 912, a

   constellation of windings on the PM alternator

   stator core were defined as follows:



 [img]cid:.0[/img]



   4 each, trigger coils for spark timing of the

           8 plugs in pairs (waste spark). These

           will be a low voltage, low energy

           signal to the ignition modules.



   2 each, capacitor charging coils, one for

           each module. These are moderate energy,

           high voltage windings that charge a

           capacitor with each pass of the magnet.

           This few hundred volts of capacitor

           charge is stepped up in coils to the

           killovolt levels needed for plugs.



   1 each, tachometer signal coil. Another

           low voltage, low energy signal generator

           for an electronic tach.



   1 each, PM alternator coil. High energy, high

           current in the 250W class. This is the

           only winding available to drive any

           sort of rectifier-regulator to operate

           ship's electro-whizzies.



           All other windings are separate and dedicated

           to their respective tasks thus making ignition

           systems completely independent of the power

           generation system.



           Some Rotax installations include aa SECOND,

           optional belt driven alternator in the 40-55A class.

           This second alternator has been teamed with

           the integral PM alternator in a Figure Z-13/8

           configuration on several OBAM aircraft . . .



           I've seen some pad driven alternators on

           Rotax engines . . . in the spot for

           vacuum pumps. But this pad is slow and

           I don't think THAT particular #2 alternator

           was very practical.



           In any case, only one coil of eight on the

           back of a Rotax 912/914 generates power

           for ship's electrical needs.



            



 

   Bob . . .

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user9253

Joined: 28 Mar 2008
Posts: 1908
Location: Riley TWP Michigan

Posted: Sun Jan 25, 2015 6:41 pm Post subject: Re: Power Generation without Battery?

The Rotax fuel injected engine is new, only having been for sale for the last year or two.  It is an electrically dependent engine, not only for the ignition, but also for the high pressure fuel pumps.  Thus, the electrical system needs to be fail safe.  Below is an excerpt  from the installation manual.

http://www.flyrotax.com/customer-serviceImpressum/technical-publications.aspx

Joe



 	  Quote: 	
		  The internal generator has two isolated coils integrated (individual generators). During the starting operation, the EMS system is powered by the battery. With sufficient speed generator B takes over this function. After the EMS system check, generator A takes over the supply of the EMS system (engine), if the switching threshold is exceeded. Generator B is then used to supply the aircraft instruments and for charging the battery.

Generator A 14.2 V/16 A (220 W nominal capacity at 20°C/68 °F)

Generator B 14.2 V/30 A (420 W nominal capacity at 20°C/68 °F)



If generator A fails, generator B takes over its functions.  The onboard computer and the instruments will be supplied by the battery. The battery will no longer be charged!



If generator B fails, the battery will no longer be charged. The engine still runs on generator A and the instruments will be supplied by the battery. The function of the instruments depends on the state of charge of the battery.

For monitoring the battery voltage and to ensure that the battery is charged, a voltmeter and ammeter is necessary.

_________________
Joe Gores

rlborger(at)mac.com
Guest

Posted: Sun Jan 25, 2015 7:07 pm Post subject: Power Generation without Battery?

Bob,



FWIW, I have one of those (Nippon Denso) alternators on the vacuum pad of my 914.  It is actually capable of producing more amps than the ROTAX built-in alternator.  But it takes 2500 rpm for it to come online. 



Best regards,

Robert Borger, President

Geowhiziks & Doodlebugging, Inc.

Certified Petroleum Geophysicist AAPG#101

3705 Lynchburg Dr.

Corinth, TX 76208-5331

(C) 817-992-1117



Sent from my iPad



 	  Quote: 	
		   On Jan 25, 2015, at 19:17, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com> 


	


 	  Quote: 	
		             I've seen some pad driven alternators on

           Rotax engines . . . in the spot for

           vacuum pumps. But this pad is slow and

           I don't think THAT particular #2 alternator

           was very practical.

ChrisM

Joined: 15 Nov 2014
Posts: 9

Posted: Fri Jan 30, 2015 10:05 am Post subject: Re: Power Generation without Battery?

Bob,

Thanks to you and other participants for help with my questions.

Interesting that you are feeling so confident in the application of Li batteries. This is really a significant step forward in technology for small aircraft.



You emphasized to "operate (Lithium battery) within well established limits and preventative maintenance to verify integrity." Will you elaborate regarding how this looks with Li?  You have mentioned in the past about the lack of data from many manufacturers, and the lack of lead acid equivalency. Do you feel the BMS used by EarthX is a final equilibrator here?  



The  advanced EFII system I have been evaluating may be a bit too far up the ladder for my project, as you pointed out. The 10 ampere requirement quoted was per email from manufacturer and is for both the fuel and ignition systems. Majority apparently consumed by the fuel pump - one of two runs at a time to pressurize a fuel rail.



Anyway, I am currently favoring a pullback to a set of P Mags, mechanical fuel injection, a single Li battery with a small detached back up, and a single alternator. This set up should perform similarly in practical terms, and be very reliable and light.

 

At least I have a nice head start on my Lance Air project!

_________________
ChrisM

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Jan 31, 2015 9:06 am Post subject: Power Generation without Battery?

At 12:05 2015-01-30, you wrote:

 --> AeroElectric-List message posted by: "ChrisM" <mullincl(at)gmail.com>



 Bob,

 Thanks to you and other participants for help with my questions.

 Interesting that you are feeling so confident in the application of Li batteries. This is really a significant step forward in technology for small aircraft.



  I have not said that it's a "step forward" . . . in fact,

  I have raised questions as to the economics for the transition

  to lithium. I will assert that lithium is an alternative

  ingredient that may well be an appealing recipe for success.

  I don't yet see a concise definition of 'success'.

   

  There are three separate lines of inquiry that influence the

  choice to incorporate lithium batteries into your personal

  elegant solution.



  Integration: It's no different than the study of how

  transistors evolved with significant milestones marked

  by the relative fragility of the PNP germanium 

  transistors that first flew in airplanes. Devices later

  displaced with more robust NPN silicon. More recently,

  the power mosfet is King Silicon. EVERY evolutionary

  plateau was an improvement in performance, robustness

  and service life. However, EVERY step up required major

  changes to the circuitry and design philosophy to fully

  exploit what the new device had to offer. One could not

  simply pull out the old and plug in the new. This is

  the foundation for my distaste of popular marketing

  hype citing "lead-acid equivalency".



  Lithium is equivalent to nothing . . . its greatest

  advantages cannot be fully exploited without careful

  attention to just how this ingredient 'fits' into

  the recipe for success. 



  Cost of Ownership: When Burt Rutan was putting the sharp

  pencil to the design of Voyager, weight was a critical

  consideration.



  He told us that it takes 5 pounds of fuel to carry

  one pound of airplane around the world. Every pound

  removed from empty weight removes 6 pounds from gross

  weight at takeoff. Nearly one gallon more fuel. One gallon

  at end of mission would carry Voyager another hundred

  miles or so. But there were prices to pay. The materials

  to build such a 'featherweight' airplane with any structural

  integrity were very expensive. Further, fuel unique mission

  requirement multiplies the weight of the airplane by 6 times

  called for a fuel tank with wings having very attractive

  l/d ratios . . . at the sacrifice of handling qualities.

  Dick Rutan confessed that the airplane scared the hell

  out of him . . . he had nightmares of dying in that

  airplane. Without the fine support of King Radio for

  an autopilot that would handle this winged beast,

  the around-the-world mission would have humanly

  impossible. Without pedantic attention to weight,

  sometimes a great cost, the mission might not have been

  possible.



  Risk: Properly conducted FMEA seek to study, discover,

  classify, understand and ultimately mitigate all the

  ways that the product can first, cease to preform

  intended duties as one of many players in the orchestra.

  Then,  mitigate failures that put the entire system at risk for

  catastrophic collapse. It's one thing for the cello

  player to break a string . . . quite another for

  to be sneezing H1N1 into the surrounding environment.



 You emphasized to "operate (Lithium battery) within well established limits and preventative maintenance to verify integrity." Will you elaborate regarding how this looks with Li?  You have mentioned in the past about the lack of data from many manufacturers, and the lack of lead acid equivalency. Do you feel the BMS used by EarthX is a final equilibrator here?  



  The purveyors of lithium are the first folks to assert

  that battery management systems are always a 'good'

  idea. What ever form they take, the BMS mitigates risk

  for catastrophic failure. Just how the BMS is configured

  and applied in practice a big factor in performance, risk

  and cost of ownership. It's unreasonable and added risk

  to expect the consumer (OBAM aircraft builder) to take

  on yet another task that amounts to micro-managing the

  lithium physics. Especially when compared to the mature,

  relatively docile qualities of lead-acid. BMS may not

  be the 'final' answer to the svla vs. lithium decision

  but certainly a major consideration.



  An this still leaves the question I've asked and

  nobody has come forward to answer, "What are the

  numbers . . . how will the smaller weight and volume

  numbers manifest in the performance and utility of

  say, an RV7 presently fitted wity a PC680? Shorter

  takeoffs? Higher mountains to challenge, cleared

  out space to store your sandwiches?



  Boeing's considerations for battery weight were but one

  component in a HUGE model of cost/benefit ratios. The numbers

  they considered enticed them to spend $millions$ in making

  the switch to lithium. What are YOUR numbers? 



 

 The  advanced EFII system I have been evaluating may be a bit too far up the ladder for my project, as you pointed out. The 10 ampere requirement quoted was per email from manufacturer and is for both the fuel and ignition systems. Majority apparently consumed by the fuel pump - one of two runs at a time to pressurize a fuel rail.



  Yes . . . and I've heard 'up and running' numbers on

  that system 'quoted' from 6 to 10 amps . . . but I have

  yet to discover published data that speaks to the real

  energy requirements for this system.



  People may snicker at my insistence that the purveyors of

  lithium come forth with "all the numbers" . . . like

  Hawker/Enersys and virtually all contemporaries. But as

  Lord Kelvin often  opined, "without the numbers you have

  barely scratched the surface of the science." I will build

  on that sentiment by suggesting that the decision should not

  devolve to preferring Big Macs just because they taste good

  without knowing how they integrate into the energy

  conversion/management system of a very complex machine.

  Questions that remain undiscovered, unasked, unanswered

  and/or ill-considered may bring the system down no matter

  how good the product tasted.



  EFII "owes" you the same quality of numbers that we expect

  from Rotax, AeroVoltz, Icom, Smiley Jack's Prop Shop

  . . . or anybody else that wants to play honorably and capably

  in this sandbox.



 Anyway, I am currently favoring a pullback to a set of P Mags, mechanical fuel injection, a single Li battery with a small detached back up, and a single alternator. This set up should perform similarly in practical terms, and be very reliable and light.



  Sounds like a considered  move . . . what now are your

  electrical system numbers insuring comfortable termination

  of flight limited only by fuel aboard?



  Are you going to have a vacuum pump? Why waste a

  perfectly good energy source by covering the pump

  pad with a plate of aluminum? After nearly 20 years

  of sifting the numbers, FMEA scenarios, costs of

  ownership and performance, I suggest that Figure Z-13/8

  is as near 'perfection' for flight system reliability

  . . . assuming of course that you don't burden it with

  an 120 watt engine support demands.



  You speak of two batteries . . . why? One or both lithium?

  Can you share your FMEA and cost of ownership reasoning?

  Exactly how will that savings of wight manifest in performance

  or utility of your airplane . . . and at what cost of

  hours to integrate and maintain performance at minimum

  levels throughout the service life of the battery?



  Z-13/8 will keep your panel lit and allow you to

  run any battery until it won't crank the engine any

  more. The cost of ownership for the 4 pound wight

  penalty of an SD-8 is far, Far, FAR lower than

  that of any second battery you might choose to

  lug around ESPECIALLY lithium.



 

   Bob . . .     [quote][b]

ChrisM

Joined: 15 Nov 2014
Posts: 9

Posted: Tue Feb 03, 2015 2:50 pm Post subject: Re: Power Generation without Battery?

Hi Bob,

Thank you for hanging in there with me as I continue to learn. I feel I am getting my moneys worth.



Most of us here are really interested in how Li will fit in the OBAM aircraft world.  Based on my own study and what I have learned here, I do feel Li is a good choice for my design. You asked about the definition of design success - Doesn't that change a bit with each aircraft and mission? Refining “success” is one of the satisfying things about working with OBAM aircraft. Each design decision, by itself, can be considered to be a success or not depending on how wisely risks and benefits which apply to the specific problem at hand are evaluated and applied.



I think design success for me does involve a Li battery. Seems to me that Li is becoming the clear choice for most light weight aircraft with electrical systems tasking the battery primarily with starting duties. I'll try and explain my thinking...



One of the major seminal concepts for the plane I am constructing is light weight. It's a clean sheet design, and weight figured in all the decisions made by the airframe engineers. If weight had been ignored in a few of those decisions, it wouldn't have crippled the design. But if weight consciousness was repeatedly ignored thru a thousand decisions, then it would have resulted in a  poor/heavy design. 



I think your question “What are the performance improvement numbers.....” is narrowly phrased to provoke thought about the bigger picture. It points to the folly of making a decision which favors weight savings excessively in favor of other parameters like cost, reliability etc etc. Practically speaking, a single decision to adopt a heavy solution in an airplane cannot easily be quantified from a performance functionality point of view. But I think that still qualifies as a compromised decision from an engineering point of view, if lightweight is one legitimate priority for the aircraft. I think decisions as builder need to remain generally in alignment with the original concept, or one probably should be building a different aircraft.  



My understanding from lurking here is that, aside from endurance, Li with a BMS, has become a functionally equivalent stand-in for lead acid. If light weight is one prominent priority for a  given design, the 10# or so one saves, for the $200 or so it costs, is very cost effective when compared with widely accepted weight saving techniques. The real engineers have already spent a lot more than that on solutions to eliminate 10#. One of my goals as builder and supplemental designer, is to not screw up their work. I agree that impact on performance cannot  be specifically quantified, but that has more to do with the nature of aviation itself. But the 10# weight reduction is objective, and it's a legitimate achievement because we do know it translates to improved performance. 



I think I'll carry a small spare power source until I have personal experience with the Li technology. My single Li battery will be the only way to start the engine. I don't want to be surprised by some nuance of Li technology after landing on a gravel bar. Pmags apparently will not self excite with hand propping – they must have some external power to initialize function. The BMS in an EarthX apparently shuts off the battery under certain circumstances – need to learn more about it. Resetting the BMS requires external power. EarthX seems to have come up with this device:  http://earthxmotorsports.com/shop/earthx-jump-pack/



I appreciate comments questioning costs of presumptively assuming 10 amps for the EFII, when the  figures might be only partially vetted or motivated by some other issue besides real engineering. If I end up going that route I will explore thoroughly.



I think no vacuum pump for this plane. Single alternator. If the battery or alternator fails, I will turn off the electrical system and navigate by tablet or smart phone. I'll use the radio on arrival at a landing site if it's operational  - or not.



I don't think the SD-8 does anything but add unneeded weight to the Pmag/Bendix type injection design. I don't need additional inflight power sources with self sustaining fuel and ignition systems. I think my weakest link could be engine starting, and the SD-8 won't help with that. 

I am going to focus on getting the Li done right!

Chris M

_________________
ChrisM

Tundra10

Joined: 14 Jun 2010
Posts: 102
Location: Scarborough, Ontario

Posted: Wed Feb 04, 2015 9:07 am Post subject: Power Generation without Battery?

If I remember correctly, I asked the hand propping question of the  

E-Mag Ignitions folks at AirVenture a couple of years ago.



I think the response was to carry a regular 9V battery with you, since  

it would be enough to get the plane started.



That information would need to be verified and the concept would need  

to be tested, and you would need an elegant way to connect it, but if  

you plan to be away from civilization, it might be an elegant solution.



Jeff Page

Dream Aircraft Tundra #10

 	  Quote: 	
		   Time: 02:52:18 PM PST US

 Subject: Re: Power Generation without Battery?

 From: "ChrisM" <mullincl(at)gmail.com>



<--- SNIP --->
	


 	  Quote: 	
		   I think I'll carry a small spare power source until I have personal  

 experience with the Li technology. My single Li battery will be the  

 only way to start the engine. I don't want to be surprised by some  

 nuance of Li technology after landing on a gravel bar. Pmags  

 apparently will not self excite with hand propping  they must have  

 some external power to initialize function. The BMS in an EarthX  

 apparently shuts off the battery under certain circumstances  need  

 to learn more about it. Resetting the BMS requires external power.  

 EarthX seems to have come up with this device:   

 http://earthxmotorsports.com/shop/earthx-jump-pack/


	


<--- SNIP --->



 	  Quote: 	
		   ChrisM



 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=438031#438031

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