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Dual batteries or dual alternators?
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erich weaver



Joined: 16 Jun 2016
Posts: 11

PostPosted: Mon Jun 20, 2016 1:55 pm    Post subject: Dual batteries or dual alternators? Reply with quote

Hello Bob

Over on another popular forum, there was recently a discussion on whether it was preferable to have an electrical system with two batteries or with two alternators. Having previously read the Aeroelectric Connection and followed your forum here, my 2 cents worth would advocate for two alternators, as this provides unlimited duration backup; however, many disagreed. In particular, the owner of EFII (www.flyefii.com) said the following:

"Electrical system complexity follows a progression:
1. One batt, one alternator
2. Two batts, one alternator
3. Two batts, two alternators

One batt, two alternators is a problem. If you lose the batt, all you have left is half wave rectified AC power off the alternator - this means unhappy electronics. There needs to be a functioning battery in the system to absorb the pulses from the alternator."

I feel pretty confident that if my battery successfully starts my engine that I am unlikely to "lose the battery" during a flight, and I also have some doubts about the need for a battery to absorb pulses from the alternator.

Don't want to start any war of the experts here, but I would welcome your comment, and may repost your reply to the other forum as a followup, as many do respect your opinion.

Best regards,

Erich


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PostPosted: Mon Jun 20, 2016 2:34 pm    Post subject: Dual batteries or dual alternators? Reply with quote

Are you referring to the Vans forums?

Quote:
On Jun 20, 2016, at 17:55, erich weaver <erich.weaver(at)aecom.com> wrote:



Hello Bob

Over on another popular forum, there was recently a discussion on whether it was preferable to have an electrical system with two batteries or with two alternators. Having previously read the Aeroelectric Connection and followed your forum here, my 2 cents worth would advocate for two alternators, as this provides unlimited duration backup; however, many disagreed. In particular, the owner of EFII (www.flyefii.com) said the following:

"Electrical system complexity follows a progression:
1. One batt, one alternator
2. Two batts, one alternator
3. Two batts, two alternators

One batt, two alternators is a problem. If you lose the batt, all you have left is half wave rectified AC power off the alternator - this means unhappy electronics. There needs to be a functioning battery in the system to absorb the pulses from the alternator."

I feel pretty confident that if my battery successfully starts my engine that I am unlikely to "lose the battery" during a flight, and I also have some doubts about the need for a battery to absorb pulses from the alternator.

Don't want to start any war of the experts here, but I would welcome your comment, and may repost your reply to the other forum as a followup, as many do respect your opinion.

Best regards,

Erich


Quote:



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PostPosted: Mon Jun 20, 2016 2:49 pm    Post subject: Dual batteries or dual alternators? Reply with quote

Erich,

I have a single battery dual alternator system wired like Bobs Z 13-8. I fly in Remote Alaska and have the Dual ECU EFII system. Twice now I have run into alternator trouble on a remote gravel bar 2 hours from civilization.

Once was a bad primary alternator and the next time was a pulley that came off the primary alternator. In both cases, I didn't have use of the primary alternator. Had I not had a secondary alternator. On the vacuum pad, I would not have been able to depart because I wouldn't have safely had the battery longevity to fly to civilization. I would have had to have someone fly parts out.

Since I had a secondary alternator, I switched off the primary, switched on the secondary, and flew home safely.

I have no regrets and I am happy that I went with this architecture and Bob has been more than helpful and displays masterful knowledge.

Hope this helps.

Justin.
Quote:
On Jun 20, 2016, at 17:55, erich weaver <erich.weaver(at)aecom.com> wrote:



Hello Bob

Over on another popular forum, there was recently a discussion on whether it was preferable to have an electrical system with two batteries or with two alternators. Having previously read the Aeroelectric Connection and followed your forum here, my 2 cents worth would advocate for two alternators, as this provides unlimited duration backup; however, many disagreed. In particular, the owner of EFII (www.flyefii.com) said the following:

"Electrical system complexity follows a progression:
1. One batt, one alternator
2. Two batts, one alternator
3. Two batts, two alternators

One batt, two alternators is a problem. If you lose the batt, all you have left is half wave rectified AC power off the alternator - this means unhappy electronics. There needs to be a functioning battery in the system to absorb the pulses from the alternator."

I feel pretty confident that if my battery successfully starts my engine that I am unlikely to "lose the battery" during a flight, and I also have some doubts about the need for a battery to absorb pulses from the alternator.

Don't want to start any war of the experts here, but I would welcome your comment, and may repost your reply to the other forum as a followup, as many do respect your opinion.

Best regards,

Erich




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erich weaver



Joined: 16 Jun 2016
Posts: 11

PostPosted: Mon Jun 20, 2016 3:06 pm    Post subject: Re: Dual batteries or dual alternators? Reply with quote

All makes sense to me Justin; I followed the Z-13/8 architecture as well on my RV-7A. Yes, original post was on the VAF forum. Just a bit surprised by the response from EFII.

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PostPosted: Mon Jun 20, 2016 3:45 pm    Post subject: Dual batteries or dual alternators? Reply with quote

Surprised indeed.
I've never seen an alternator that normally put out "half wave rectified
power" and I have seen automotive EFI systems run fine with a
disconnected battery.

There have been cases of some alternators going offline when overloaded
to the point where the voltage drops way off but that isn't going to
happen with a PM alternator. I'd want to suss out that scenario though
with the alternator of choice if there are any heavy loads in the
aircraft. I just used two tiny Dekka batteries that together weigh the
same as the popular odysey battery and called it done. One has been in
use for 10 years and the other 9 years now which for me makes the
economics darn good compared to maintaining a single larger battery.
Ken

On 20/06/2016 7:06 PM, erich weaver wrote:
Quote:


All makes sense to me Justin; I followed the Z-13/8 architecture as well on my RV-7A. Yes, original post was on the VAF forum. Just a bit surprised by the response from EFII.


Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=457325#457325



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user9253



Joined: 28 Mar 2008
Posts: 1907
Location: Riley TWP Michigan

PostPosted: Mon Jun 20, 2016 3:52 pm    Post subject: Re: Dual batteries or dual alternators? Reply with quote

Can not argue with the order of complexity. As for which architecture is best, it is a matter of personal preference. A battery failing in flight is unlikely. Even if it did, how would you know it? What are the symptoms? If the pilot correctly identifies a battery failure, what is the correct action to take and why? I question the statement, "all you have left is half wave rectified AC power off the alternator". Most alternators put out rectified 3-phase full-wave current, not half wave DC. I agree with your statement, "I also have some doubts about the need for a battery to absorb pulses from the alternator." Our electrical guru has stated that avionics should be designed to handle anything an aircraft electrical system can throw at it.
The ideal electrical system will keep critical equipment functioning even if a failure occurs and without requiring any action by the pilot, except to make a note to do repairs after landing.


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PostPosted: Mon Jun 20, 2016 5:20 pm    Post subject: Dual batteries or dual alternators? Reply with quote

Robert at EFII wants you to use his bus manager. It's an additional $600-800 and can't handle 2 alternators. Its economically advantageous for him to recommend a system that works with his bus manager.

I don't want to sound like I'm trash talking Robert here. I'm not. He has incredible customer service and is a stand up guy!

Justin

Quote:
On Jun 20, 2016, at 18:06, erich weaver <erich.weaver(at)aecom.com> wrote:



All makes sense to me Justin; I followed the Z-13/8 architecture as well on my RV-7A. Yes, original post was on the VAF forum. Just a bit surprised by the response from EFII.




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http://forums.matronics.com/viewtopic.php?p=457325#457325












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kenryan



Joined: 20 Oct 2009
Posts: 424

PostPosted: Mon Jun 20, 2016 5:34 pm    Post subject: Dual batteries or dual alternators? Reply with quote

If you want the EFII Bus Manager set up for two alternators, you can get it that way. It can indeed "handle two alternators."

On Mon, Jun 20, 2016 at 5:18 PM, Justin Jones <jmjones2000(at)mindspring.com (jmjones2000(at)mindspring.com)> wrote:
Quote:
--> AeroElectric-List message posted by: Justin Jones <jmjones2000(at)mindspring.com (jmjones2000(at)mindspring.com)>

Robert at EFII wants you to use his bus manager. It's an additional $600-800 and can't handle 2 alternators. Its economically advantageous for him to recommend a system that works with his bus manager.

I don't want to sound like I'm trash talking Robert here. I'm not. He has incredible customer service and is a stand up guy!

Justin

> On Jun 20, 2016, at 18:06, erich weaver <erich.weaver(at)aecom.com (erich.weaver(at)aecom.com)> wrote:
>
> --> AeroElectric-List message posted by: "erich weaver" <erich.weaver(at)aecom.com (erich.weaver(at)aecom.com)>
>
> All makes sense to me Justin;  I followed the Z-13/8 architecture as well on my RV-7A. Yes, original post was on the VAF forum.  Just a bit surprised by the response from EFII.
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=457325#457325
>
>
>
>
>
>
>
>
>
>



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PostPosted: Mon Jun 20, 2016 5:54 pm    Post subject: Dual batteries or dual alternators? Reply with quote

Good to know. Thanks Ken. It doesn't show this on the manuals available online

On Jun 20, 2016, at 20:33, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
Quote:
If you want the EFII Bus Manager set up for two alternators, you can get it that way. It can indeed "handle two alternators."

On Mon, Jun 20, 2016 at 5:18 PM, Justin Jones <jmjones2000(at)mindspring.com (jmjones2000(at)mindspring.com)> wrote:
Quote:
--> AeroElectric-List message posted by: Justin Jones <jmjones2000(at)mindspring.com (jmjones2000(at)mindspring.com)>

Robert at EFII wants you to use his bus manager. It's an additional $600-800 and can't handle 2 alternators. Its economically advantageous for him to recommend a system that works with his bus manager.

I don't want to sound like I'm trash talking Robert here. I'm not. He has incredible customer service and is a stand up guy!

Justin

> On Jun 20, 2016, at 18:06, erich weaver <erich.weaver(at)aecom.com (erich.weaver(at)aecom.com)> wrote:
>
> --> AeroElectric-List message posted by: "erich weaver" <erich.weaver(at)aecom.com (erich.weaver(at)aecom.com)>
>
> All makes sense to me Justin; I followed the Z-13/8 architecture as well on my RV-7A. Yes, original post was on the VAF forum. Just a bit surprised by the response from EFII.
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=457325#457325
>
>
>
>
>
>
>
>
>
>



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kenryan



Joined: 20 Oct 2009
Posts: 424

PostPosted: Mon Jun 20, 2016 6:04 pm    Post subject: Dual batteries or dual alternators? Reply with quote

I've got one that has never been used (that I am not using) if anybody is looking for a good price Smile When I bought mine it was an either/or on the two alternator set up, but Robert said the next run would have a jumper so that it could be used either way (one alternator or two). I don't know if that has happened yet or not.

On Mon, Jun 20, 2016 at 5:52 PM, Justin Jones <jmjones2000(at)mindspring.com (jmjones2000(at)mindspring.com)> wrote:
Quote:

Good to know. Thanks Ken. It doesn't show this on the manuals available online 

On Jun 20, 2016, at 20:33, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
Quote:
If you want the EFII Bus Manager set up for two alternators, you can get it that way. It can indeed "handle two alternators."

On Mon, Jun 20, 2016 at 5:18 PM, Justin Jones <jmjones2000(at)mindspring.com (jmjones2000(at)mindspring.com)> wrote:
Quote:
--> AeroElectric-List message posted by: Justin Jones <jmjones2000(at)mindspring.com (jmjones2000(at)mindspring.com)>

Robert at EFII wants you to use his bus manager. It's an additional $600-800 and can't handle 2 alternators. Its economically advantageous for him to recommend a system that works with his bus manager.

I don't want to sound like I'm trash talking Robert here. I'm not. He has incredible customer service and is a stand up guy!

Justin

> On Jun 20, 2016, at 18:06, erich weaver <erich.weaver(at)aecom.com (erich.weaver(at)aecom.com)> wrote:
>
> --> AeroElectric-List message posted by: "erich weaver" <erich.weaver(at)aecom.com (erich.weaver(at)aecom.com)>
>
> All makes sense to me Justin;  I followed the Z-13/8 architecture as well on my RV-7A. Yes, original post was on the VAF forum.  Just a bit surprised by the response from EFII.
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=457325#457325
>
>
>
>
>
>
>
>
>
>



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PostPosted: Mon Jun 20, 2016 6:26 pm    Post subject: Dual batteries or dual alternators? Reply with quote

Robert may take yours and modify it for you. He is an awesome guy and I'm beyond satisfied with the EFII products and his customer service!

On Jun 20, 2016, at 21:03, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
Quote:
I've got one that has never been used (that I am not using) if anybody is looking for a good price Smile When I bought mine it was an either/or on the two alternator set up, but Robert said the next run would have a jumper so that it could be used either way (one alternator or two). I don't know if that has happened yet or not.

On Mon, Jun 20, 2016 at 5:52 PM, Justin Jones <jmjones2000(at)mindspring.com (jmjones2000(at)mindspring.com)> wrote:
Quote:

Good to know. Thanks Ken. It doesn't show this on the manuals available online

On Jun 20, 2016, at 20:33, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
Quote:
If you want the EFII Bus Manager set up for two alternators, you can get it that way. It can indeed "handle two alternators."

On Mon, Jun 20, 2016 at 5:18 PM, Justin Jones <jmjones2000(at)mindspring.com (jmjones2000(at)mindspring.com)> wrote:
Quote:
--> AeroElectric-List message posted by: Justin Jones <jmjones2000(at)mindspring.com (jmjones2000(at)mindspring.com)>

Robert at EFII wants you to use his bus manager. It's an additional $600-800 and can't handle 2 alternators. Its economically advantageous for him to recommend a system that works with his bus manager.

I don't want to sound like I'm trash talking Robert here. I'm not. He has incredible customer service and is a stand up guy!

Justin

> On Jun 20, 2016, at 18:06, erich weaver <erich.weaver(at)aecom.com (erich.weaver(at)aecom.com)> wrote:
>
> --> AeroElectric-List message posted by: "erich weaver" <erich.weaver(at)aecom.com (erich.weaver(at)aecom.com)>
>
> All makes sense to me Justin; I followed the Z-13/8 architecture as well on my RV-7A. Yes, original post was on the VAF forum. Just a bit surprised by the response from EFII.
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=457325#457325
>
>
>
>
>
>
>
>
>
>



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PostPosted: Mon Jun 20, 2016 8:59 pm    Post subject: Dual batteries or dual alternators? Reply with quote

At 06:06 PM 6/20/2016, you wrote:
Quote:
--> AeroElectric-List message posted by: "erich weaver" <erich.weaver(at)aecom.com>

All makes sense to me Justin; I followed the Z-13/8 architecture as well on my RV-7A. Yes, original post was on the VAF forum. Just a bit surprised by the response from EFII.

. . . which was?


Bob . . .


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PostPosted: Mon Jun 20, 2016 9:16 pm    Post subject: Dual batteries or dual alternators? Reply with quote

At 04:55 PM 6/20/2016, you wrote:
Quote:
--> AeroElectric-List message posted by: "erich weaver" <erich.weaver(at)aecom.com>

Hello Bob

Over on another popular forum, there was recently a discussion on whether it was preferable to have an electrical system with two batteries or with two alternators. Having previously read the Aeroelectric Connection and followed your forum here, my 2 cents worth would advocate for two alternators, as this provides unlimited duration backup; however, many disagreed. In particular, the owner of EFII (www.flyefii.com) said the following:

"Electrical system complexity follows a progression:
1. One batt, one alternator
2. Two batts, one alternator
3. Two batts, two alternators

One batt, two alternators is a problem. If you lose the batt, all you have left is half wave rectified AC power off the alternator - this means unhappy electronics. There needs to be a functioning battery in the system to absorb the pulses from the alternator."

I feel pretty confident that if my battery successfully starts my engine that I am unlikely to "lose the battery" during a flight, and I also have some doubts about the need for a battery to absorb pulses from the alternator.

Okay, this is easy . . .

A battery SHOULD be the most reliable source of energy
in your airplane. Simple, no moving parts, easy to quantify
for performance.

Any time I've had a customer cite a battery 'failure',
I've had to ask, "What was the last cap check you did . . .
and how long ago?"

Like tires, oil and even propellers . . . the battery
is a commodity. It is subject to stresses of environment
and circumstance. Yet unlike tires and props that get
pre-flight check and oil that gets changed out every so
many hours . . . batteries tend to be treated in airplanes
like they do in our cars. Run 'em until they don't crank
the engine any more.

A battery that fails to get your engine started has
been essentially USELESS as back-up energy source for
a long time.

Z-13/8 was crafted with the notion that the SD-8
alternator was NOT installed to back up DUAL failures
of main alternator AND a battery . . . but simply to
run 8A or LESS of endurance loads after a single failure
of the main alternator. The idea was to hold all the
battery's contained energies in RESERVE for descent
and approach to landing.

If one is crafting a plan-B, plan-C or any other
plan assuming that alternators are there to back up
a failed battery simply does not appreciate the need
for KNOWING that your prop leading edges, alternator
drive belt, tires, oil levels AND BATTERY are ready
to deliver to mission requirements.

A battery that fails cap check for minimum battery
only endurance probably cranks the engine just fine. Getting
the engine started is NOT a substitute for battery
cap check. Z-13/8, when operated within its design
goals, gives you as much mission reliability as any
other architecture.

The biggest advantage of Z-13/8 is savings in WEIGHT.
A 3 pound alternator gives you unlimited endurance
at e-bus loads of 10A or less thus holding the battery
completely in reserve . . . which should allow you to
arrive at the airport of intended destination with
lights a-blazing and all the screens lit up in
vivid colors.

It's all about energy management and preventative
maintenance.



Bob . . .


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PostPosted: Mon Jun 20, 2016 9:18 pm    Post subject: Dual batteries or dual alternators? Reply with quote

At 06:44 PM 6/20/2016, you wrote:
Quote:
--> AeroElectric-List message posted by: C&K <yellowduckduo(at)gmail.com>

Surprised indeed.
I've never seen an alternator that normally put out "half wave rectified power" and I have seen automotive EFI systems run fine with a disconnected battery.

The SD-8 is a single phase output with considerable
'trash' on the output . . .


Quote:
There have been cases of some alternators going offline when overloaded to the point where the voltage drops way off but that isn't going to happen with a PM alternator. I'd want to suss out that scenario though with the alternator of choice if there are any heavy loads in the aircraft. I just used two tiny Dekka batteries that together weigh the same as the popular odysey battery and called it done. One has been in use for 10 years and the other 9 years now which for me makes the economics darn good compared to maintaining a single larger battery.
What did your batteries do at the last cap check?



Bob . . .


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nuckolls.bob(at)aeroelect
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PostPosted: Mon Jun 20, 2016 9:27 pm    Post subject: Dual batteries or dual alternators? Reply with quote

At 06:52 PM 6/20/2016, you wrote:
Quote:
--> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com>

Can not argue with the order of complexity. As for which architecture is best, it is a matter of personal preference.

How is parts count x weight x cost of ownership to achieve
the highest practical system reliability a matter of
'personal preferences'?

Quote:
A battery failing in flight is unlikely. Even if it did, how would you know it? What are the symptoms? If the pilot correctly identifies a battery failure, what is the correct action to take and why? I question the statement, "all you have left is half wave rectified AC power off the alternator". Most alternators put out rectified 3-phase full-wave current, not half wave DC. I agree with your statement, "I also have some doubts about the need for a battery to absorb pulses from the alternator." Our electrical guru has stated that avionics should be designed to handle anything an aircraft electrical system can throw at it.
The ideal electrical system will keep critical equipment functioning even if a failure occurs and without requiring any action by the pilot, except to make a note to do repairs after landing.

Exactly. Check out the DAS plots for SD-8 output
under various combinations of load, battery and
presence of a 'filter' capacitor at:

http://www.aeroelectric.com/Pictures/Curves/Alternator_Performance/SD-8_Noise-Plots/SD-8_Noise_Data.pdf

In particular, page 8 where an SD-8 is operated
with a 47Kuf capacitor, NO battery, and 8.8A
load while supporting a 14.5v bus.

Note that ripple was 129 mv pk-pk and 38mv RMS.

My question of any detractors of SD-8 operations
would be, what is it about the quality of this
output that is deleterious to your product?


Bob . . .


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nuckolls.bob(at)aeroelect
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PostPosted: Mon Jun 20, 2016 9:35 pm    Post subject: Dual batteries or dual alternators? Reply with quote

At 09:25 PM 6/20/2016, you wrote:
Quote:
Robert may take yours and modify it for you. He is an awesome guy and I'm beyond satisfied with the EFII products and his customer service!
Quote:

I would be interested to know how system reliability
is improved by any process that goes beyond running
all engine dependent components directly from a
battery bus . . . as a general rule, system reliability
DOES NOT improve with increased in parts count or
operational complexity.

All too often, system integrators get wrapped around
the "keep it powered up at all costs" axle while loosing
sight of vulnerabilities of the electrically dependent
device or system.

The LA-IFP accident

http://www.aeroelectric.com/Reference_Docs/Accidents/N811HB_Feb2008_LA-IVp/

is one such example. The guy was so worried about keeping
BOTH ignition systems powered up that he lost sight
of both single points of failure and loss of integrity
due to poor architecture.




Bob . . .


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EFII



Joined: 27 Feb 2016
Posts: 1
Location: Southern California

PostPosted: Mon Jun 27, 2016 11:43 am    Post subject: EFII Bus Manager Reply with quote

Hi Bob and everyone else,
Here is our take on the Bus Manager:
We wanted a simple one box solution to provide the management necessary for a two battery setup to support electronically dependent engines. The creation of a protected "Essential Bus" being the primary goal. The Essential Bus is the protected power source for the engine electronics.

We also wanted some other items such as: Battery charge isolation, ability to start the engine off of either battery (or both), and automatic management of a dual electric fuel pump module.

The Bus Manager is simply the solution for the above requirement.
It does not require pilot intervention to supply current from either battery to the Essential Bus. It also does not require pilot intervention to engage the backup electric fuel pump.

In addition, there is a third level of redundancy via the Emergency Power switch. There is a Main Bus output powered by the primary battery to power non-flight critical systems. The Bus Manager also supports one or two alternator operation. Most two seat airplanes can use two Odyssey PC625 batteries for the system. Two of these batteries together are similar in size and weight to one Concord (RG-25) aircraft battery.

The failure mode the we have seen most in small aircraft is simply a loose wire somewhere. If the loose wire happens to be a battery cable or primary bus supply wire, this can spell trouble for the engine electronics. Having multiple paths for electricity to reach critical equipment is the simple solution to this issue. An architecture that allows the backup process to occur without pilot intervention means that the engine never skips a beat if one supply source goes down - this is a big deal and provides a big comfort level. I have witnessed an entire panel go black and the Bus Manager protect the engine without power interruption.

Anyhow, those are the goals of the Bus Manager. It is a simple one-box solution to a semi complicated problem. In most experimentals, the Bus Manager can provide the the power distribution for the entire plane. It really makes power system setup a simple task. And simple means reliable.
Robert Paisley
EFII


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Flying Patagonia



Joined: 03 Oct 2017
Posts: 4

PostPosted: Wed Oct 04, 2017 5:08 am    Post subject: Re: Dual batteries or dual alternators? Reply with quote

Hello to everybody, does anyone have the best diagram for installing the dual EFII, with two alternators and single battery??
And second question, how would be the wiring with the bus manager using 2 alt and single battery


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user9253



Joined: 28 Mar 2008
Posts: 1907
Location: Riley TWP Michigan

PostPosted: Wed Oct 04, 2017 7:03 am    Post subject: Re: Dual batteries or dual alternators? Reply with quote

The best wiring diagram is the simplest one. Look at Bob's diagrams
http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/
and pick one that is close to what you want. Then modify it as needed for your system. Save yourself $600 by NOT buying a bus manager.


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kenryan



Joined: 20 Oct 2009
Posts: 424

PostPosted: Wed Oct 04, 2017 7:48 am    Post subject: Dual batteries or dual alternators? Reply with quote

It used to be that there were two versions of the bus manager, depending on whether the system has one or two charging devices. Robert Paisley said he had plans to modify the design so that it would work with either one or two by setting a jumper. I don't know if he ever did that or not. 
Sent from my Android. Sorry Steve.

On Oct 4, 2017 5:15 AM, "Flying Patagonia" <tintiescobar(at)hotmail.com (tintiescobar(at)hotmail.com)> wrote:
Quote:
--> AeroElectric-List message posted by: "Flying Patagonia" <tintiescobar(at)hotmail.com (tintiescobar(at)hotmail.com)>

Hello to everybody, does anyone have the best diagram for installing the dual EFII, with two alternators and single battery??
And second question, how would be the wiring with the bus manager using 2 alt and single battery




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