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Z101 in an RV-10
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A Lumley



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

PostPosted: Fri Sep 03, 2021 1:54 pm    Post subject: Z101 in an RV-10 Reply with quote

Good evening all,

I'm working away on an electrical architecture for my RV-10 based on Z-101B. I haven't started to install the system yet but I have a question about how I will actually install the electrical system.

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. 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...

The only solution I can imagine would be to leave the battery in the tail and move the battery contactor forward to the firewall. This would leave a long length of unprotected wire but I would have that anyways with the second contactor coming forward to the tie point...

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

Andrew


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PostPosted: Fri Sep 03, 2021 2:56 pm    Post subject: Z101 in an RV-10 Reply with quote

Andrew,
Why don't you mount the start solenoid on the firewall and run a #2 from the master solenoid in tail cone forward to start solenoid on firewall.
Then use the battery side of the start solenoid as the main terminus for the other loads. It sounds like you have several sub-systems to feed so you may want to use an additional stud terminal mounted near the start solenoid, with a jumper to the battery side of the start solenoid, to handle the quantity of wires.
Are you in Canada?
-Jeff

On Friday, September 3, 2021, 03:05:13 PM PDT, A Lumley <andrew.lumley(at)sympatico.ca> wrote:




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

Good evening all,

I'm working away on an electrical architecture for my RV-10 based on Z-101B. I haven't started to install the system yet but I have a question about how I will...

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. 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...

The only solution I can imagine would be to leave the battery in the tail and move the battery contactor forward to the firewall. This would leave a long length of unprotected wire but I would have that anyways with the second contactor coming forward to the tie point...

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

Andrew

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A Lumley



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

PostPosted: Fri Sep 03, 2021 4:52 pm    Post subject: Re: Z101 in an RV-10 Reply with quote

Hey Jeff, I am in Canada. That is my plan for the loads downstream of the battery contactor. But the Z-101 schematic also has several loads connected to the battery side of the battery contactor (hot battery bus and alternate feeds for the aux and engine busses). It's these loads that I'm trying to prevent running a second 2AWG cable for.

Andrew


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PostPosted: Sat Sep 04, 2021 12:07 pm    Post subject: Z101 in an RV-10 Reply with quote

Hi Andrew, where in Canada? I'm in Vancouver.

Have you done an Electrical Load Analysis on your hot battery loads? I'm finding it hard to believe that you would need anything close to 2 AWG for those combined loads. What continuous load are we talking about here?
On Fri, Sep 3, 2021 at 5:57 PM A Lumley <andrew.lumley(at)sympatico.ca (andrew.lumley(at)sympatico.ca)> wrote:

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

Hey Jeff, I am in Canada. That is my plan for the loads downstream of the battery contactor. But the Z-101 schematic also has several loads connected to the battery side of the battery contactor (hot battery bus and alternate feeds for the aux and engine busses). It's these loads that I'm trying to prevent running a second 2AWG cable for.

Andrew




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A Lumley



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

PostPosted: Sat Sep 04, 2021 1:06 pm    Post subject: Re: Z101 in an RV-10 Reply with quote

I'm in Belleville, 2 hours from Toronto.

The hot battery bus itself is only about 0.5 amps for a few overhead lights. The issue is that the Z-101 schematic has the ability to power the aux and engine busses through relays attached to the battery side of the battery contactor. My engine bus will draw 15-20 amps (SDS EFI) when both fuel pumps are running. The Aux bus includes the PFD, GPS, pitot heat, autopilot, and a few other small loads that will total another 15-20 amps with the pitot heat operating.

I'm thinking I'll need a separate cable of about 4 AWG running forward from the battery in addition to the 2 AWG starter cable. Just wondering if there is a better way, perhaps not.


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PostPosted: Sat Sep 04, 2021 1:48 pm    Post subject: Z101 in an RV-10 Reply with quote

I think you could get away with 8AWG rather than 4 AWG for the loads you describe but let's think about this another way.

In case of a forced landing, we want to be able to disconnect the 2 AWG cable from the battery so that when we hit a fence post we don't have a leaking fuel line and a big spark 5 feet from our asses. Putting the relay as close to the battery accomplishes this. If we then run a 4 AWG wire along the same route with no way to disconnect it from the battery, are we any better off? If you're going to accept a large live wire running along the fuselage, will it help that the 2 AWG is cold and the 4 AWG is hot? Might as well just leave the 2 AWG hot and move the relay to the front as you first described.
The only other solutions I can think of are
1. Relays on both wires and dual fed engine and aux busses. In a forced landing you shut off both relays.
2. A second battery in the engine compartment.
3. A second alternator and feed your dual fed engine and aux busses from each alternator, dropping the battery feed.
On Sat, Sep 4, 2021 at 2:10 PM A Lumley <andrew.lumley(at)sympatico.ca (andrew.lumley(at)sympatico.ca)> wrote:

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

I'm in Belleville, 2 hours from Toronto.

The hot battery bus itself is only about 0.5 amps for a few overhead lights. The issue is that the Z-101 schematic has the ability to power the aux and engine busses through relays attached to the battery side of the battery contactor. My engine bus will draw 15-20 amps (SDS EFI) when both fuel pumps are running. The Aux bus includes the PFD, GPS, pitot heat, autopilot, and a few other small loads that will total another 15-20 amps with the pitot heat operating.

I'm thinking I'll need a separate cable of about 4 AWG running forward from the battery in addition to the 2 AWG starter cable. Just wondering if there is a better way, perhaps not.




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Kellym



Joined: 10 Jan 2006
Posts: 1700
Location: Sun Lakes AZ

PostPosted: Sat Sep 04, 2021 2:49 pm    Post subject: Z101 in an RV-10 Reply with quote

I think the real analysis is that you need two separate power sources
for the fuel injection and the ignition. Using a single battery does not
accomplish that, no matter how you wire it. I believe you would have to
have two batteries, and probably should have two alternators.
However, that gets back to why do you want an aircraft for IFR that
requires the complexity of two separate electrical systems and the
electrical components to allow them to operate separately?
Simplicity is your friend, especially when IFR.
Regardless of advertising claims, a port fuel injection system with 6
individual electrically operated solenoids does not significantly
improve power or fuel economy over the mechanical fuel injection system
the IO-540 is designed with or the Air Flow performance experimental
fuel injection. They also eliminate the need for electrical fuel pumps
to operate continuously, as the stock mechanical pump is adequate for
almost all in-flight situations.
Having both ignitions systems electrically dependent again introduces
complexity. You really want your engine to be able to run indefinitely
without external power if all electrics fail.
You can still have the benefits of electronic ignition without the need
for external power if you install 2 PMag systems, and they only need
external power for starting.
Even if the full SDS system gets you an extra 10 kts (unlikely) it
only reduces the time to fly a 500nm flight by perhaps 10-15 minutes.

If you eliminate the need for external power for the engine to run, you
can have adequate backup power for avionics without having to install
dual electrical systems. Most EFIS have backup battery systems that
allow shutting of the master and will continue to operate for 45 min or
more. You can equip a Nav/com with similar backup battery.

Just my opinion with 40+ yrs of IFR flying and 5 years of flying my IFR
RV-10.
Kelly

On 9/4/2021 2:47 PM, Sebastien wrote:
Quote:
I think you could get away with 8AWG rather than 4 AWG for the loads you
describe but let's think about this another way.

In case of a forced landing, we want to be able to disconnect the 2 AWG
cable from the battery so that when we hit a fence post we don't have a
leaking fuel line and a big spark 5 feet from our asses. Putting the
relay as close to the battery accomplishes this. If we then run a 4 AWG
wire along the same route with no way to disconnect it from the battery,
are we any better off? If you're going to accept a large live wire
running along the fuselage, will it help that the 2 AWG is cold and the
4 AWG is hot? Might as well just leave the 2 AWG hot and move the relay
to the front as you first described.

The only other solutions I can think of are

1. Relays on both wires and dual fed engine and aux busses. In a forced
landing you shut off both relays.
2. A second battery in the engine compartment.
3. A second alternator and feed your dual fed engine and aux busses from
each alternator, dropping the battery feed.

On Sat, Sep 4, 2021 at 2:10 PM A Lumley <andrew.lumley(at)sympatico.ca
<mailto:andrew.lumley(at)sympatico.ca>> wrote:


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

I'm in Belleville, 2 hours from Toronto.

The hot battery bus itself is only about 0.5 amps for a few overhead
lights. The issue is that the Z-101 schematic has the ability to
power the aux and engine busses through relays attached to the
battery side of the battery contactor. My engine bus will draw 15-20
amps (SDS EFI) when both fuel pumps are running. The Aux bus
includes the PFD, GPS, pitot heat, autopilot, and a few other small
loads that will total another 15-20 amps with the pitot heat operating.

I'm thinking I'll need a separate cable of about 4 AWG running
forward from the battery in addition to the 2 AWG starter cable.
Just wondering if there is a better way, perhaps not.




Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=503043#503043
<http://forums.matronics.com/viewtopic.php?p=503043#503043>






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A Lumley



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

PostPosted: Sat Sep 04, 2021 4:07 pm    Post subject: Re: Z101 in an RV-10 Reply with quote

Thanks for the comments Kelly. For starters while I am planning for a single battery, I am definitely installing dual alternators. I believe a second battery would be of marginal benefit given the chance of dual alternator failure and subsequent battery failure.

I do appreciate the comments on the electronic fuel injection though. I'm quite set on electronic ignition but I'm not 100% set on electronic injection to go with it. I'll have to do some more research. It would certainly give me less electrical concerns to install a mechanical injection system.


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Kellym



Joined: 10 Jan 2006
Posts: 1700
Location: Sun Lakes AZ

PostPosted: Sat Sep 04, 2021 5:32 pm    Post subject: Z101 in an RV-10 Reply with quote

I agree with the electronic ignition. There are definite advantages.
However, there are trade-offs. AFAIK, only P Mag offers electronic
ignition that isn't dependent on ship's power.
Electrical systems come down to what can fail that takes the system
down. It takes effort to design a system that can't be brought down by
say failure of the master relay, master switch, etc. There is a recent
article of an RV-10 that was grounded by ignition switch failure,
fortunately on the ground.
Kelly

On 9/4/2021 5:07 PM, A Lumley wrote:
Quote:


Thanks for the comments Kelly. For starters while I am planning for a single battery, I am definitely installing dual alternators. I believe a second battery would be of marginal benefit given the chance of dual alternator failure and subsequent battery failure.

I do appreciate the comments on the electronic fuel injection though. I'm quite set on electronic ignition but I'm not 100% set on electronic injection to go with it. I'll have to do some more research. It would certainly give me less electrical concerns to install a mechanical injection system.




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Voyager



Joined: 30 Jun 2020
Posts: 77

PostPosted: Sat Sep 04, 2021 5:42 pm    Post subject: Z101 in an RV-10 Reply with quote

I am currently finalizing my schematics for my S-21 and I am building a system based mostly on the Z-14 system. I am planning on dual 40 amp alternators and two independent buses, but with crossfeed so that both batteries can be used for engine start and in the case that one alternator or battery fails I can run everything on the remaining battery or alternator.

I plan to run two fat wires from the baggage floor mounted batteries to the firewall. I will probably use 2 AWG, but RANS lists 4 AWG in their schematic (for a single battery installation) so that may be adequate since the batteries share current during starting. Since I will have two battery buses in addition to the two main buses, I will probably run 14 AWG for each of those as that will handle 15 amps each and 30 amps is more than enough for the always hot accessories.

I am also leaning towards SDS for both ignition and EFI. I have owned and driven a variety of cars and trucks and off-road and OTR equipment since the early 70s and I will tell you that magnetos, carbs, mechanical FI and mechanical fuel pumps are no more reliable than modern EFI and electronic ignition systems and I would argue much less reliable. I have not had nearly the trouble with any of my cars in the last 20 years that have had EFI and EI as I had with cars equipped with carbs and points ignition or my 182 with carb and mags. An SDS system with dual ECUs, and dual electric fuel pumps operated by two alternators and two batteries is probably 10X more reliable than a magneto equipped airplane with mechanical FI and mechanical fuel pump. I’d love to see some real statistics from the aviation world, but using the auto world as a benchmark gives me good confidence that my 10X estimate isn’t far off.

Sent from my iPad

Quote:
On Sep 4, 2021, at 8:11 PM, A Lumley <andrew.lumley(at)sympatico.ca> wrote:



Thanks for the comments Kelly. For starters while I am planning for a single battery, I am definitely installing dual alternators. I believe a second battery would be of marginal benefit given the chance of dual alternator failure and subsequent battery failure.

I do appreciate the comments on the electronic fuel injection though. I'm quite set on electronic ignition but I'm not 100% set on electronic injection to go with it. I'll have to do some more research. It would certainly give me less electrical concerns to install a mechanical injection system.




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http://forums.matronics.com/viewtopic.php?p=503046#503046











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PostPosted: Sat Sep 04, 2021 6:49 pm    Post subject: Z101 in an RV-10 Reply with quote

Kelly it's not a single battery, it's a single battery and an alternator. If the alternator quits the battery gets you on the ground. Failures of properly maintained batteries are very rare, but if the battery fails in flight you won't notice because the alternator keeps going. A second alternator can greatly extend the time in the air, but most second alternators are 20A at most so for Andrew's requirements not enough for indefinite flight.

Where are you getting your data that EFI does not reduce fuel consumption? I haven't seen any real world data but the advertising shows significant reductions (though at $2.00 / liter, not enough to offset the purchase price)

On Sat, Sep 4, 2021 at 7:17 PM Kelly McMullen <kellym(at)aviating.com (kellym(at)aviating.com)> wrote:

Quote:
--> AeroElectric-List message posted by: Kelly McMullen <kellym(at)aviating.com (kellym(at)aviating.com)>

I think the real analysis is that you need two separate power sources
for the fuel injection and the ignition. Using a single battery does not
accomplish that, no matter how you wire it. I believe you would have to
have two batteries, and probably should have two alternators.
However, that gets back to why do you want an aircraft for IFR that
requires the complexity of two separate electrical systems and the
electrical components to allow them to operate separately?
Simplicity is your friend, especially when IFR.
Regardless of advertising claims, a port fuel injection system with 6
individual electrically operated solenoids does not significantly
improve power or fuel economy over the mechanical fuel injection system
the IO-540 is designed with or the Air Flow performance experimental
fuel injection. They also eliminate the need for electrical fuel pumps
to operate continuously, as the stock mechanical pump is adequate for
almost all in-flight situations.
Having both ignitions systems electrically dependent again introduces
complexity. You really want your engine to be able to run indefinitely
without external power if all electrics fail.
You can still have the benefits of electronic ignition without the need
for external power if you install 2 PMag systems, and they only need
external power for starting.
  Even if the full SDS system gets you an extra 10 kts (unlikely) it
only reduces the time to fly a 500nm flight by perhaps 10-15 minutes.

If you eliminate the need for external power for the engine to run, you
can have adequate backup power for avionics without having to install
dual electrical systems. Most EFIS have backup battery systems that
allow shutting of the master and will continue to operate for 45 min or
more. You can equip a Nav/com with similar backup battery.

Just my opinion with 40+ yrs of IFR flying and 5 years of flying my IFR
RV-10.
Kelly

On 9/4/2021 2:47 PM, Sebastien wrote:
> I think you could get away with 8AWG rather than 4 AWG for the loads you
> describe but let's think about this another way.
>
> In case of a forced landing, we want to be able to disconnect the 2 AWG
> cable from the battery so that when we hit a fence post we don't have a
> leaking fuel line and a big spark 5 feet from our asses. Putting the
> relay as close to the battery accomplishes this. If we then run a 4 AWG
> wire along the same route with no way to disconnect it from the battery,
> are we any better off? If you're going to accept a large live wire
> running along the fuselage, will it help that the 2 AWG is cold and the
> 4 AWG is hot? Might as well just leave the 2 AWG hot and move the relay
> to the front as you first described.
>
> The only other solutions I can think of are
>
> 1. Relays on both wires and dual fed engine and aux busses. In a forced
> landing you shut off both relays.
> 2. A second battery in the engine compartment.
> 3. A second alternator and feed your dual fed engine and aux busses from
> each alternator, dropping the battery feed.
>
> On Sat, Sep 4, 2021 at 2:10 PM A Lumley <andrew.lumley(at)sympatico.ca (andrew.lumley(at)sympatico.ca)
> <mailto:andrew.lumley(at)sympatico.ca (andrew.lumley(at)sympatico.ca)>> wrote:
>
>     --> AeroElectric-List message posted by: "A Lumley"
>     <andrew.lumley(at)sympatico.ca (andrew.lumley(at)sympatico.ca) <mailto:andrew.lumley(at)sympatico.ca (andrew.lumley(at)sympatico.ca)>>
>
>     I'm in Belleville, 2 hours from Toronto.
>
>     The hot battery bus itself is only about 0.5 amps for a few overhead
>     lights. The issue is that the Z-101 schematic has the ability to
>     power the aux and engine busses through relays attached to the
>     battery side of the battery contactor. My engine bus will draw 15-20
>     amps (SDS EFI) when both fuel pumps are running. The Aux bus
>     includes the PFD, GPS, pitot heat, autopilot, and a few other small
>     loads that will total another 15-20 amps with the pitot heat operating.
>
>     I'm thinking I'll need a separate cable of about 4 AWG running
>     forward from the battery in addition to the 2 AWG starter cable.
>     Just wondering if there is a better way, perhaps not.
>
>
>
>
>     Read this topic online here:
>
>     http://forums.matronics.com/viewtopic.php?p=503043#503043
>     <http://forums.matronics.com/viewtopic.php?p=503043#503043>
>
>
>
>
>
>
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Voyager



Joined: 30 Jun 2020
Posts: 77

PostPosted: Sat Sep 04, 2021 7:46 pm    Post subject: Re: Z101 in an RV-10 Reply with quote

I will argue that the folks at GAMI have provided this data for many years now. What they do in tuning injectors in mechanical systems is essentially what the ECU can do in real-time in an EFI system. Now, I don’t know if the SDS ECU is that a sophisticated, but auto EFI systems can adjust the PWM of each individual injector to optimized each cylinder. This absolutely improves both fuel economy and emissions performance.

So, if you believe GAMI’s data in regard to balancing mechanical injectors then you should believe that EFI will bring similar performance improvements if properly implemented.


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Kellym



Joined: 10 Jan 2006
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Location: Sun Lakes AZ

PostPosted: Sat Sep 04, 2021 7:47 pm    Post subject: Z101 in an RV-10 Reply with quote

I did not say that EFI did not reduce fuel consumption or increase
power. What I said was electronically controlled port fuel injection is
not going to reduce fuel consumption or increase power enough to give up
the reliability of mechanical fuel injection. Electronic fuel injection
is very reliable in cars, where an electrical failure just causes the
engine to die. In an aircraft the electronic controller and injectors
are a single point of failure. Electronic fuel injection has almost zero
operating experience in aircraft, compared to 60 years of mechanical
fuel injection. When Lycoming or Continental adopt electronic fuel
injection, I might think about it. Aircraft applications are very
different from automotive engines operating characteristics.
A single battery is a single battery no matter how many alternators you
have. No different than a single master relay.

On 9/4/2021 7:48 PM, Sebastien wrote:
Quote:
Kelly it's not a single battery, it's a single battery and an
alternator. If the alternator quits the battery gets you on the ground.
Failures of properly maintained batteries are very rare, but if the
battery fails in flight you won't notice because the alternator keeps
going. A second alternator can greatly extend the time in the air, but
most second alternators are 20A at most so for Andrew's requirements not
enough for indefinite flight.

Where are you getting your data that EFI does not reduce fuel
consumption? I haven't seen any real world data but the advertising
shows significant reductions (though at $2.00 / liter, not enough to
offset the purchase price)

On Sat, Sep 4, 2021 at 7:17 PM Kelly McMullen <kellym(at)aviating.com
<mailto:kellym(at)aviating.com>> wrote:


<kellym(at)aviating.com <mailto:kellym(at)aviating.com>>

I think the real analysis is that you need two separate power sources
for the fuel injection and the ignition. Using a single battery does
not
accomplish that, no matter how you wire it. I believe you would have to
have two batteries, and probably should have two alternators.
However, that gets back to why do you want an aircraft for IFR that
requires the complexity of two separate electrical systems and the
electrical components to allow them to operate separately?
Simplicity is your friend, especially when IFR.
Regardless of advertising claims, a port fuel injection system with 6
individual electrically operated solenoids does not significantly
improve power or fuel economy over the mechanical fuel injection system
the IO-540 is designed with or the Air Flow performance experimental
fuel injection. They also eliminate the need for electrical fuel pumps
to operate continuously, as the stock mechanical pump is adequate for
almost all in-flight situations.
Having both ignitions systems electrically dependent again introduces
complexity. You really want your engine to be able to run indefinitely
without external power if all electrics fail.
You can still have the benefits of electronic ignition without the need
for external power if you install 2 PMag systems, and they only need
external power for starting.
  Even if the full SDS system gets you an extra 10 kts (unlikely) it
only reduces the time to fly a 500nm flight by perhaps 10-15 minutes.

If you eliminate the need for external power for the engine to run, you
can have adequate backup power for avionics without having to install
dual electrical systems. Most EFIS have backup battery systems that
allow shutting of the master and will continue to operate for 45 min or
more. You can equip a Nav/com with similar backup battery.

Just my opinion with 40+ yrs of IFR flying and 5 years of flying my IFR
RV-10.
Kelly

On 9/4/2021 2:47 PM, Sebastien wrote:
> I think you could get away with 8AWG rather than 4 AWG for the
loads you
> describe but let's think about this another way.
>
> In case of a forced landing, we want to be able to disconnect the
2 AWG
> cable from the battery so that when we hit a fence post we don't
have a
> leaking fuel line and a big spark 5 feet from our asses. Putting the
> relay as close to the battery accomplishes this. If we then run a
4 AWG
> wire along the same route with no way to disconnect it from the
battery,
> are we any better off? If you're going to accept a large live wire
> running along the fuselage, will it help that the 2 AWG is cold
and the
> 4 AWG is hot? Might as well just leave the 2 AWG hot and move the
relay
> to the front as you first described.
>
> The only other solutions I can think of are
>
> 1. Relays on both wires and dual fed engine and aux busses. In a
forced
> landing you shut off both relays.
> 2. A second battery in the engine compartment.
> 3. A second alternator and feed your dual fed engine and aux
busses from
> each alternator, dropping the battery feed.
>
> On Sat, Sep 4, 2021 at 2:10 PM A Lumley
<andrew.lumley(at)sympatico.ca <mailto:andrew.lumley(at)sympatico.ca>
> <mailto:andrew.lumley(at)sympatico.ca
<mailto:andrew.lumley(at)sympatico.ca>>> wrote:
>
>     
>     <andrew.lumley(at)sympatico.ca
<mailto:andrew.lumley(at)sympatico.ca>
<mailto:andrew.lumley(at)sympatico.ca <mailto:andrew.lumley(at)sympatico.ca>>>
>
>     I'm in Belleville, 2 hours from Toronto.
>
>     The hot battery bus itself is only about 0.5 amps for a few
overhead
>     lights. The issue is that the Z-101 schematic has the ability to
>     power the aux and engine busses through relays attached to the
>     battery side of the battery contactor. My engine bus will
draw 15-20
>     amps (SDS EFI) when both fuel pumps are running. The Aux bus
>     includes the PFD, GPS, pitot heat, autopilot, and a few other
small
>     loads that will total another 15-20 amps with the pitot heat
operating.
>
>     I'm thinking I'll need a separate cable of about 4 AWG running
>     forward from the battery in addition to the 2 AWG starter cable.
>     Just wondering if there is a better way, perhaps not.
>
>
>
>
>     Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=503043#503043
<http://forums.matronics.com/viewtopic.php?p=503043#503043>
>     <http://forums.matronics.com/viewtopic.php?p=503043#503043
<http://forums.matronics.com/viewtopic.php?p=503043#503043>>
>
>
>
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Foghorn



Joined: 22 Jun 2020
Posts: 3
Location: Virginia Beach

PostPosted: Sun Sep 05, 2021 4:01 am    Post subject: Z101 in an RV-10 Reply with quote

Here is my dual alternator/single battery SDS schematic for my IFR RV8. The battery will be an EarthX 900 on the firewall.
The primary ALT is set at 14.4, the AUX ALT is set at 13.9 and the ETX-900 is the final power source. Both ALTs and the AUX ENG BUS PWR will be on for all flight conditions. The AUX E-BUS will be open until needed.

This has now flown yet.


Jeff Parker
757-817-4929


Quote:
On 4Sep, 2021, at 17:06, A Lumley <andrew.lumley(at)sympatico.ca (andrew.lumley(at)sympatico.ca)> wrote:
--> AeroElectric-List message posted by: "A Lumley" <andrew.lumley(at)sympatico.ca (andrew.lumley(at)sympatico.ca)>I'm in Belleville, 2 hours from Toronto.The hot battery bus itself is only about 0.5 amps for a few overhead lights. The issue is that the Z-101 schematic has the ability to power the aux and engine busses through relays attached to the battery side of the battery contactor. My engine bus will draw 15-20 amps (SDS EFI) when both fuel pumps are running. The Aux bus includes the PFD, GPS, pitot heat, autopilot, and a few other small loads that will total another 15-20 amps with the pitot heat operating.I'm thinking I'll need a separate cable of about 4 AWG running forward from the battery in addition to the 2 AWG starter cable. Just wondering if there is a better way, perhaps not.Read this topic online here:http://forums.matronics.com/viewtopic.php?p=503043#503043



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Voyager



Joined: 30 Jun 2020
Posts: 77

PostPosted: Sun Sep 05, 2021 4:43 am    Post subject: Re: Z101 in an RV-10 Reply with quote

Kellym wrote:
I did not say that EFI did not reduce fuel consumption or increase
power. What I said was electronically controlled port fuel injection is
not going to reduce fuel consumption or increase power enough to give up
the reliability of mechanical fuel injection. Electronic fuel injection
is very reliable in cars, where an electrical failure just causes the
engine to die. In an aircraft the electronic controller and injectors
are a single point of failure. Electronic fuel injection has almost zero
operating experience in aircraft, compared to 60 years of mechanical
fuel injection. When Lycoming or Continental adopt electronic fuel
injection, I might think about it. Aircraft applications are very
different from automotive engines operating characteristics.
A single battery is a single battery no matter how many alternators you
have. No different than a single master relay.


You are making the assumption that mechanical FI is more reliable than electronic FI and I don’t agree that this is a valid assumption. I am not sure there is good data available to make such a decision, but I think it is incorrect to automatically assume that mechanical is more reliable than electrical. I’d love to see real data on MFI vs EFI as my experience in the auto world is that EFI is one of the most reliable parts on an engine. Then again, most cars did skip MFI and went straight from carbs to EFI as MFI would not have helped them pass the emissions regulations.

Yes, a single battery is a single point of failure, but what difference does that make other than when starting and, most of the time at least, that is done on the ground. The EFI doesn’t care where the electrons come from. So, with both alternators and battery, you have a redundant system and the odds of both failing on the same flight are low. And batteries rarely fail suddenly. I have had only one battery fail suddenly in 50+ years of owning vehicles. That was on a new Chevy Equinox that just wouldn’t crank one morning. It was only 4 months old and the battery apparently had a connection open internally, obviously due to a factory defect. Every other battery has given plenty of warning (slow cranking generally) that it was on its last legs. As long as you don’t ignore the warning, it is almost always possible to replace the battery before complete failure.


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Ceengland



Joined: 11 Oct 2020
Posts: 378
Location: MS

PostPosted: Sun Sep 05, 2021 5:26 am    Post subject: Z101 in an RV-10 Reply with quote

On Sun, Sep 5, 2021 at 7:47 AM Voyager <m.whiting(at)frontier.com> wrote:

[quote]
>
Kellym wrote:
> I did not say that EFI did not reduce fuel consumption or increase
> power. What I said was electronically controlled port fuel injection is
> not going to reduce fuel consumption or increase power enough to give up
> the reliability of mechanical fuel injection. Electronic fuel injection
> is very reliable in cars, where an electrical failure just causes the
> engine to die. In an aircraft the electronic controller and injectors
> are a single point of failure. Electronic fuel injection has almost zero
> operating experience in aircraft, compared to 60 years of mechanical
> fuel injection. When Lycoming or Continental adopt electronic fuel
> injection, I might think about it. Aircraft applications are very
> different from automotive engines operating characteristics.
> A single battery is a single battery no matter how many alternators you
> have. No different than a single master relay.
>
You are making the assumption that mechanical FI is more reliable than
electronic FI and I don’t agree that this is a valid assumption. I am not
sure there is good data available to make such a decision, but I think it
is incorrect to automatically assume that mechanical is more reliable than
electrical. I’d love to see real data on MFI vs EFI as my experience in
the auto world is that EFI is one of the most reliable parts on an engine


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Kellym



Joined: 10 Jan 2006
Posts: 1700
Location: Sun Lakes AZ

PostPosted: Sun Sep 05, 2021 6:39 am    Post subject: Z101 in an RV-10 Reply with quote

There is no question that mechanical fuel injection has been extremely
reliable on aircraft engines. They have been employed since the early
1960s. The Bendix variety generally goes to TBO with the engine. The
Continental needs periodic pressure adjustments that affect mixture but
not reliability. You just won't find aircraft accidents from mechanical
fuel injection failures....just lack of fuel or fuel selector
mismanagement. I've flown behind mechanical injection engines for 23
years, behind carburetors for 24 years.
Automotive mechanical injection systems started in the late 50s, were
widely used on more expensive autos from the late 70s (think Bosch),
were very easy to adjust for mixture and generally needed nothing else.
The early electronic injection systems used by VW and Porsche were
terrible and resulted in many engine fires.
The current automotive systems are not just electronic, but are also
direct injection, which you won't see in aircraft systems. Most of their
advantages come from the direct cylinder injection, which came from
diesel applications. Even those have fairly common failures...my 8 month
old vehicle had to go to the dealer just last month with multiple
electronic failures that were traced to a failure in the wiring
harness...in a mass manufactured vehicle, not a hand wired aircraft.
Fortunately it was designed with a limp home mode. Low power, limp home
is ok for autos, not for aircraft.
While SDS may have dual controllers, they still only have one injector
per cylinder. Yes electronic injectors fail. I had to have a set of
diesel injectors replaced less than 10 years ago because of frequent
failures, under a manufacturer service bulletin (not just my auto).
I've seen a dual electronic ignition fail on an aircraft, on takeoff,
because of an intermittent failure of an automotive voltage regulator,
fried the electronic ignitions, yes, both of them.
Automotive reliability simply does not translate directly to aviation.
There are really only two automotive engines that have endured in
aviation, and neither one normally has electronic anything.
Just my experience from 50 years of working on autos and 45 years
working on aircraft.
Kelly
A&P/IA

On 9/5/2021 6:19 AM, Charlie England wrote:
Quote:


On Sun, Sep 5, 2021 at 7:47 AM Voyager <m.whiting(at)frontier.com
<mailto:m.whiting(at)frontier.com>> wrote:


<m.whiting(at)frontier.com <mailto:m.whiting(at)frontier.com>>


Kellym wrote:
> I did not say that EFI did not reduce fuel consumption or increase
> power. What I said was electronically controlled port fuel
injection is
> not going to reduce fuel consumption or increase power enough to
give up
> the reliability of mechanical fuel injection. Electronic fuel
injection
> is very reliable in cars, where an electrical failure just causes
the
> engine to die. In an aircraft the electronic controller and
injectors
> are a single point of failure. Electronic fuel injection has
almost zero
> operating experience in aircraft, compared to 60 years of mechanical
> fuel injection. When Lycoming or Continental adopt electronic fuel
> injection, I might think about it. Aircraft applications are very
> different from automotive engines operating characteristics.
> A single battery is a single battery no matter how many
alternators you
> have. No different than a single master relay.
>


You are making the assumption that mechanical FI is more reliable
than electronic FI and I don’t agree that this is a valid
assumption.  I am not sure there is good data available to make such
a decision, but I think it is incorrect to automatically assume that
mechanical is more reliable than electrical.  I’d love to see real
data on MFI vs EFI as my experience in the auto world is that EFI is
one of the most reliable parts on an engine.  Then again, most cars
did skip MFI and went straight from carbs to EFI as MFI would not
have helped them pass the emissions regulations.

Yes, a single battery is a single point of failure, but what
difference does that make other than when starting and, most of the
time at least, that is done on the ground.  The EFI doesn’t care
where the electrons come from.  So, with both alternators and
battery, you have a redundant system and the odds of both failing on
the same flight are low.  And batteries rarely fail suddenly.  I
have had only one battery fail suddenly in 50+ years of owning
vehicles.  That was on a new Chevy Equinox that just wouldn’t crank
one morning.  It was only 4 months old and the battery apparently
had a connection open internally, obviously due to a factory
defect.  Every other battery has given plenty of warning (slow
cranking generally) that it was on its last legs.  As long as you
don’t ignore the warning, it is almost always possible to replace
the battery before complete failure.


I've owned a MFI car, and I pray that I never have to own another. If
simple is the goal, a carb is the thing (single point of failure,
BTW...). But simple doesn't necessarily mean more reliable.

A battery *should not* be a 'single point of failure' in the sense of
terminating a flight, as long as the system architecture is properly
executed. Look at any of the Z figures; the alt B-lead is connected to
the bus on the load side of the master contactor. If the battery simply
dies, everything still works until engine shutdown. If the battery
develops a dead short internally, then your problem is either a lot
(explosively) bigger than electron supply, or you turn off the master,
and everything continues to work until engine shutdown. That business
about field wound alternators being 'unstable' without a battery
attached is just old hangar tales. A bit more 'ripple' in the DC is just
about the only thing that changes.

I don't know about every aftermarket EFI, but the SDS system does allow
tuning individual injector pulses, and they also make a fully redundant
system (two complete, independent controllers). Not available with any
'traditional' a/c system that I've ever seen. The aftermarket automotive
controllers also allow individual injector tuning, and it's possible to
configure a redundant system with those, as well.

Charlie

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Ceengland



Joined: 11 Oct 2020
Posts: 378
Location: MS

PostPosted: Sun Sep 05, 2021 8:23 am    Post subject: Z101 in an RV-10 Reply with quote

Well, yeah; it takes effort. That's why most of us are here on this list. Wink
I'm really grateful for a place where we can 'spitball' all kinds of ideas, and still have a few highly experienced 'shepherds' to keep us from straying too far into danger.
Charlie
On Sun, Sep 5, 2021 at 10:38 AM Kelly McMullen <kellym(at)aviating.com (kellym(at)aviating.com)> wrote:

Quote:
--> AeroElectric-List message posted by: Kelly McMullen <kellym(at)aviating.com (kellym(at)aviating.com)>

I agree with the electronic ignition. There are definite advantages.
However, there are trade-offs. AFAIK, only P Mag offers electronic
ignition that isn't dependent on ship's power.
Electrical systems come down to what can fail that takes the system
down. It takes effort to design a system that can't be brought down by
say failure of the master relay, master switch, etc. There is a recent
article of an RV-10 that was grounded by ignition switch failure,
fortunately on the ground.
Kelly

On 9/4/2021 5:07 PM, A Lumley wrote:
> --> AeroElectric-List message posted by: "A Lumley" <andrew.lumley(at)sympatico.ca (andrew.lumley(at)sympatico.ca)>
>
> Thanks for the comments Kelly. For starters while I am planning for a single battery, I am definitely installing dual alternators. I believe a second battery would be of marginal benefit given the chance of dual alternator failure and subsequent battery failure.
>
> I do appreciate the comments on the electronic fuel injection though. I'm quite set on electronic ignition but I'm not 100% set on electronic injection to go with it. I'll have to do some more research. It would certainly give me less electrical concerns to install a mechanical injection system.
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=503046#503046
>
>
>
>
>
>
>
>
>
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PostPosted: Sun Sep 05, 2021 9:08 am    Post subject: Re: Z101 in an RV-10 Reply with quote

Kellym wrote:
There is no question that mechanical fuel injection has been extremely
reliable on aircraft engines. They have been employed since the early
1960s. The Bendix variety generally goes to TBO with the engine. The
Continental needs periodic pressure adjustments that affect mixture but
not reliability. You just won't find aircraft accidents from mechanical
fuel injection failures....just lack of fuel or fuel selector
mismanagement. I've flown behind mechanical injection engines for 23
years, behind carburetors for 24 years.
Automotive mechanical injection systems started in the late 50s, were
widely used on more expensive autos from the late 70s (think Bosch),
were very easy to adjust for mixture and generally needed nothing else.
The early electronic injection systems used by VW and Porsche were
terrible and resulted in many engine fires.
The current automotive systems are not just electronic, but are also
direct injection, which you won't see in aircraft systems. Most of their
advantages come from the direct cylinder injection, which came from
diesel applications. Even those have fairly common failures...my 8 month
old vehicle had to go to the dealer just last month with multiple
electronic failures that were traced to a failure in the wiring
harness...in a mass manufactured vehicle, not a hand wired aircraft.
Fortunately it was designed with a limp home mode. Low power, limp home
is ok for autos, not for aircraft.
While SDS may have dual controllers, they still only have one injector
per cylinder. Yes electronic injectors fail. I had to have a set of
diesel injectors replaced less than 10 years ago because of frequent
failures, under a manufacturer service bulletin (not just my auto).
I've seen a dual electronic ignition fail on an aircraft, on takeoff,
because of an intermittent failure of an automotive voltage regulator,
fried the electronic ignitions, yes, both of them.
Automotive reliability simply does not translate directly to aviation.
There are really only two automotive engines that have endured in
aviation, and neither one normally has electronic anything.
Just my experience from 50 years of working on autos and 45 years
working on aircraft.


I agree that aircraft MFI is very reliable. I simply disagree with your assertion that EFI is somehow not reliable.

Early implementations of almost every new technology are less reliable than after they have a decade or so of service. Auto style port injection EFI is hardly a new technology now with at least three decades of refinement. GDI has some early teething troubles, but even that is pretty well proven now.

Fabric and tube is a reliable technology, but that doesn’t mean aluminum is not reliable even though many early aluminum airplanes had issues prior to fatigue being well understood. And as good as aluminum is now, it doesn’t mean that composites are not good. They had issues early on as the temperature dependence and resin to fabric proportions were sorted out. Everything new goes through a period of learning and refining.

I am not saying the wholesale adopt auto technology, as the environments are certainly different, however, many systems such as alternators, fuel systems and such really are not significantly different. High continuous power makes many auto engine installations challenging, but mostly from a cooling perspective. Cooled properly, most auto engines will run as long as most airplane engines. And high continuous power output really doesn’t matter for things like alternators and EFI. An alternator only knows RPM and load placed on it and neither is a function of the engine’s power out. Same for EFI. The injectors don’t really much care how wide the PWM signal is and that is the main thing that changes with higher power output. I actually suspect an airplane engine is a much nicer environment for an electronic fuel injector than is a car engine. Cars often run at much higher RPMs that airplanes so the injectors have to fire much faster and more often and cars often sit idling in traffic with very high under hood temperatures that airplanes only see occasionally.

I will leave you to your carbs and magnetos and happily use my electronic ignition and fuel injection. I do still have one carbureted motorcycle that often reminds me of just how much better EFI is on all of my other vehicles. Smile


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kenryan



Joined: 20 Oct 2009
Posts: 424

PostPosted: Sun Sep 05, 2021 9:57 am    Post subject: Z101 in an RV-10 Reply with 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."
On Sun, Sep 5, 2021 at 9:27 AM Kelly McMullen <kellym(at)aviating.com (kellym(at)aviating.com)> wrote:

Quote:
--> AeroElectric-List message posted by: Kelly McMullen <kellym(at)aviating.com (kellym(at)aviating.com)>

I think the real analysis is that you need two separate power sources
for the fuel injection and the ignition. Using a single battery does not
accomplish that, no matter how you wire it. I believe you would have to
have two batteries, and probably should have two alternators.
However, that gets back to why do you want an aircraft for IFR that
requires the complexity of two separate electrical systems and the
electrical components to allow them to operate separately?
Simplicity is your friend, especially when IFR.
Regardless of advertising claims, a port fuel injection system with 6
individual electrically operated solenoids does not significantly
improve power or fuel economy over the mechanical fuel injection system
the IO-540 is designed with or the Air Flow performance experimental
fuel injection. They also eliminate the need for electrical fuel pumps
to operate continuously, as the stock mechanical pump is adequate for
almost all in-flight situations.
Having both ignitions systems electrically dependent again introduces
complexity. You really want your engine to be able to run indefinitely
without external power if all electrics fail.
You can still have the benefits of electronic ignition without the need
for external power if you install 2 PMag systems, and they only need
external power for starting.
  Even if the full SDS system gets you an extra 10 kts (unlikely) it
only reduces the time to fly a 500nm flight by perhaps 10-15 minutes.

If you eliminate the need for external power for the engine to run, you
can have adequate backup power for avionics without having to install
dual electrical systems. Most EFIS have backup battery systems that
allow shutting of the master and will continue to operate for 45 min or
more. You can equip a Nav/com with similar backup battery.

Just my opinion with 40+ yrs of IFR flying and 5 years of flying my IFR
RV-10.
Kelly

On 9/4/2021 2:47 PM, Sebastien wrote:
> I think you could get away with 8AWG rather than 4 AWG for the loads you
> describe but let's think about this another way.
>
> In case of a forced landing, we want to be able to disconnect the 2 AWG
> cable from the battery so that when we hit a fence post we don't have a
> leaking fuel line and a big spark 5 feet from our asses. Putting the
> relay as close to the battery accomplishes this. If we then run a 4 AWG
> wire along the same route with no way to disconnect it from the battery,
> are we any better off? If you're going to accept a large live wire
> running along the fuselage, will it help that the 2 AWG is cold and the
> 4 AWG is hot? Might as well just leave the 2 AWG hot and move the relay
> to the front as you first described.
>
> The only other solutions I can think of are
>
> 1. Relays on both wires and dual fed engine and aux busses. In a forced
> landing you shut off both relays.
> 2. A second battery in the engine compartment.
> 3. A second alternator and feed your dual fed engine and aux busses from
> each alternator, dropping the battery feed.
>
> On Sat, Sep 4, 2021 at 2:10 PM A Lumley <andrew.lumley(at)sympatico.ca (andrew.lumley(at)sympatico.ca)
> <mailto:andrew.lumley(at)sympatico.ca (andrew.lumley(at)sympatico.ca)>> wrote:
>
>     --> AeroElectric-List message posted by: "A Lumley"
>     <andrew.lumley(at)sympatico.ca (andrew.lumley(at)sympatico.ca) <mailto:andrew.lumley(at)sympatico.ca (andrew.lumley(at)sympatico.ca)>>
>
>     I'm in Belleville, 2 hours from Toronto.
>
>     The hot battery bus itself is only about 0.5 amps for a few overhead
>     lights. The issue is that the Z-101 schematic has the ability to
>     power the aux and engine busses through relays attached to the
>     battery side of the battery contactor. My engine bus will draw 15-20
>     amps (SDS EFI) when both fuel pumps are running. The Aux bus
>     includes the PFD, GPS, pitot heat, autopilot, and a few other small
>     loads that will total another 15-20 amps with the pitot heat operating.
>
>     I'm thinking I'll need a separate cable of about 4 AWG running
>     forward from the battery in addition to the 2 AWG starter cable.
>     Just wondering if there is a better way, perhaps not.
>
>
>
>
>     Read this topic online here:
>
>     http://forums.matronics.com/viewtopic.php?p=503043#503043
>     <http://forums.matronics.com/viewtopic.php?p=503043#503043>
>
>
>
>
>
>
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