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Looking for help finalysing my Cozy's electrical system

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Zoom2136

Joined: 03 Oct 2018
Posts: 7
Location: Montreal

Posted: Sun May 31, 2020 5:48 pm Post subject: Looking for help finalysing my Cozy's electrical system

Hi,



I’ve been following many of the discussions here for the last year or so, while planning the rewiring of my Cozy Mk3. Of particular interest to me was the discussion about electrically dependent engines. Because I purchased such a EFI and EI system (EFII’s System 32), I’ve attempted to design an electrical system that I think would allow for the safe operation of such an aircraft, but I’m no electrical engineer so I may be going down the “I don’t know that this thing can kill me road” with a big grin on my face.



Just so you know, this aircraft will operate in Quebec, Canada, where you can go for more than an hour before reaching the midpoint between airports with nothing to see along the way but lakes and forest. So redundancy is very important, for my peace of mind…. 



FYI, I’ve already purchased the following items for my Cozy:



•	Full EFII System 32 (electronic fuel injection & dual ignition)

•	VPX PRO solid-state breaker box (mostly for non-engine related items)

•	GRT Avionics EIS R66 engine monitor

•	GRT Avionic Hxr EFIS

•	B&C BC460-H 60 amp alternator (main)

•	B&C BC410-H 20-40 amp alternator (aux)

•	B&C BCS206 Lycoming starter

•	B&C LR-3C regulator (x2)



I have a lot of other stuff (electric nose gear, electric air brakes, LED nav, taxi & landing lights, radios, transponder, GPS, etc.), but the aforementioned are the primary systems for which I would greatly appreciate your help. The list of GRT stuff is just to let you know what I have to monitor the system.



OK, so a quick description.



My system is based on the Z-14 diagram.



My objective was to have 2 totally independent power paths for the engine-related components and to share the loads and backup power for avionics and other electrical stuff between the MAIN and AUX alternators and batteries, which could be seen more as SYST 1 and SYST 2, I guess.



System back bone (my v1.04 drawing):



1.	Switched side of MAIN Contactor (B&C S701-1) feeds the VPX which in turn feeds non-engine related electro gizmos (EFIS, EIS, radios, etc.).

2.	Switched side of AUX Contactor (B&C S701-1) feeds the AUX BUS that backs up some of the circuits powered through the VPX and powers some backup electrical stuff (e.g.: GRT EFIS on MAIN/AUX, AVMAPS EFIS on AUX).

3.	MAIN BATTERY feeds the engine bus #1 (EB1) via a 50A (final value TBD) breaker and SPST switch

4.	AUX BATTERY feeds the engine bus #2 (EB2) via a 50A (final value TBD) breaker and SPST switch

5.	CROSSFEED Contactor (B&C S701-2) can be closed if one alternator fails (or for a cold start) as the MAIN, AUX and ENGINE BUSSES subsystem should be 100% independent (except for backup circuits). A green LED indicates if CROSSFEED if closed

6.	VPX will monitor both battery voltage.



Engine, ignition and fuel delivery subsystems (v2.12 (updated) drawing):



Composed of 2 independent engine bus (EB1 & EB2), each powering a subset of components that will keep the engine running on its own.



a.	EB1 bus powers:

i.	the TOP COIL

ii.	Left (#1) ECU

iii.	Main (#1) fuel pump

iv.	IF either [ECU #1] or [ECU #1 and #2] is/are ON, EB1 powers the 

INJECTOR POWER MODULE



b.	EB2 bus powers:

i.	The BOTTOM COIL

ii.	Right (#2) ECU

iii.	Aux (#2) fuel pump

iv.	IF ECU #1 is OFF, EB2 powers the INJECTOR POWER MODULE



* FYI, the injector duty can be handled by either ECU, but only one at any time.



I’ve followed EFII System 32 power wiring schematics (see attached file) logic and breakers/fuses value recommendations, but I will not be using its Bus Manager.

 

My ECU and INJECTOR power and control setup



[updated see v2.12]



My objective was to minimize the number of switches while still being able to isolate stuff if something went wrong. My thinking is that having 2 independent engine buses that can be switched off to take offline components that form a subsystem seems to fit this criterion.



[Updated] Using 1 ACS ACS-510-5 starter key switch (without the start option) controling 1 changeover relay for switching between which ECU handles injector duty and 2 SPST switching power to EB1 and EB2 and , I can switch between 3 conditions using :



A.	EB1 ON only

ECU #1 (ON) / ECU #2 (OFF), TOP COIL (ON) / BOTTOM COIL (OFF) & Injectors duty controlled by the ECU #1. Fuel pumps powered from EB1 and a SPDT switch.

B.	EB2 ON only

ECU #2 (ON) / ECU #1 (OFF), BOTTOM COIL (ON) / TOP COIL (OFF) & Injector duty controlled by the ECU #2. Fuel pumps powered from EB2 and a SPDT switch.

C.	EB1 and EB2 ON

Both ECU (ON), both COILS (ON) & Injectors duty controlled by the ECU #1. Fuel pumps activated via a DPDT switch are MAIN (ON), AUX (AUTO (using a fuel pressure switch)). 



Thank you for your time,



One more thing, FYI, I have a lot of 18 AWG wire, so if some wire seems to be oversized to 18 AWG, it is just that I figure that I can live with the added weight, and use what I have.



Thanks again,



Eric

EFFI Syst 32 suggested electrical diagram.PNG

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C-GEDZ Fuel-Ignition-Oil v2.10.pdf

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C-GEDZ Backbone V1.04.pdf

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_________________
Eric D
Cozy IIIx C-GEDZ

Last edited by Zoom2136 on Wed Jun 03, 2020 5:29 pm; edited 4 times in total

johnbright

Joined: 14 Dec 2011
Posts: 165
Location: Newport News, VA

Posted: Sun May 31, 2020 8:39 pm Post subject: Re: Looking for help finalysing my Cozy's electrical system

Single points of failure:

All four injectors are powered by one reley, wire, and fuse link.

Both pumps are powered thru the same switch.



Questions:

The injectors have fuse links in the harness. Are they sized so they won't pop the one fuse link that feeds all four injectors?

What happens if both injector enable inputs are un-grounded?

Why are there relays for removing power from the coils?

What is the EFII Syst 32 Inj Pwr Module? I would have thought each ECU box has open collector injector drivers inside.

Will the automatic aux pump feature result in a relaxation oscillator? (No pressure, pump on... now we have pressure, pump off, repeat.)

Where are the batteries located?



Thoughts/IMO:

It would be simpler to have separate toggle switches for left and right coil "P-Leads".

It wouild be simpler to have an SPDT switch for injector enable grounds like EFII illustrates but what is the effect if the ground is lost to both injector enables?

EFII shows SPOFs that will stop the engine in Dwg 9 rev 5/19 that you attached.

50A is more than an engine bus requires. I am planning on dual four cylinder SDS EFI+I on O-360 and my information/calculations show:

ECU 0.13A each

Coilpack 1.1A each at cruise

Fuel pump 5.25A each at 45 PSI (Walbro GSL393)

14.5 Ohm injectors 0.32A each at cruise (32% duty cycle, 10 GPH)

I plan to put both SDS EFI+I systems (pri and bak) on one engine bus and the current draw is less than 20A (15A with both pumps and coils running for low altitude; 8.2A with one coil and one pump running in current conservation mode).

I'm planning on an adaptation of Z-101 which is simpler than Z-14 and IMO just as reliable.

It would be simpler and more reliable to have separate toggle switches for the main and aux fuel pumps and eliminate the fuel pressure switch.

The fuel pressure switch is called NO; I would think that means it is open when there is no fuel pressure so the logic is backwards.

You mentioned dwg 1.04 but attached 1.00.

_________________
John Bright, RV-6A, at FWF, O-360
Z-101 single batt dual alt SDS EM-5-F.
john_s_bright@yahoo.com, Newport News, Va
N1921R links

Last edited by johnbright on Tue Jun 02, 2020 10:04 pm; edited 1 time in total

Zoom2136

Joined: 03 Oct 2018
Posts: 7
Location: Montreal

Posted: Mon Jun 01, 2020 7:38 am Post subject: Re: Looking for help finalysing my Cozy's electrical system

Hi, thanks for taking the time to review my diagrams.



 	  johnbright wrote: 	
		  Single points of failure:



All four injectors are powered by one reley, wire, and fuse link. 	




*** The one wire & fuse link is supplied by the manufacturer and is the recomended setup. I added a relay to be able to switch power source between EB1 & EB2 when selecting an ECU (or both). The relay could be replaced by diode protected feed wire, Not sure if this would be safer?



 	  johnbright wrote: 	
		  Both pumps are powered thru the same switch. 	




*** Agreed, but what is the failure mode of a switch? 1) Welded shut contacts? The one pump would always be ON. 2) Worn contacts, then 1 of the 2 pumps should be able? I'm I wrong?



 	  johnbright wrote: 	
		  Questions:

The injectors have fuse links in the harness. Are they sized so they won't pop the one fuse link that feeds all four injectors?

What happens if both injector enable inputs are un-grounded?

Why are there relays for removing power from the coils?

What is the EFII Syst 32 Inj Pwr Module? I would have thought each ECU box has open collector injector drivers inside.

Will the automatic aux pump feature result in a relaxation oscillator? (No pressure, pump on... now we have pressure, pump off, repeat.)

Where are the batteries located? 	




*** Fuse links / Are provided and sized by the manufacturer, so they are sized appropriately.



*** Un-grounded injector enable inputs / Then both ECU will try to drive the injector, not a good thing, but their is no work around that I can see. However, with my setup, the first step to trouble shooting is always using the KEY switch in the BOTH ECU position (normal position), select ECU 1 and MAIN FUEL PUMP, if the situation does not improve, selct ECU 2 and AUX FUEL PUMP.



*** Relays for coils / This is to create 2 independant subset of components that can be isolated along with ECU 1 or ECU 2 using only the KEY switch. So the KEY switch allows to kill either ECU 1 or 2 and all their sub-components in one action "kill ECU 1 & TOP COIL and transfer control of the INJECTORS to ECU2" or "kill ECU 2 & BOTTOM COIL and transfer control of the INJECTORS to ECU 1". This could be done with 2 DPDT switch, 1 switch powering ON at the same time ECU 1 and TOP COIL, and a second switch powering on ECU 2 and BOTTOM COIL. 



*** Automatic pump feature / This one is over my head. I have no clue! That behing said, I will have to check with EFII as the system preset pressure is 35PSI, but I have not seen a minium PSI value.



*** Battery location / In a Cozy, they are typically located on the cabin side of the firewall.



 	  johnbright wrote: 	
		  Thoughts/IMO:

It would be simpler to have separate toggle switches for left and right coil "P-Leads".

It wouild be simpler to have an SPDT switch for injector enable grounds like EFII illustrates but what is the effect if the ground is lost to both injector enables?

I don't know how to have faith in Bus Manager (I know you mentioned you are not using Bus Manager) or EFII in general when they show un-necessary SPOFs that will stop the engine. Ref EFII Dwg 9 rev 5/19 that you attached.

50A is more than an engine bus requires. I am planning on dual four cylinder SDS EFI+I on O-360 and my calculations show:

ECU 0.13A

Coilpack 1.1A at cruise

Fuel pump 5.25A at 45 PSI (Walbro GSL393)

14.5 Ohm injectors 0.32A each at cruise (32% duty cycle, 10 GPH)

I plan to put both EFI+I systems (pri and bak) on one engine bus and the current draw is less than 20A (15A with both pumps and coils running for low altitude; 8.2A with one coil and one pump running in current conservation mode).

I'm planning on an adaptation of Z-101 which is simpler than Z-14 and IMO just as reliable.

It would be simpler and more reliable to have separate toggle switches for the main and aux fuel pumps and eliminate the fuel pressure switch.

The fuel pressure switch is called NO; I would think that means it is open when there is no fuel pressure so the logic is backwards.

You mentioned dwg 1.04 but attached 1.00. 	




*** Simpler to operate / I don't beleive so, the way it is now I have 2 subset of components that can be killed independantly if needed using a simple OFF/ECU 1/ECU 2/BOTH key switch.

*** Low pressure fuel swtich / This model is electrically normally open, So it is the correct one.

*** 50 amp is more than an engine bus requires / Agreed. I just added up the breaker values suggested by EFII, but your values are in line with what I came up with.

*** Z101 - I had the 12e edition book, was not aware of Z101.

*** 1.04 vs 1.00 diagram / Will have to check that one.



Again, thanks a lot for your time,



I'm keeping an open mind regarding all your commnents, so don't interpret anything I said as definitive. Sorry I'm French, can't say it better than this!



Eric

_________________
Eric D
Cozy IIIx C-GEDZ

johnbright

Joined: 14 Dec 2011
Posts: 165
Location: Newport News, VA

Posted: Mon Jun 01, 2020 9:08 am Post subject: Re: Looking for help finalysing my Cozy's electrical system

Schematics in the Aeroelectric Connection book have been revised since the book was assembled. And at least in the case of Z-101 a schematic has been added.

http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/



Some other links to files Bob Nuckolls has online:



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

http://www.aeroelectric.com/Books/Connection/

http://www.aeroelectric.com/Catalog/

http://aeroelectric.com/Mfgr_Data/

http://aeroelectric.com/Pictures/

http://www.aeroelectric.com/PPS/ Z schematic PDFs are in subfolder "Adobe_Architecture_Pdfs"

http://www.aeroelectric.com/Reference_Docs/Accidents/

_________________
John Bright, RV-6A, at FWF, O-360
Z-101 single batt dual alt SDS EM-5-F.
john_s_bright@yahoo.com, Newport News, Va
N1921R links

Zoom2136

Joined: 03 Oct 2018
Posts: 7
Location: Montreal

Posted: Tue Jun 02, 2020 6:38 pm Post subject: Re: Looking for help finalysing my Cozy's electrical system

OK, I revisited one of my previous diagrams and went back to dividing components between EB1 and EB2 instead of controlling them through various relays.



This division will allow me to shut down a subset of components by killing either EB1 (shutting off ECU 1, TOP COIL & MAIN FUEL PUMP) or EB2 (shutting off EC2, BOTTOM COIL, AUX FUEL PUMP).



The injector selection and P-LEAD grounding is still controlled through a standard OFF/1/2/BOTH key switch and a single changeover relay.



I've also changed the power path to the AUX FUEL PUMP. By changing the low pressure switch power source from EB2 to EB1, if the fuel pumps DPDT switch fails, the AUX FUEL PUMP will still be powered through the previously mentioned low pressure switch. That should solve the single point of failure issue of having both fuel pumps powered through one switch,

Diagram v2.11 Fuel - Ignition - Backup Oil - DEB.PNG

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_________________
Eric D
Cozy IIIx C-GEDZ

johnbright

Joined: 14 Dec 2011
Posts: 165
Location: Newport News, VA

Posted: Tue Jun 02, 2020 10:24 pm Post subject: Re: Looking for help finalysing my Cozy's electrical system

Re v1.04 and v2.11 and in light of my experience applying (designed, not implemented) SDS EFI+I to Z-101 (one batt, dual alternator).



Questions:

What is the EFII System 32 Injector Power Module? Is that something EFII supplies? It shows the injectors grounded/always on which of course is not the case.

Does the automatic aux pump feature come from EFII? I was thinking it comes with Bus Manager which you are not using so I was thinking you designed this feature.

Is there a need for powering the injectors select relay from EB1? If EB1 is off, ECU 1 is off.

Is the flyback diode built in to the relay?

What injectors are used? SDS uses 14.5 ohm "saturation" injectors.



IMO:

Removing the injector auto fail over and coil select relays of v2.10 was a good idea. No need to buy, install, preflight, explain and remember functionality, fewer failure points.

The automatic pump feature is not required. No switch SPOF, no diodes, no pressure switch. Run both pumps at low altitude (which is legacy training). If the engine stops at cruise altitude, the crew:

Moves the injectors to the bku ECU.

Turns the bku fuel pump on.

Opens alternate air.

Checks fuel.

Restarts with starter or windmill.

Ignition switch function is confusing because when it's on both you have both coils but injectors are on ECU 1. There's no way to fire both coils and have the injectors on ECU 2 (a good idea in any case and may be required for fine-tuning ECU 2 although EFII seems to say this is not the case). Assuming EB 1 and EB 2 are both powered:

Off - boths coils disabled, injectors will fire from ECU 2

Right - bottom coil disabled, injectors will fire from ECU 1

Left - top coil disabled, injectors will fire from ECU 2

Both - both coils enabled, injectors will fire from ECU 1

Delete key switch and relay, use toggle switches for P lead 1, P lead 2, injector enable (SPDT). Or if you really want the key, use it for ignition only and replace the relay with toggle switch.

Replace 2A fuses with 5A so you stock one less size.

The batteries and the engine are in the back. Power EB 1 and EB 2 with relays in the spirit of FAR 23.1361. The feeds can be unprotected if short or you can use a MIDI 23 or 16 awg fuse link wire on 12 awg feeder.



Notes:

Injectors:

I don't know the awg of the fuse links at the individual injectors or the the one in the common wire but they do nothing (24 awg melts at 29A). A short to ground anywhere will blow the fuses and you will lose all injectors. I don't know how to justify powering all injectors thru one path. Seems likely a three cylinder engine will hold altitude.

The 5A fuse is too small for four injectors. The injectors might run up to 85% duty cycle in normal circumstances which means 3.4A. At 100% they will draw 4A. Better make them 10 A or even 15A.

I plan to use individual 5A fuses, one per injector. This leads Z-14 to an injector bus after the diodes, un-fused short wires from EB1 and EB2 to injector bus. Z-101 shows an engine bus instead.

I have a different unerstanding of switch contacts "normally open" and "normally closed" compared to you. Relay terminal 87a is normally closed, opens when the relay is energized. Edelbrock pressure switch 72213 is normally open, closes with pressure.

Coilpacks:

I assume the coilpacks have integral drivers and their connections to the ECUs (not shown) are logic states.

It looks like EFII uses the same Subaru coils SDS uses. (EFII uses three coils in six cylinder applications, one of which fires top and bottom of cylinders 5 and 6. SDS uses two coils on six-cylinder engines, on top, one bottom.)

I'm taking SDS' advice of separate fuses for each coil, each 10A.

Fuel pumps:

Yes, failure of the DPDT fuel pump switch in such a way as to stop both fuel pumps is highly unlikely. The switch would have to fall apart. I mention it as an SPOF but not the highest priority SPOF (the highest priority SPOF is to power the injectors independently).

It looks like EFII is using the same pumps SDS uses, Walbro GSL393.

I'm taking SDS' advice of separate fuses for each pump, each 15A.

I normally expect the left ECU to be primary. Is that just me?

The main alternator only needs 6 awg, or even the 8 awg shown in Z-101.

The aux alternator only needs 10 awg and its ANL could be 35A.

You could use the physically smaller MIDIs from Littlefuse instead of ANLs. You could also use fuse link wire as shown in Z-101.

Wires to crossfeed contactor and starter can be 4 awg.

Batteries are labeled EXT; I assume you mean ETX.

Battery temp sensors are not normally used with batt in engine or passenger compartment.

The aux alternator field should have a 5A CB versus a fuse because it has crowbar OV protection.



In case it's instructive, my version of Z-101 with SDS EFI+I is one of the PDFs in the Google Drive folder linked from my signature. Also in there is a schematic of the SDS system. SDS uses relays to move the injector minus leads from pri to bak ECU drivers versus the EFII injector driver enable ECU inputs. I gather EFII connects the pri and bak drivers in parallel and disables one or the other internal to the ECUs.

johnbright

Joined: 14 Dec 2011
Posts: 165
Location: Newport News, VA

Posted: Wed Jun 03, 2020 7:09 am Post subject: Re: Looking for help finalysing my Cozy's electrical system

Re v1.04 and v2.11



Hi Eric,



I mis-spoke about switching power to EB 1 and EB 2 with relays to meet FAR 23.1361. You already meet FAR 23.1361 with the two battery contactors.



When I was considering Z-14 for my SDS EFI+I equipped RV-6A, I wanted to be able to kill both battery contactors in a smoke in the cockpit situation and still have the engine running:

This led to an always hot engine bus diode OR'd from both batteries.

If you would like to reference my Z-14, it is called "Electrical Schematic RV-6A with SDS dual EM-5-F rev G" in the Archive folder of my files.

SDS requires coilpack power to be switched whereas EFII has the P-lead input to the ECUs. For FAR 23.1361 you could leave the P-leads unconnected and relay switch coilpack power.

The always hot nature of the engine bus and the items attached to it that are not relay switched presents a danger in service and crash scenarios. With Z-101 the only thing always hot that's remote from the battery is the backup alternator and one could choose to add a relay to it.

_________________
John Bright, RV-6A, at FWF, O-360
Z-101 single batt dual alt SDS EM-5-F.
john_s_bright@yahoo.com, Newport News, Va
N1921R links

prestonkavanagh

Joined: 27 Nov 2018
Posts: 16
Location: Tarpon Springs

Posted: Thu Jun 04, 2020 4:29 pm Post subject: Re: Looking for help finalysing my Cozy's electrical system

John – 



Thanks for sharing the several documents.  I’m building a Cozy IV, and about to start the plumbing and wiring, planning on an SDS system.  This should be darn helpful in thinking through the issues.  Regards,  PK

_________________
PBK3
PA-12, BD-4, RV6a, gliders, Rutan canards

johnbright

Joined: 14 Dec 2011
Posts: 165
Location: Newport News, VA

Posted: Fri Jun 05, 2020 6:41 am Post subject: Re: Looking for help finalysing my Cozy's electrical system

 	  prestonkavanagh wrote: 	
		  John – 



Thanks for sharing the several documents.  I’m building a Cozy IV, and about to start the plumbing and wiring, planning on an SDS system.  This should be darn helpful in thinking through the issues.  Regards,  PK 	




You are welcome Preston. Feel free to contact me with questions or comments.

_________________
John Bright, RV-6A, at FWF, O-360
Z-101 single batt dual alt SDS EM-5-F.
john_s_bright@yahoo.com, Newport News, Va
N1921R links

Zoom2136

Joined: 03 Oct 2018
Posts: 7
Location: Montreal

Posted: Fri Jun 05, 2020 12:43 pm Post subject: Re: Looking for help finalysing my Cozy's electrical system

I'ved moved the discussion to the other thread. Here:



http://forums.matronics.com/viewtopic.php?t=16775540

_________________
Eric D
Cozy IIIx C-GEDZ

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