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battery question

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kenryan

Joined: 20 Oct 2009
Posts: 426

Posted: Tue Jun 21, 2016 9:11 am Post subject: battery question

I am installing a Rotax 914 which requires an electric fuel pump to run. My electrical system architecture will have the primary pump running directly off the integrated generator. The primary pump will be the ONLY load on the generator. The backup pump will run off the battery bus, connected to the external alternator. My question is, does it make any sense to include a battery in the generator/primary pump system?

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Jun 21, 2016 10:46 am Post subject: battery question

At 12:09 PM 6/21/2016, you wrote:

  	  Quote: 	
		  I am installing a Rotax 914 which requires an electric fuel pump to run. My electrical system architecture will have the primary pump running directly off the integrated generator. The primary pump will be the ONLY load on the generator. The backup pump will run off the battery bus, connected to the external alternator. My question is, does it make any sense to include a battery in the generator/primary pump system? 	




   What does your system architecture look like?

   Are you duplicating a system already flying

   or is this something original?



 

 

   Bob . . .

kenryan

Joined: 20 Oct 2009
Posts: 426

Posted: Tue Jun 21, 2016 11:08 am Post subject: battery question

It was suggested to me by the Rotax dealer in Canada. Like I said, the integrated generator only runs the main fuel pump. There is a 22K capacitor specified. The external alternator powers the main bus and charges the battery. There has been some recent discussion suggesting a need for a battery in the system, but I was not planning one on the generator-fuel pump circuit.



On Tue, Jun 21, 2016 at 10:44 AM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

 	  Quote: 	
		    At 12:09 PM 6/21/2016, you wrote:

  	  Quote: 	
		  I am installing a Rotax 914 which requires an electric fuel pump to run. My electrical system architecture will have the primary pump running directly off the integrated generator. The primary pump will be the ONLY load on the generator. The backup pump will run off the battery bus, connected to the external alternator. My question is, does it make any sense to include a battery in the generator/primary pump system? 	




 Â  What does your system architecture look like?

 Â  Are you duplicating a system already flying

 Â  or is this something original?



 

 

 Â  Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Jun 21, 2016 12:38 pm Post subject: battery question

At 02:03 PM 6/21/2016, you wrote:

  	  Quote: 	
		  It was suggested to me by the Rotax dealer in Canada. Like I said, the integrated generator only runs the main fuel pump. There is a 22K capacitor specified. The external alternator powers the main bus and charges the battery. There has been some recent discussion suggesting a need for a battery in the system, but I was not planning one on the generator-fuel pump circuit. 	


  Giving well considered advice based on the information

  you've supplied is difficult if not fraught with

  risk. We're viewing your system through a 'knothole'.

  

  With that much generation ability, consider Figures Z-13/8

  in the 'Connection.



  http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z13-8T.pdf

 

  Use your external alternator as the MAIN and

  the built in alternator as the STANDBY. Wire

  the main pump to the battery bus, the standby

  pump to the main bus.



  This architecture has been vetted by hundreds of

  builders over the past 20+ years and offers

  very high system reliability with no weight

  penalties over what the Rotax folks might offer.



  Rotax builds pretty good engines but their

  expertise in aircraft electrical systems is

  not well demonstrated.



 

 

   Bob . . .

kenryan

Joined: 20 Oct 2009
Posts: 426

Posted: Tue Jun 21, 2016 12:51 pm Post subject: battery question

Thanks Bob. I'll look at it.



On Tue, Jun 21, 2016 at 12:36 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

 	  Quote: 	
		    At 02:03 PM 6/21/2016, you wrote:

  	  Quote: 	
		  It was suggested to me by the Rotax dealer in Canada. Like I said, the integrated generator only runs the main fuel pump. There is a 22K capacitor specified. The external alternator powers the main bus and charges the battery. There has been some recent discussion suggesting a need for a battery in the system, but I was not planning one on the generator-fuel pump circuit. 	


 Â Giving well considered advice based on the information

 Â you've supplied is difficult if not fraught with

 Â risk. We're viewing your system through a 'knothole'.

 Â 

 Â With that much generation ability, consider Figures Z-13/8

 Â in the 'Connection.



  http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z13-8T.pdf

 

 Â Use your external alternator as the MAIN and

 Â the built in alternator as the STANDBY. Wire

 Â the main pump to the battery bus, the standby

 Â pump to the main bus.



 Â This architecture has been vetted by hundreds of

 Â builders over the past 20+ years and offers

 Â very high system reliability with no weight

 Â penalties over what the Rotax folks might offer.



 Â Rotax builds pretty good engines but their

 Â expertise in aircraft electrical systems is

 Â not well demonstrated.



 

 

 Â  Bob . . .

kenryan

Joined: 20 Oct 2009
Posts: 426

Posted: Tue Jun 21, 2016 1:10 pm Post subject: battery question

Am I correct in thinking that if I wanted to do away with the endurance bus I could eliminate the relay (1N4001) and the switch that energizes it?



On Tue, Jun 21, 2016 at 12:48 PM, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:

 	  Quote: 	
		  Thanks Bob. I'll look at it.



On Tue, Jun 21, 2016 at 12:36 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

 	  Quote: 	
		    At 02:03 PM 6/21/2016, you wrote:

  	  Quote: 	
		  It was suggested to me by the Rotax dealer in Canada. Like I said, the integrated generator only runs the main fuel pump. There is a 22K capacitor specified. The external alternator powers the main bus and charges the battery. There has been some recent discussion suggesting a need for a battery in the system, but I was not planning one on the generator-fuel pump circuit. 	


 Â Giving well considered advice based on the information

 Â you've supplied is difficult if not fraught with

 Â risk. We're viewing your system through a 'knothole'.

 Â 

 Â With that much generation ability, consider Figures Z-13/8

 Â in the 'Connection.



  http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z13-8T.pdf

 

 Â Use your external alternator as the MAIN and

 Â the built in alternator as the STANDBY. Wire

 Â the main pump to the battery bus, the standby

 Â pump to the main bus.



 Â This architecture has been vetted by hundreds of

 Â builders over the past 20+ years and offers

 Â very high system reliability with no weight

 Â penalties over what the Rotax folks might offer.



 Â Rotax builds pretty good engines but their

 Â expertise in aircraft electrical systems is

 Â not well demonstrated.



 

 

 Â  Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Jun 21, 2016 1:21 pm Post subject: battery question

At 04:08 PM 6/21/2016, you wrote:

  	  Quote: 	
		  Am I correct in thinking that if I wanted to do away with the endurance bus I could eliminate the relay (1N4001) and the switch that energizes it? 	


   The endurance bus would be loaded with

   only those goodies you would operate from

   the stand-by alternator . . . generally

   limited to 15-18 amps which is the

   internal alternator's rated output.



   Everything else goes on the Main bus.

   During loss of main alternator, you continue

   flight to airport of intended destination

   with the battery contactor OFF, E-bus

   alternate feed switch ON, S/B alternator

   switch ON.



   When airport is in sight, you now have all

   the battery's reserves available to close

   the battery contactor and operate all the

   goodies for descent and approach to landing.



   The e-bus is an integral component of the

   energy management philosophy on which Z-13/8

   is based.  The big advantage for you is that

   unlike an SD-8 s/b alternator mounted to the

   back of a Lycoming, YOUR s/b alternator is about

   twice that size. You have much larger e-bus

   options for the endurance mode of flight.



 

 

   Bob . . .

kenryan

Joined: 20 Oct 2009
Posts: 426

Posted: Tue Jun 21, 2016 1:37 pm Post subject: battery question

I already have the ability to turn each component on or off with its own switch.Â  Separate ebus with its wiring and relay etc. seem superfluous. 

Sent from my Android. Sorry Steve. On Jun 21, 2016 13:27, "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote: 	  Quote: 	
		    At 04:08 PM 6/21/2016, you wrote:

  	  Quote: 	
		  Am I correct in thinking that if I wanted to do away with the endurance bus I could eliminate the relay (1N4001) and the switch that energizes it? 	


 Â  The endurance bus would be loaded with

 Â  only those goodies you would operate from

 Â  the stand-by alternator . . . generally

 Â  limited to 15-18 amps which is the

 Â  internal alternator's rated output.



 Â  Everything else goes on the Main bus.

 Â  During loss of main alternator, you continue

 Â  flight to airport of intended destination

 Â  with the battery contactor OFF, E-bus

 Â  alternate feed switch ON, S/B alternator

 Â  switch ON.



 Â  When airport is in sight, you now have all

 Â  the battery's reserves available to close

 Â  the battery contactor and operate all the

 Â  goodies for descent and approach to landing.



 Â  The e-bus is an integral component of the

 Â  energy management philosophy on which Z-13/8

 Â  is based.Â  The big advantage for you is that

 Â  unlike an SD-8 s/b alternator mounted to the

 Â  back of a Lycoming, YOUR s/b alternator is about

 Â  twice that size. You have much larger e-bus

 Â  options for the endurance mode of flight.



 

 

 Â  Bob . . .

user9253

Joined: 28 Mar 2008
Posts: 1921
Location: Riley TWP Michigan

Posted: Tue Jun 21, 2016 3:59 pm Post subject: Re: battery question

What advantage does an additional battery offer?

email me at fransew at gmail

_________________
Joe Gores

kenryan

Joined: 20 Oct 2009
Posts: 426

Posted: Tue Jun 21, 2016 4:31 pm Post subject: battery question

I'm not saying that a battery offers any advantages. I'm asking whether or not it is necessary to have a battery in the system. Another poster on this forum breached the idea (just a few days ago) that a battery might be necessary to "smooth" the output. I "think" that idea was debunked, but I'm never quite sure how to interpret some of the responses. In any event, that discussion was about a "failed" battery. I have not seen the idea of battery elimination discussed. I've been reviewing Z-13/8 and it seems to have some advantages but also seems to add unnecessary complications.



On Tue, Jun 21, 2016 at 3:59 PM, user9253 <fransew(at)gmail.com (fransew(at)gmail.com)> wrote:

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

 

 What advantage does an additional battery offer?

 email me at fransew at gmail

 

 --------

 Joe Gores

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=457369#457369

 

 

 

 

 

 

 

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nuckolls.bob(at)aeroelect
Guest

Posted: Tue Jun 21, 2016 4:33 pm Post subject: battery question

At 04:34 PM 6/21/2016, you wrote:



  	  Quote: 	
		  I already have the ability to turn each component on or off with its own switch.Â  Separate ebus with its wiring and relay etc. seem superfluous. 	


  The e-bus is NOT an avionics bus . . . it's

  a plan-b configuration tool for gathering

  a REDUCED electrical load onto an ENDURANCE

  bus. It's a way to do all of your plan-b

  authorship on the ground. When the LV warning

  light comes on, flip 3 switches and trundle

  on to airport of intended destination.



  It's also a dual-source bus that functions

  in the rare event of loss of battery contactor.



  It is powered up from the main bus through

  the normal feed diode . . . main bus up . . .

  e-bus is up.



  Have you done a load analysis to know

  what energy is needed to get into an

  optimized endurance mode? 



 

   Bob . . .

kenryan

Joined: 20 Oct 2009
Posts: 426

Posted: Tue Jun 21, 2016 5:11 pm Post subject: battery question

I don't think it's a big deal to flip a couple of switches if the LV light comes on. I have done a load analysis, but I don't completely understand what you mean by "optimized endurance mode."Â 



The only thing necessary to keep the airplane in the air is one fuel pump, approximately 5 amps. This is a VFR only airplane, so nothing else is really necessary to get home safely.Â 

The EFIS is Dynon with their proprietary backup battery.Â 

If everything is turned on and working, the draw is about 25 amps (peak).



With the system I already planned, the primary fuel pump is driven by the generator in an autonomous system. There isn't even a fuel pump switch in this system. The system consists of generator, regulator, capacitor, fuel pump, inline fuse, momentary contact switch to energize the generator, and the wiring to connect things together.Â 

The auxiliary fuel pump is switched off a battery bus (not really a bus, just a wire from the hot side of the battery relay) with an inline fuse.Â 

Everything else runs off the main bus, which is connected to the external alternator and battery.

If the generator (or regulator) fails, the main fuel pump stops but there is still the battery and the alternator to power the auxiliary fuel pump and keep the engine running.

If the alternator fails, the engine keeps running because the main fuel pump is not affected. The main bus becomes powered by the battery. Depending upon the situation load shedding might be desirable to preserve enough battery power to run the aux fuel pump for landing (normal takeoff and landings use both pumps).Â 

It seems the worst case scenario is the generator failure, as that takes out the main fuel pump and should the auxiliary pump fail, the airplane comes down.

I don't really know what happens if the EarthX ETX36C lithium battery fails. Hopefully the airplane does not burn up in flight.



On Tue, Jun 21, 2016 at 4:32 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

 	  Quote: 	
		    At 04:34 PM 6/21/2016, you wrote:



  	  Quote: 	
		  I already have the ability to turn each component on or off with its own switch.Ã‚Â  Separate ebus with its wiring and relay etc. seem superfluous. 	


 Â The e-bus is NOT an avionics bus . . . it's

 Â a plan-b configuration tool for gathering

 Â a REDUCED electrical load onto an ENDURANCE

 Â bus. It's a way to do all of your plan-b

 Â authorship on the ground. When the LV warning

 Â light comes on, flip 3 switches and trundle

 Â on to airport of intended destination.



 Â It's also a dual-source bus that functions

 Â in the rare event of loss of battery contactor.



 Â It is powered up from the main bus through

 Â the normal feed diode . . . main bus up . . .

 Â e-bus is up.



 Â Have you done a load analysis to know

 Â what energy is needed to get into an

 Â optimized endurance mode? 



 

 Â  Bob . . .

jmjones2000(at)mindspring
Guest

Posted: Tue Jun 21, 2016 6:41 pm Post subject: battery question

Maybe a little off topic, but if anyone is worried about the single battery idea, I installed the EarthX set of jumper wires connecting directly to the battery (pos and neg). They come to the instrument panel and terminate in a socket. It's the install kit that EarthX sells with their Lithium jump pack. Whole kit is less than 1lb. It will work to jumpstart the plane (ask how I know) and it will extend battery life if you loose all alternators on your system. 

The jump pack can't be recharged by plugging it in during flight. Only by plugging it in to the charger that comes with it. It also charges any usb device. 

Justin



On Jun 21, 2016, at 18:32, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

 	  Quote: 	
		    At 04:34 PM 6/21/2016, you wrote:



  	  Quote: 	
		  I already have the ability to turn each component on or off with its own switch.Ã‚  Separate ebus with its wiring and relay etc. seem superfluous. 	


  The e-bus is NOT an avionics bus . . . it's

  a plan-b configuration tool for gathering

  a REDUCED electrical load onto an ENDURANCE

  bus. It's a way to do all of your plan-b

  authorship on the ground. When the LV warning

  light comes on, flip 3 switches and trundle

  on to airport of intended destination.



  It's also a dual-source bus that functions

  in the rare event of loss of battery contactor.



  It is powered up from the main bus through

  the normal feed diode . . . main bus up . . .

  e-bus is up.



  Have you done a load analysis to know

  what energy is needed to get into an

  optimized endurance mode? 



 

   Bob . . .

user9253

Joined: 28 Mar 2008
Posts: 1921
Location: Riley TWP Michigan

Posted: Wed Jun 22, 2016 3:23 am Post subject: Re: battery question

kenryan, Your electrical system sounds perfect to me.  Why change a proven design by adding more weight, cost, time, and complexity?  A backup to a backup is not needed unless someone can offer data showing that the primary fuel pump will perform better or last longer with a battery added to the system.

_________________
Joe Gores

kenryan

Joined: 20 Oct 2009
Posts: 426

Posted: Wed Jun 22, 2016 6:47 am Post subject: battery question

Thanks Joe, that's what I'm thinking too.



On Wed, Jun 22, 2016 at 3:23 AM, user9253 <fransew(at)gmail.com (fransew(at)gmail.com)> wrote:

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

 

 kenryan, Your electrical system sounds perfect to me.Â  Why change a proven design by adding more weight, cost, time, and complexity?Â  A backup to a backup is not needed unless someone can offer data showing that the primary fuel pump will perform better or last longer with a battery added to the system.

 

 --------

 Joe Gores

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=457376#457376

 

 

 

 

 

 

 

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 eferrer" target="_blank">http://forums.matronics.com

 ===========

 WIKI -

 errer" target="_blank">http://wiki.matronics.com

 ===========

 b Site -

 Â  Â  Â  Â  Â  -Matt Dralle, List Admin.

 rel="noreferrer" target="_blank">http://www.matronics.com/contribution

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