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nuckolls.bob(at)aeroelect
Guest

Posted: Wed Aug 12, 2020 1:04 pm Post subject: RV10 primary elec sys wiring

Alex,



 You need to move this conversation to the AeroElectric-List.

 I see that you are presently subscribed.



 What kind of engine and ignition system? (your excel spread sheet didn't

 come through).



 Your task is not difficult but there are a lot of questions

 about hardware and manner in which the airplane will be

 used.



 I don't have the time to do consulting on individual projects

 except when the subject matter sorts out details of physics

 and practice of interest to the List as a whole.



 But there's a bunch of folk on the List with more experience

 than I in the fabrication and operation of owner built and

 maintained airplanes who would be glad to join and help

 move your project along. 



 This doesn't mean that I won't participate but with

 all the irons I have in the fire, I need to tailor

 my activities to those where I can help the most.



 Tell us more about your project.



 Bob . . .



 



 At 01:49 PM 8/12/2020, you wrote:

  	  Quote: 	
		  Dear Bob,Â 



 I am frustrated, feeling like I know nothing. The more I read - the more this feeling is insideÂ me.Â 

 Commercial aviationÂ experienceÂ now can't help (



 I have made load analyses, as you advised (attached excel doc) - could you, please, give the direction on the primary electrical system?Â 

 still thinking on how to integrate a small backup battery (what equipmentÂ should it power, as EFIS displays and standby display have their own backup batteries), how many buses to use and determine what equipment must be powered from exact bus...

 attachedÂ list has ELA, sources list and equipment list. ELA will be triple-checked, for sure -Â 

 it was not an easy task to determine load in differentÂ phases without experience, but exciting and, I believe, everythingÂ will be fine!Â 



 My main goal is to create a simple, but redundant and reliable system based on hardware which friendÂ has already purchasedÂ 

 (frustrated regarding alternatorÂ with built-in voltage regulator- as read before in the Book it is not the best option, but will see ...)Â Â 

 Â 

 Could you, please, be so kind to help...?



 Kindest regards,

 Alex

nuckolls.bob(at)aeroelect
Guest

Posted: Wed Aug 12, 2020 1:35 pm Post subject: RV10 primary elec sys wiring

At 04:03 PM 8/12/2020, you wrote:

  	  Quote: 	
		  Bob,Â 



 thanks a lot for advice - i will create topic.Â 

 Great thanks for support!Â 	


 Alex,



 Like I said . . . too many irons in the fire . . . it

 slipped my mind that we'd already opened a List topic

 and I published a suggested starting point for your

 architecture:



 See  https://tinyurl.com/y6ku7lbh



 List your ideas as to which accessories would 

 power from each bus in this drawing?



 



 

 

   Bob . . .

rngurley(at)att.net
Guest

Posted: Fri Aug 14, 2020 10:18 am Post subject: RV10 primary elec sys wiring

Bob –

 

For an RV 10 with a rear battery, I would like a rear ground bus in addition to a firewall ground bus.  Is it OK to run a negative wire from the battery to the rear ground bus and then forward to the firewall ground buss?

 

Thank you

 

Dick

 

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L. Nuckolls, III

Sent: Saturday, July 25, 2020 9:54 PM

To: Alex Ivancheskul <airkbp(at)gmail.com>; aeroelectric-list(at)matronics.com

Subject: Re: RV10 primary elec sys wiring

 

At 09:57 AM 7/23/2020, you wrote:

Good day Dear Mr.Nuckolls, 



First, i really happy that i've met your book and web site with plenty of extra useful information.I am aircraft maintenance engineer (mostly Boeing type rated), have practical and theoretical skills. but realized that need some more theoretical researches for better elec system knowledge.



   Those fundamentals will serve you well in your

   new aviation endeavors. Your sense of craftsmanship

   and knowledge of 'how the other guys do it' will

   be useful.



Recently friend of mine asked me to help with his RV-10 electrical and avionics hookup. Most of works are done except all wiring work. I spent many hours doing research and stuck...we have perhaps unusual config with one regular battery(RG-25XC)with Batteryminder charging kit BM-AIK2A, just one primary alternator Plane Power 99-1012 with built-in voltage regulator (unfortunately) and small cmart backup battery TCW IBBA-12v-6AH. Ignition - Champion slick magnetos (6393 and 6350) , lefthand one with SS1001 booster.



   You don't mention how this airplane will be used.

   Day VFR, Day/Nite VFR, 'hard' IFR, extended flight

   over unfriendly terrain? What avionics are anticipated?

   Which devices will exploit the back-up battery?

Despite I am professional avionic I am really stuck and frustrated in myself...



   You've come to the right place. I've taken the liberty

   of signing you up as a participant on the AeroElectric-List.

   We are a 'members only' consortium of aviation enthusiasts with

   broad range of experience and skills. We strive for elegant

   solutions based on good science.



   When you receive the invitation to join us, just respond in

   the affirmative and you'll be 'plugged in' to one of the

   most comprehensive electrical/avionics communities on the

   'net'.

Could you please, advise where can i find help with backbone elec system

architecture and etc...guys want to fly in couple of months))))



   We're pleased to help. Tell us more about the project.

   At firsts blush, your architecture requirements may

   be exceedingly simple. Stand alone magnetos. Simple

   one battery/one alternator configuration not unlike

   hundreds of thousands of type certificated aircraft

   that have flown successfully for a century. The

   greatest difference will be the lack of an 'avionics

   bus' and associated master switch. That concept was

   hatched with poor understanding of then-brand-new

   solid state avionics. The value of the avionics master

   was limited from the beginning then and has no

   value today.



   Based on what we know now, your shared details may

   prompt further suggestions. I've posted a 'first

   pass on an architecture we're evolving here

   on the AeroElectric-List. It shows an endurance

   bus (common to single alternator designs), battery

   bus and a brown-out booster. You may not need

   any of these things we'll help you figure it out. 



   See: https://tinyurl.com/y6ku7lbh



Thank you again for your great work and support of aviation community!



   You're most welcome my friend . . . it's what we do

   here.



  Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Aug 14, 2020 11:27 am Post subject: RV10 primary elec sys wiring

At 01:13 PM 8/14/2020, you wrote:

  	  Quote: 	
		  Bob –

  

 For an RV 10 with a rear battery, I would like a rear ground bus in addition to a firewall ground bus.  Is it OK to run a negative wire from the battery to the rear ground bus and then forward to the firewall ground buss?

  

 Thank you

  

 Dick 	


   Not necessary. Ground batteries locally to structure



 

  https://tinyurl.com/n9rgrg8



  https://tinyurl.com/y5c8qejs



  https://tinyurl.com/y3chtcmh



   Add some ground studs to any fabricated

   brackets utilized in grounding batteries

   to accommodate aft grounds.



   Install firewall ground bus normally.

   Be sure to included crankcase to thru-

   bolt braided strap or 2AWG welding

   cable.



 



 

   Bob . . .

airknot

Joined: 12 Aug 2020
Posts: 11
Location: Europe

Posted: Mon Aug 17, 2020 3:09 am Post subject: Re: RV10 primary elec sys wiring

Dear Matronics Society!



First - I am extremely happy to meet all of you. 

Guys, hope for your kind help in this complicated task. 

GENERAL CONFIG: IFR flights

Power sources config:

1 - alternator 60 A with internal voltage regulator (Plane Power AL12-EI60 (99-1012))

2 â€“ main battery 24 Ah (Concorde RG-25XC)  

3 â€“ backup smart battery (TCW IBBS-12V-6AH) â€“ max cont load 8 A, intermittent 12 A

Engine: Lycoming IO-540-D4A5

Ignition: standard Champion SLICK MAGNETOs 6393 (LH) and 6350(RH) plus SlickStart module S1001 for one magneto(left) for better start. Keyed ignition switch â€“ ACS A-510-2K.

Avionics â€“ Dynon SkyView HDX complex with 2 monitors (+2 backup batteries for displays) and respective subsystems, except comm.

Communication â€“ Garmin GMA245 with GTR 225A

Backup navigation - Garmin G5 system (+ backup battery). 

I am looking for reliable and simple enough systemâ€¦



Bob was extremely kind to me and helped with initial idea of Primary Electric system for RV-10. 

Wiring: https://drive.google.com/file/d/1lbioIrf2NMAUnkgLyg7kzthyvVueMHyV/view?usp=sharing



I have done ELA but found that with 60A alternator i have load that exceeds alt capacity (about 65 A total current draw in max config, that is practically unrealistic situation, but ...). So, now i will double-check ELA, and then will think what to do...



Here is ELA with power sources assessment and List of equipment:

https://drive.google.com/file/d/1KQJFOoFCRKHqWNgRtfG3JbY6XyPKGQ0d/view?usp=sharing



Regarding aux battery - we will use TCW IBBS-12V-6Ah, that can continuously supply 8 Amps when sensing main bus (or another bus, depending on Primary elec system logic) voltage drop below 11 VDC. 

My idea was to create Essential bus to power from this TCW backup battery in case of emergency. 



Quote from TCW Tech Support letter regarding backup battery:

The pass-thru pins are an input that you connect to the main bus. They bring power into the IBBS which is automatically passed through to the outputs. During normal operation, the power from the aircraft bus comes into pins 6,7,8 and is passed out to pins 12-15, this allows the equipment connected to pins 12-15 operate normally. Then if there is a condition on the main bus where the voltage falls below 11 volts, the IBBD internal battery is connected to pins 12-15 to run the essential equipment. No power is back fed to the main bus.



If someone has experience in such smart battery utilization - please, share, itâ€™s very interestingâ€¦



I am kindly asking for help and any kind of assistance and guidance for Primary Electrical System architecture calculations and building. Without you at this stage I do not see the way to successfully build RV10..

toaster73(at)embarqmail.c
Guest

Posted: Mon Aug 17, 2020 7:56 am Post subject: RV10 primary elec sys wiring

There are some nice schematics for the RV-14 or RV-12 that certainly can help you visualize what you may want for the RV-10. GO to this link:

https://www.vansaircraft.com/downloads/

-Chris



--

ceengland7(at)gmail.com
Guest

Posted: Mon Aug 17, 2020 8:42 am Post subject: RV10 primary elec sys wiring

On Mon, Aug 17, 2020 at 6:17 AM airknot <airkbp(at)gmail.com (airkbp(at)gmail.com)> wrote:



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

 

 Dear Matronics Society!

 

 First - I am extremely happy to meet all of you. 

 Guys, hope for your kind help in this complicated task. 

 GENERAL CONFIG: IFR flights

 Power sources config:

 1 - alternator 60 A with internal voltage regulator (Plane Power AL12-EI60 (99-1012))

 2 â€“ main battery 24 Ah (Concorde RG-25XC)Â  

 3 â€“ backup smart battery (TCW IBBS-12V-6AH) â€“ max cont load 8 A, intermittent 12 A

 Engine: Lycoming IO-540-D4A5

 Ignition: standard Champion SLICK MAGNETOs 6393 (LH) and 6350(RH) plus SlickStart module S1001 for one magneto(left) for better start. Keyed ignition switch â€“ ACS A-510-2K.

 Avionics â€“ Dynon SkyView HDX complex with 2 monitors (+2 backup batteries for displays) and respective subsystems, except comm.

 Communication â€“ Garmin GMA245 with GTR 225A

 Backup navigation - Garmin G5 system (+ backup battery). 

 I am looking for reliable and simple enough systemâ€¦

 

 Bob was extremely kind to me and helped with initial idea of Primary Electric system for RV-10. 

 Wiring: https://drive.google.com/file/d/1lbioIrf2NMAUnkgLyg7kzthyvVueMHyV/view?usp=sharing

 

 I have done ELA but found that with 60A alternator i have load that exceeds alt capacity (about 65 A total current draw in max config, that is practically unrealistic situation, but ...). So, now i will double-check ELA, and then will think what to do...

 

 Here is ELA with power sources assessment and List of equipment:

 https://drive.google.com/file/d/1lbioIrf2NMAUnkgLyg7kzthyvVueMHyV/view?usp=sharing

 

 Regarding aux battery - we will use TCW IBBS-12V-6Ah, that can continuously supply 8 Amps when sensing main bus (or another bus, depending on Primary elec system logic) voltage drop below 11 VDC. 

 My idea was to create Essential bus to power from this TCW backup battery in case of emergency. 

 

 Quote from TCW Tech Support letter regarding backup battery:

 The pass-thru pins are an input that you connect to the main bus. They bring power into the IBBS which is automatically passed through to the outputs. During normal operation, the power from the aircraft bus comes into pins 6,7,8 and is passed out to pins 12-15, this allows the equipment connected to pins 12-15 operate normally. Then if there is a condition on the main bus where the voltage falls below 11 volts, the IBBD internal battery is connected to pins 12-15 to run the essential equipment. No power is back fed to the main bus.

 

 If someone has experience in such smart battery utilization - please, share, itâ€™s very interestingâ€¦

 

 I am kindly asking for help and any kind of assistance and guidance for Primary Electrical System architecture calculations and building. Without you at this stage I do not see the way to successfully build RV10..

 



	
What's missing from your loads list above?Â I only see about 20A, absolutely worst case, in that list (unless that Dynon stuff is hideously inefficient). Have you done a spreadsheet, or even just a list, with every load item with columns showing continuous and peak loads for each device,   and if applicable, an intermittent duty column? For example, the Slickstart, and flaps, would be intermittent duty, & need not be part of the continuous load calcs. Comm would have some very low consumption (likely under an amp) except when transmitting. etc etc

Be aware that many (most?) devices spec a circuit protection device that's a lot larger than continuous draw, and somewhat larger than even peak inrush current. In some cases, you might need to actually power up the device to determine its actual continuous & peak draw; some mfgrs don't bother to include that data.

Charlie

airknot

Joined: 12 Aug 2020
Posts: 11
Location: Europe

Posted: Mon Aug 17, 2020 11:49 am Post subject: Re: RV10 primary elec sys wiring

 	  toaster73(at)embarqmail.c wrote: 	
		  There are some nice schematics for the RV-14 or RV-12 that certainly can help you visualize what you may want for the RV-10. GO to this link:

https://www.vansaircraft.com/downloads/

-Chris



-- 	




Thank you, Chris, those wiring schemes are great, but unfortunately they use plenty of some Power Circuit Boards (perheps supplied by VANS with kits).. but plan to use some elemets in avionics hookup

airknot

Joined: 12 Aug 2020
Posts: 11
Location: Europe

Posted: Mon Aug 17, 2020 11:58 am Post subject: Re: RV10 primary elec sys wiring

[/quote]What's missing from your loads list above?Â I only see about 20A, absolutely worst case, in that list (unless that Dynon stuff is hideously inefficient). Have you done a spreadsheet, or even just a list, with every load item with columns showing continuous and peak loads for each device,   and if applicable, an intermittent duty column? For example, the Slickstart, and flaps, would be intermittent duty, & need not be part of the continuous load calcs. Comm would have some very low consumption (likely under an amp) except when transmitting. etc etc

Be aware that many (most?) devices spec a circuit protection device that's a lot larger than continuous draw, and somewhat larger than even peak inrush current. In some cases, you might need to actually power up the device to determine its actual continuous & peak draw; some mfgrs don't bother to include that data.

Charlie[/quote]



Charlie, I have made separate ELA doc, perheps it is some problems with viewing. now it has 2 main columns - "Typical" and "Max" load. PLease, have a quick look: 

https://drive.google.com/file/d/19XBHeM0oGqIDpQcepn1XrqFzVvEpWZq6/view?usp=sharing

ceengland7(at)gmail.com
Guest

Posted: Mon Aug 17, 2020 12:29 pm Post subject: RV10 primary elec sys wiring

On 8/17/2020 2:58 PM, airknot wrote:

 	  Quote: 	
		   



 	
What's missing from your loads list above?Ã‚Â I only see about 20A, absolutely worst case, in that list (unless that Dynon stuff is hideously inefficient). Have you done a spreadsheet, or even just a list, with every load item with columns showing continuous and peak loads for each device,   and if applicable, an intermittent duty column? For example, the Slickstart, and flaps, would be intermittent duty, & need not be part of the continuous load calcs. Comm would have some very low consumption (likely under an amp) except when transmitting. etc etc

 Be aware that many (most?) devices spec a circuit protection device that's a lot larger than continuous draw, and somewhat larger than even peak inrush current. In some cases, you might need to actually power up the device to determine its actual continuous & peak draw; some mfgrs don't bother to include that data.

 Charlie[/quote]



 Charlie, I have made separate ELA doc, perheps it is some problems with viewing. now it has 2 main columns - "Typical" and "Max" load. PLease, have a quick look:

 https://drive.google.com/file/d/19XBHeM0oGqIDpQcepn1XrqFzVvEpWZq6/view?usp=sharing




[/quote]

Google says we need permission to see it; sent the request.



Charlie



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user9253

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

Posted: Mon Aug 17, 2020 3:27 pm Post subject: Re: RV10 primary elec sys wiring

Nobody can access google drive documents without the owner's permission.

_________________
Joe Gores

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Aug 17, 2020 5:46 pm Post subject: RV10 primary elec sys wiring

 	  Quote: 	
		   

  My idea was to create Essential bus to power from this TCW backup battery in case of emergency. 

  	


   Thoughtfully crafted electrical systems do not suffer

   emergencies . . .



 

 

   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Aug 17, 2020 5:46 pm Post subject: RV10 primary elec sys wiring

 	  Quote: 	
		   

  3 – backup smart battery (TCW IBBS-12V-6AH) – max cont loadoad 8 A, intermittent 12 A

  Engine: Lycoming IO-540-D4A5 	
 

   With that engine, why are you including a backup

   battery?  A 8-10A standby alternator on a vacuum

   pump pad offers UNLIMITED endurance with about

   a 4 pound penalty. I go out of my way to avoid

   adding batteries to a design over and above

   those normally expected to start engines and

   back up the primary alternator.



   Do you not PLAN to conduct periodic airworthiness

   checks on the main battery?



 

   Bob . . .

airknot

Joined: 12 Aug 2020
Posts: 11
Location: Europe

Posted: Mon Aug 17, 2020 10:58 pm Post subject: Re: RV10 primary elec sys wiring

[/quote]

Google says we need permission to see it; sent the request.



Charlie

My apologies - i was sure it is accessable for averyone with the link. 

I have double-checked and gave rights to edit: 

ELA - https://drive.google.com/file/d/19XBHeM0oGqIDpQcepn1XrqFzVvEpWZq6/view?usp=sharing



Equipment list, source analisys 

https://drive.google.com/file/d/1KQJFOoFCRKHqWNgRtfG3JbY6XyPKGQ0d/view?usp=sharing



thank you

Alex

airknot

Joined: 12 Aug 2020
Posts: 11
Location: Europe

Posted: Mon Aug 17, 2020 11:00 pm Post subject: Re: RV10 primary elec sys wiring

[/quote]

   Thoughtfully crafted electrical systems do not suffer

   emergencies . . .

  

   Bob . . .[/quote]



I mean loss of primary alternator



Alex

airknot

Joined: 12 Aug 2020
Posts: 11
Location: Europe

Posted: Mon Aug 17, 2020 11:43 pm Post subject: Re: RV10 primary elec sys wiring

 	  nuckolls.bob(at)aeroelect wrote: 	
		   	  Quote: 	
		   

  3 ï¿½ backup smart battery (TCW IBBS-12V-6AH) ï¿½ max cont loadoad 8 A, intermittent 12 A

  Engine: Lycoming IO-540-D4A5 	
 

   With that engine, why are you including a backup

   battery?  A 8-10A standby alternator on a vacuum

   pump pad offers UNLIMITED endurance with about

   a 4 pound penalty. I go out of my way to avoid

   adding batteries to a design over and above

   those normally expected to start engines and

   back up the primary alternator.



   Do you not PLAN to conduct periodic airworthiness

   checks on the main battery?



 

   Bob . . . 	




I feel the same, even more - i prefer independent buses which a powered from different power sources plus 2 batteries. as commercial airplanes constructed... 

but, unfortunately, I was asked to help built Airplane with equipment already purchased...of course I can ask for changes ..



Engine is electrically independent - 

and my idea was 2 or 3 buses, to construct reliable, redundant but simple system using all I have: 

-Main bus powered from alternator

-Battery bus (so called switched hot battery bus - to avoid battery drain in case of always hot battery bus), but it have to be powered not from battery under normal conditions - so only main bus available  

-Essential bus that might be normally powered from the Main bus (thru IBBS battery) and in case of main bus power loss - power from IBBS baterry itself.

Initial idea was to power VHF transciver with its audio control panel. 



Another point is to protect equipment during engine start:

For engine start we need 1 Skyview monitor with its periphery operating

Top important question - battery maintenance. 

Scheduled servicing will be performed - we will install BatteryMInder charger for Main battery and will charge IBBS with its charger (separate unit recommended by TCW).



Due to lack of time - guys want fly asap  - we will do not install Ground power subsystem now, but for sure will schedule this upgrade in winter time. 



Alex

user9253

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

Posted: Tue Aug 18, 2020 3:26 am Post subject: Re: RV10 primary elec sys wiring

 	  Quote: 	
		  Another point is to protect equipment during engine start 	


Absolutely NO equipment needs to be protected during engine start.

There is no such thing as voltage spikes during starting. That is an old wive's tale.

Are you going to believe rumors based on 1950's technology or Bob N. who has written the book on aircraft electrical systems?

Read the following:



http://forums.matronics.com/viewtopic.php?t=16757246&sid=74d855944e77ced507a5bb87d7f9a72f



Avionics Master Switches: Really Necessary?

http://www.aeroelectric.com/articles/avmaster.pdf

_________________
Joe Gores

user9253

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

Posted: Tue Aug 18, 2020 3:37 am Post subject: Re: RV10 primary elec sys wiring

 	  Quote: 	
		  Essential bus that might be normally powered from the Main bus

 (thru IBBS battery) and in case of main bus power loss - power from IBBS baterry itself. 	


I do not like the fact that the output of the IBBS battery is protected by one

10 amp fuse.  If that fuse blows, everything down steam loses power.

I would not power an essential bus through that backup battery.

The cure is worse than the disease.

_________________
Joe Gores

airknot

Joined: 12 Aug 2020
Posts: 11
Location: Europe

Posted: Tue Aug 18, 2020 3:43 am Post subject: Re: RV10 primary elec sys wiring

 	  user9253 wrote: 	
		   	  Quote: 	
		  Another point is to protect equipment during engine start 	


Absolutely NO equipment needs to be protected during engine start.

There is no such thing as voltage spikes during starting. That is an old wive's tale.

Are you going to believe rumors based on 1950's technology or Bob N. who has written the book on aircraft electrical systems?

Read the following:



http://forums.matronics.com/viewtopic.php?t=16757246&sid=74d855944e77ced507a5bb87d7f9a72f



Avionics Master Switches: Really Necessary?

http://www.aeroelectric.com/articles/avmaster.pdf 	


Agree, thank you. i wrote silly thing. Bob told that Avionics switch is unnecessary  nowadays. 

 just think about the most wise and safest way of using equipment available.

ceengland7(at)gmail.com
Guest

Posted: Tue Aug 18, 2020 8:02 am Post subject: RV10 primary elec sys wiring

On 8/18/2020 1:58 AM, airknot wrote:

 	  Quote: 	
		   



 	


 Google says we need permission to see it; sent the request.



 Charlie

 My apologies - i was sure it is accessable for averyone with the link.

 I have double-checked and gave rights to edit:

 ELA - https://drive.google.com/file/d/19XBHeM0oGqIDpQcepn1XrqFzVvEpWZq6/view?usp=sharing



 Equipment list, source analisys

 https://drive.google.com/file/d/1KQJFOoFCRKHqWNgRtfG3JbY6XyPKGQ0d/view?usp=sharing



 thank you

 Alex



OK, got it. 1st thing I noticed is that you didn't totalize current for 
[/quote]

the various phases of flight. Even without looking there, your 'typical' 

consumption for everything is only 36 A. I'd look at cruise, with pitot 

heat and boost pump included for worst case numbers. Re-examine what 

you've included for each phase of flight. ex: Looks like you show 1 A 

for the flap motor, for all phases of flight. Also, look carefully at 

recommended circuit protection values for each device. ex: Even though 

the flap motor may only consume 5 A, IIRC, the docs for it recommend 

closer to 15 A for circuit protection due to startup surge.



I suspect that the number for the boost pump number is a bit low. The 

automotive injection pumps typically used in a/c boost pumps typically 

draw a *minimum* of around 4.5A; most will draw closer to 6A. That draw 

doesn't really change with engine power, since they pump the same 

quantity of fuel at the same pressure, regardless of flow to the engine 

(excess is bypassed back to the inlet). The Walbro pumps (not the one 

used by AFP) recommend a 20A circuit protection, due to startup surge 

current.



I didn't do a line-by-line analysis, so you can probably find more power 

savings.



Charlie



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