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Z101 in an RV-10
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Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Sun Sep 05, 2021 12:48 pm Post subject: Z101 in an RV-10

Agreed, however, in most cases it is to deal with two electrically 

dependent ignition systems, and/or an essential bus for avionics. I 

don't believe the case of electrically dependent fuel system has come 

up, at least not recently.

Given your engine needs air, spark and fuel vapors, do you really want 

fuel and spark to be dependent on the electrical system?

With the fuel system you both have to have the controllers powered and 

both fuel pumps powered, and a means to cross feed power to them.

I'm more comfortable with a plane set up so that if there is any 

electrical problem I can just shut off the master and get to nearest 

suitable airport without needing electrics. Can only recall one time in 

47 years of flying that I needed to do that, but was comforting to be 

able to do. Just as limiting power to just an essential bus expands your 

options to deal with situation.

Somewhat overlooked in the discussion is that the aircraft is to be 

based in Canada, and there are times when the temperatures don't allow 

work on an electrical system (ever pulled a battery at -40?) and 

locations where spare parts might take a fair amount of time and money 

to obtain. Likely remoteness and extreme temps can greatly influence 

risks and your choices.

Kelly



On 9/5/2021 10:55 AM, Ken Ryan wrote:

 	  Quote: 	
		   It seems to me that the issue of a reliable source of power has been 

 confronted and fully addressed in Bob's work.

 

 "I think the real analysis is that you need two separate power sources

 for the fuel injection and the ignition."

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

johnbright

Joined: 14 Dec 2011
Posts: 166
Location: Newport News, VA

Posted: Mon Sep 06, 2021 4:29 pm Post subject: Re: Z101 in an RV-10

Some thoughts.



“… (low) chance of dual alternator failure…”



I plan to fly periodically with the main alternator off to stress test the backup alternator in addition to a preflight functional check.



Note the backup alternator has a shear coupling with a 500 hour/5 year recommended replacement interval per Vic Syracuse, Tempest says 6 years.

“… second alternators are 20A at most…“



The B&C 410 and 425 put out 29 and the 462 32A at 2300 RPM on a Lycoming. At 2700 RPM it’s 32 and 35A respectively. Main advantage of 462 is more current at low RPM, ref spec sheets.

=============



Z101 supports fire-the-cockpit-master-off-engine-keeps-running if you fly with the engine bus alternate feed on. And master relay failure is benign in flight and discoverable at preflight.



I plan to fly with the engine bus alternate feed normally on but periodically off in order to stress test its diode feed path from the main bus.



You can easily add a 2nd stud at the opposite end of a Bussmann 15600 series fuse block to make the engine bus feeds from the battery and from the main bus separate, eliminates that stud as an SPOF.



RV-6A with SDS EFI+I and Z101 as a template, not flying yet.

_________________
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

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Sep 07, 2021 2:38 pm Post subject: Z101 in an RV-10

 	  Quote: 	
		  In the RV-10, the battery and battery contactor are located in the tailcone.

 Looking at the schematic, I will need to run a large conductor (probably 2AWG)

 forward from the contactor to the starter. 	


   4AWG is fine



  	  Quote: 	
		  My concern is that the "fat wire tie point" for the battery bus, aux bus,

 and engine bus will need a second large conductor run forward (my aux and

 engine busses have decent loads due to IFR and EFII equipment). This

 seems like it will add considerable weight... 	


   "second large conductor", "decent loads", "considerable weight"

   are not quantified. The best decisions are made with calculated

   data. What are the loads on conductors to those busses from

   their aux power relays?



  	  Quote: 	
		  The only solution I can imagine would be to leave the battery in the tail

 and move the battery contactor forward to the firewall. 	


    No. Battery contactors go next to batteries as do

    the aux power relays. See the (*) symbol on the

    upstream conductors?



  	  Quote: 	
		  This would leave a long length of unprotected wire 	


    Not recommended nor necessary



  	  Quote: 	
		  This might become more clear as I start to actually run wires but for now it seems less than ideal. Thoughts? 	


    You have two aux bus feeders. I suspect 10AWG would be

    quite sufficient . . . but do the numbers. What are the

    loads and how long are they?



    10AWG is on the order of .04 lb/ft so two 8' runs

    would add about 10 ounces. An 8' run of 2AWG is

    right at 2 pounds; 4AWG is about 1.2 pounds. So

    down-size to 4AWG and add two runs of 10AWG and

    it's about a wash.



    Your exact results may vary . . .



 

   Bob . . .



   Un impeachable logic: George Carlin asked, "If black boxes

   survive crashes, why don't they make the whole airplane

   out of that stuff?"

Watzlavick

Joined: 06 Sep 2021
Posts: 3
Location: Texas

Posted: Tue Sep 07, 2021 6:05 pm Post subject: Re: Z101 in an RV-10

I'm also considering Z101 for my RV-10 but I'm concerned about the always hot B-lead from the aux alternator to the rear mounted battery in a crash situation.  I see 3 options:  1) add another contactor between the aux alternator and battery, 2) use Z-12 instead, or 3) don't fret about the hot B-lead.  I've searched through the archives quite a bit and there doesn't seem to be a good consensus whether having an always hot lead with a rear battery is a really bad idea or not.



A different question if I may - With Z-101 and the aux alt off, if the battery contactor fails open (unlikely I know) but the main alternator is still running, the battery would then charge via the diode between the main and Endurance bus assuming that relay is closed.  Depending on the battery charge state, It seems possible the charge current could blow the fuseable link between the battery and Endurance bus, taking the battery off line.  Seems like a diode is needed between the Endurance bus and battery to prevent that.  Or is the battery charge current sufficiently limited?



-Robert

Ceengland

Joined: 11 Oct 2020
Posts: 391
Location: MS

Posted: Tue Sep 07, 2021 6:44 pm Post subject: Z101 in an RV-10

On 9/7/2021 9:05 PM, Watzlavick wrote:

 	  Quote: 	
		   



 I'm also considering Z101 for my RV-10 but I'm concerned about the always hot B-lead from the aux alternator to the rear mounted battery in a crash situation.  I see 3 options:  1) add another contactor between the aux alternator and battery, 2) use Z-12 instead, or 3) don't fret about the hot B-lead.  I've searched through the archives quite a bit and there doesn't seem to be a good consensus whether having an always hot lead with a rear battery is a really bad idea or not.



 A different question if I may - With Z-101 and the aux alt off, if the battery contactor fails open (unlikely I know) but the main alternator is still running, the battery would then charge via the diode between the main and Endurance bus assuming that relay is closed.  Depending on the battery charge state, It seems possible the charge current could blow the fuseable link between the battery and Endurance bus, taking the battery off line.  Seems like a diode is needed between the Endurance bus and battery to prevent that.  Or is the battery charge current sufficiently limited?



 -Robert

The 10ga aux B lead is protected by the 14ga fusible link. I didn't try 
	


to read the Z101B notes, but I'd assume that wire sizes for the aux alt 

assume a smaller alternator (typical B&C, etc vac pad mounted alternator 

(at) ~30A max). The 10ga wire with 14ga fusible link should work for 30A.



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_________________
Charlie

Watzlavick

Joined: 06 Sep 2021
Posts: 3
Location: Texas

Posted: Tue Sep 07, 2021 6:50 pm Post subject: Re: Z101 in an RV-10

Good point - after I sent the email, I started looking at charge currents and you're right - it's limited by the alternator output.  I guess you could call the lack of a diode there a feature in that it allows the battery to be charged via an alternate path.  It also seems like it would provide some load stabilization for the alternator.



-Robert

A Lumley

Joined: 12 May 2021
Posts: 10
Location: Ontario, Canada

Posted: Wed Sep 08, 2021 5:00 am Post subject: Re: Z101 in an RV-10

 	  Quote: 	
		  "second large conductor", "decent loads", "considerable weight"

   are not quantified. The best decisions are made with calculated

   data. What are the loads on conductors to those busses from

   their aux power relays? 	




My engine bus currently has loads of about 27 Amps with both fuel pumps and coils operating. The aux bus is loaded to about 19 amps. Currently I am planning a 10AWG feeder into each bus from their respective relays and a 6AWG second conductor forward from the battery. These are conservative but I figure they'll be important connections should I ever need them so would prefer them a little larger.



I've attached my current schematic which hopefully makes things clearer.

RV-10 Schematic 1.0.pdf

Description:

Download

Filename:

RV-10 Schematic 1.0.pdf

Filesize:

1.97 MB

Downloaded:

353 Time(s)

Watzlavick

Joined: 06 Sep 2021
Posts: 3
Location: Texas

Posted: Wed Sep 08, 2021 5:52 am Post subject: Re: Z101 in an RV-10

Thanks for posting the schematic.  So appropriate sizing of the aux bus wires handles my second concern which is charging the battery through the main to aux diode.  What are your thoughts about the always hot wire between the battery and aux alt?  Without an additional contactor, there's no way to make the wire cold if needed.

-Robert

A Lumley

Joined: 12 May 2021
Posts: 10
Location: Ontario, Canada

Posted: Wed Sep 08, 2021 6:08 am Post subject: Re: Z101 in an RV-10

I don't see a problem with that segment. The portion forward of the firewall will be protected by an ANL fuse. I don't think there's a way around having a smaller always hot wire that runs from the battery to the fat wire tie point which I plan to mount on the cockpit side of the firewall. By adding another contactor you're just adding another component and if I ever need to fly on battery alone, I don't want the additional current draw of an extra contactor.



I'm planning on using an EarthX battery so I figure if for some reason that hot battery cable was shorted to ground, at least the battery BMS would disconnect the battery hopefully preventing a fire. Although I think the best protection is to run that wire carefully with lots of mechanical protection in its own conduit or similar.

Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Wed Sep 08, 2021 6:13 am Post subject: Z101 in an RV-10

You might be interested that my entire load for Day VFR in my RV-10 is 

13 amps, with 2 EFIS, IFR GPS/nav/com, 2nd com, transponder, strobes, 

etc. Of course engine is zero unless I run the boost pump at about 8 

amps. I don't get above 30 amps unless I am running landing lights and 

pitot heat.

How big a primary alternator are you planning?

On 9/8/2021 6:00 AM, A Lumley wrote:

 	  Quote: 	

> "second large conductor", "decent loads", "considerable weight"

>     are not quantified. The best decisions are made with calculated

>     data. What are the loads on conductors to those busses from

>     their aux power relays?

 My engine bus currently has loads of about 27 Amps with both fuel pumps and coils operating. The aux bus is loaded to about 19 amps. Currently I am planning a 10AWG feeder into each bus from their respective relays and a 6AWG second conductor forward from the battery. These are conservative but I figure they'll be important connections should I ever need them so would prefer them a little larger.

 I've attached my current schematic which hopefully makes things clearer.

 Read this topic online here:

 http://forums.matronics.com/viewtopic.php?p=503092#503092

 Attachments:

 http://forums.matronics.com//files/rv_10_schematic_10_972.pdf

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

A Lumley

Joined: 12 May 2021
Posts: 10
Location: Ontario, Canada

Posted: Wed Sep 08, 2021 6:22 am Post subject: Re: Z101 in an RV-10

My calculations are definitely on the conservative side. I distributed the loads such that I could fly on the Aux bus and Engine busses alone in IMC if I were to lose the primary alternator or otherwise had to shut down the main bus.



My aux bus looks like this:



Pitot Heat (7 Amps)

GTN 750 Xi GPS/NAV/COM (3.45 Amps)

G3X PFD 1 (2 Amps)

3x GSA28 Autopilot Servos (1.5 Amps)

3x Trim Servos (1.5 Amps)

GMA245 Audio Panel (1 Amp)

GTX 45R Transponder (1 Amp)

GEA24 (0.43 Amps)

#1 ADAHRS (0.2 Amps)

G5 Backup (0.2 Amps)

GMC 507 Autopilot (0.2 Amps)

#1 GMU11 (0.1 Amps)

Annunciator Panel (0.1 Amps)

Total: 18.7 Amps



Ideally I could quickly leave IMC and drop the pitot heat.



I expect in real life the engine will only draw about 14 Amps at cruise with only one pump running but I wanted to design things for worst case.



I'm planning a 60A primary alternator.

Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Wed Sep 08, 2021 7:20 am Post subject: Z101 in an RV-10

You don't need 3 trim servos. The pitch trim is all you need. You may 

want aileron, but really neither rudder nor aileron is needed with an 

autopilot. Once you get rudder fixed trim to fly straight and level in 

trim, the forces for climb and descent are minimal. Especially since you 

are planning on a yaw servo. Given your loads, you might want to explore 

a 70 amp alternator..not a huge difference in cost, lets it operate on 

lower percent of full load. Are you figuring nav lights and strobes in 

your total? Probably under 3 amps if LED.



On 9/8/2021 7:22 AM, A Lumley wrote:

 	  Quote: 	
		   

 

 My calculations are definitely on the conservative side. I distributed the loads such that I could fly on the Aux bus and Engine busses alone in IMC if I were to lose the primary alternator or otherwise had to shut down the main bus.

 

 My aux bus looks like this:

 

 Pitot Heat (7 Amps)

 GTN 750 Xi GPS/NAV/COM (3.45 Amps)

 G3X PFD 1 (2 Amps)

 3x GSA28 Autopilot Servos (1.5 Amps)

 3x Trim Servos (1.5 Amps)

 GMA245 Audio Panel (1 Amp)

 GTX 45R Transponder (1 Amp)

 GEA24 (0.43 Amps)

 #1 ADAHRS (0.2 Amps)

 G5 Backup (0.2 Amps)

 GMC 507 Autopilot (0.2 Amps)

 #1 GMU11 (0.1 Amps)

 Annunciator Panel (0.1 Amps)

 Total: 18.7 Amps

 

 

 Ideally I could quickly leave the IMC and drop the pitot heat.

 

 I expect in real life the engine will only draw about 14 Amps at cruise with only one pump running but I wanted to design things for most case.

 

 I'm planning a 60A primary alternator.

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=503096#503096

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

Ceengland

Joined: 11 Oct 2020
Posts: 391
Location: MS

Posted: Thu Sep 09, 2021 1:11 pm Post subject: Z101 in an RV-10

Also, trim load is *very* intermittent (extremely low total energy use), 

and given that you can run one on a 9V transistor radio (remember 

those?) battery, I'd want to verify even the .5A per servo number.

Same for comm; much lower continuous than when transmitting.

And I can't imagine me running both fuel pumps at once for any reason, 

except TO/landing. If pressure drops, my technique would be switching 

pumps rather than adding one.

On 9/8/2021 10:19 AM, Kelly McMullen wrote:

 	  Quote: 	

 <kellym(at)aviating.com>

 You don't need 3 trim servos. The pitch trim is all you need. You may 

 want aileron, but really neither rudder nor aileron is needed with an 

 autopilot. Once you get rudder fixed trim to fly straight and level in 

 trim, the forces for climb and descent are minimal. Especially since 

 you are planning on a yaw servo. Given your loads, you might want to 

 explore a 70 amp alternator..not a huge difference in cost, lets it 

 operate on lower percent of full load. Are you figuring nav lights and 

 strobes in your total? Probably under 3 amps if LED.

 On 9/8/2021 7:22 AM, A Lumley wrote:

> 

> <andrew.lumley(at)sympatico.ca>

>

> My calculations are definitely on the conservative side. I 

> distributed the loads such that I could fly on the Aux bus and Engine 

> busses alone in IMC if I were to lose the primary alternator or 

> otherwise had to shut down the main bus.

>

> My aux bus looks like this:

>

> Pitot Heat (7 Amps)

> GTN 750 Xi GPS/NAV/COM (3.45 Amps)

> G3X PFD 1 (2 Amps)

> 3x GSA28 Autopilot Servos (1.5 Amps)

> 3x Trim Servos (1.5 Amps)

> GMA245 Audio Panel (1 Amp)

> GTX 45R Transponder (1 Amp)

> GEA24 (0.43 Amps)

> #1 ADAHRS (0.2 Amps)

> G5 Backup (0.2 Amps)

> GMC 507 Autopilot (0.2 Amps)

> #1 GMU11 (0.1 Amps)

> Annunciator Panel (0.1 Amps)

> Total: 18.7 Amps

>

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_________________
Charlie

johnbright

Joined: 14 Dec 2011
Posts: 166
Location: Newport News, VA

Posted: Thu Sep 09, 2021 3:42 pm Post subject: Re: Z101 in an RV-10

Re A Lumley RV-10 Electrical Schematic V1.0 from seventh post prior to this one.



Voltage regulators...



Grounds are redundant, should go to separate points, ref install manual, failure of one is benign and not discoverable in flight or preflight. I put physical inspection on annual check list.



Voltage sense draws 22mA at 12.5V (LR3C-14, measured in off state), parasitic load on battery 1 AH in 45 hours. I put the one for the aux regulator on the engine bus, ref schematic in signature, folder 1).



I'm curious what voltage setpoints have been chosen for the main and aux regulators.

_________________
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

A Lumley

Joined: 12 May 2021
Posts: 10
Location: Ontario, Canada

Posted: Fri Sep 10, 2021 3:58 am Post subject: Re: Z101 in an RV-10

Kelly, good point about the alternating pumps. Of course normally both pumps will be operating for takeoff and landing. The bus will be sized for both pumps to be operating but if the main alternator fails I guess there’s no reason for more than one pump at a time. 



John, the 2 grounds will be independently grounded to the same ground bus. I can show that better in the schematic however. Also I didn’t realize that the sense pin had a parasitic draw when off, is that in the manual? I’ll revisit that. I plan on having the same voltage set points for both regulators. The aux will be normally off. If the main fails, I’ll get a low voltage indication and will take the main alternator offline manually before engaging the aux alternator.

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Sep 10, 2021 9:20 pm Post subject: Z101 in an RV-10

 	  Quote: 	
		  

 I'm curious what voltage setpoints have been chosen for the main and aux regulators. 	


   Why so expensive a regulator on the aux alternator?

   That regulator will see perhaps a hand-full of hours

   operation over the lifetime of the airplane under

   Plan-B conditions where the need for lv warning

   and ov protection is vanishingly small. That

   alternator/regulator gets preflight tested each

   flight-cycle. I.e. every tank full of fuel.



   Since plan-b operations are stand-alone and

   short duration, a full-up alternator controller

   adds no value . . . only expense and complexity.



 

   Bob . . .



   Un impeachable logic: George Carlin asked, "If black boxes

   survive crashes, why don't they make the whole airplane

   out of that stuff?"

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Sep 10, 2021 9:24 pm Post subject: Z101 in an RV-10

 	  Quote: 	
		  



 Voltage regulators...



 Grounds are redundant, should go to separate points, ref install manual, failure of

 one is benign and not discoverable in flight or preflight. I put physical inspection

 on annual check list. 	


   But not necessary on a metal airplane where the

   regulator is mounted on a high integrity airframe

   ground . . . dual wired grounds are indicated

   for non-metalic airframes where no 'natural',

   high quality ground is available.



 

   Bob . . .



   Un impeachable logic: George Carlin asked, "If black boxes

   survive crashes, why don't they make the whole airplane

   out of that stuff?"

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Sep 10, 2021 9:37 pm Post subject: Z101 in an RV-10

At 09:22 AM 9/8/2021, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "A Lumley" <andrew.lumley(at)sympatico.ca>



 My calculations are definitely on the conservative side. I distributed the loads such that I could fly on the Aux bus and Engine busses alone in IMC if I were to lose the primary alternator or otherwise had to shut down the main bus.



 My aux bus looks like this: 	


    Others have already suggested adjustments

    to this list. I would add this suggestion:



    Download the form at:



  http://www.aeroelectric.com/PPS/Load_Analysis/Blank_Form.pdf



    This is similar to the form I and others used in

    load analysis required for type certification of

    part 23 and 25 aircraft.



    Use a page per bus. Make a list of EACH feeder from

    the bus that includes function label, protection

    size and wire size. Then fill the blank with the

    ENERGY CONSUMPTION value for each feeder under

    each flight condition.



    Intermittent loads are not part of the energy

    consumption study. This includes transmit

    current of comm radios. Taxi lights, landing

    gear pump motors, trim actuators, etc.



    The sums at the bottom of the form are used

    to validate size selection of each power source

    for adequacy to meet energy management design

    goals.

 `



 

   Bob . . .



   Un impeachable logic: George Carlin asked, "If black boxes

   survive crashes, why don't they make the whole airplane

   out of that stuff?"

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