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Please critique my electrical design
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N884RA



Joined: 22 Mar 2018
Posts: 6

PostPosted: Tue Apr 10, 2018 3:55 am    Post subject: Please critique my electrical design Reply with quote

I've been working on the electrical architecture for my RV-8 and I'm getting close to a solution, but before I start buying and installing components, I'd like to get some feedback on my deign.

I'm planning an IFR-capable RV-8 with a Titan IO-370, dual P-mags and a Whirlwind constant speed prop. Avionics will be the G3X system with G-5, GTN-650, GTR20, et al. I'm planning to use the Earth-X ETX680 battery as the main, and a TCW 3 Ah backup battery. The main alternator will be a belt-driven B&C BC-460H (60 Amps) with a gear-driven SD-8 backup (<8 Amps).

I've read Bob Nuckolls book several times and I'm sold on two alternator one battery set up he described in Z-13. My architecture is based on that, and only has minor changes such as addition of avionics switch, dual P-mags, deletion of the low voltage package (G3X has that feature), and addition of a back-up battery.

Here's a link to my design: https://www.dropbox.com/s/2l10pzbcba4z4k7/Electrical%20System%20Overview%20%28v13.11%29.pdf?dl=0

I've come up with a battery buss, main busses and endurance busses. Main Bus has been divided into three: MB1 is fuses, MB2 is circuit breakers, and MB3 is a planned expansion of an additional fuse block. (I gave this block a load of 5 amps as a planning figure.) I won't construct it, but I will have a place to put it in case I need it in the future. Essential Buss 1 is fuses, and EB2 is CBs. I've mostly used fuses, except for a few items where I want to be able to use the fuse as an alternate means of disconnecting power to an appliance, or where the manufactures specify a CB.

I've worked tirelessly on my load analysis, and I think it's pretty solid. I've had to make some assumptions of appliance power requirements when I couldn't find the exact power requirements of a particular unit.

I've used the "Night IFR" load analysis for my continuous flow value, and "Typical Max" load as my intermittent flow value when doing my analysis for sizing wires, using figures 11-2 in AC 43.13 as a reference.

I welcome any comments, suggestion or critiques of my design.

Thanks for looking.
Rob


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PostPosted: Tue Apr 10, 2018 7:15 am    Post subject: Please critique my electrical design Reply with quote

At 06:55 AM 4/10/2018, you wrote:
Quote:
--> AeroElectric-List message posted by: "N884RA" <n884ra(at)gmail.com>

I've been working on the electrical architecture for my RV-8 and I'm getting close to a solution, but before I start buying and installing components, I'd like to get some feedback on my deign.

I'm planning an IFR-capable RV-8 with a Titan IO-370, dual P-mags and a Whirlwind constant speed prop. Avionics will be the G3X system with G-5, GTN-650, GTR20, et al. I'm planning to use the Earth-X ETX680 battery as the main, and a TCW 3 Ah backup battery. The main alternator will be a belt-driven B&C BC-460H (60 Amps) with a gear-driven SD-8 backup (


the very first example of Z13/8 to fly was in an RV8.
Lost contact with the builders out in CT about 10 years
ago . . . but the system had hundreds of hours on it
then and the builders were delighted with the performance.

The larger standby alternator suggests Z12 which has
also been incorporated on a fleet of OBAM aircraft
and hundreds of TC aircraft.

With two alternators, why a backup battery?



Bob . . .


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N884RA



Joined: 22 Mar 2018
Posts: 6

PostPosted: Tue Apr 10, 2018 7:48 am    Post subject: Re: Please critique my electrical design Reply with quote

Bob,

Thanks for the response -- it's a pleasure to dialog with you after having spent so much time reading and rereading your book.

The backup batter is a TCW IBBS-12v-3ah battery, and it's recommended by Garmin to keep the G3X and engine interface on through the voltage drop during engine start. Since the G3X is the only engine instrumentation I have, that seems like a key component.

My standby alternator is an SD-8, which I think is what you designed the Z-13/8T around, correct? It provides me with enough power for my en route phase except when transmitting on the radio with the autopilot engaged, but I think that's a reasonable tradeoff for the simplicity and value of the Z-13.

Your latest Z-13/8 didn't have dual P-mags on it, so I wanted to make sure what I've done is acceptable. I initially had both P-mags on my Main Bus 2, but another builder recommended splitting the sources for redundancy in the event of a main alternator failure, even though splitting their sources adds an extra wire run from the Battery Bus (near the battery) to the CB & switch. Given the length of that run, I thought it should have a fuse, even though the P-mag install instructions call for a 3A CB. I sent a query to Emag this morning to ask for their input on that and my current setup of fuse -- CB -- switch -- P-mag.

I also incorporated your suggested avionics switch for those who have to have one. I know you're not fond of CB switches, but I couldn't find a switch rated for 30A that wasn't a CB. Would a relay be better in lieu of the CB switch? (Main Bus 1 and Endurance Bus 1 are located a couple inches from each other.)

Thanks again!
Rob


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Last edited by N884RA on Tue Apr 10, 2018 5:01 pm; edited 1 time in total
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N884RA



Joined: 22 Mar 2018
Posts: 6

PostPosted: Tue Apr 10, 2018 9:14 am    Post subject: Re: Please critique my electrical design Reply with quote

I heard back from EMAG today and they recommended the following:

Quote:

The P-mags should be put on the main bus because we only require a battery for starting. After 800 RPM or so we switch to running off our internal generator and do not require an external source. In the event of an internal generator failure we would switch back to the external power (main bus). Be sure to do the minimum cut-out test to see where the ignitions drop off and note it so in the event of an alternator failure you wont run the risk of the having to low of RPM for our ignitions to continue sparking.

If you do put us on the battery directly you run the chance of leaving us on and draining your battery.


I've updated my design to put the P-mags back the way I initially had them and removed the Battery Bus fuse block once again. That leads me to a new question -- is a 30A inline fuse too large for that device? Should I use a current limiter instead, or a CB in the engine compartment?

Thanks,
Rob


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Last edited by N884RA on Tue Apr 10, 2018 9:24 am; edited 1 time in total
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user9253



Joined: 28 Mar 2008
Posts: 1163
Location: Riley TWP Michigan

PostPosted: Tue Apr 10, 2018 9:22 am    Post subject: Re: Please critique my electrical design Reply with quote

The main voltage regulator sense terminal (3?) should
connect to the to the main power bus and not share a wire
with the field current. The way it is connected now will
eventually lead to overvoltage conditions due to
increasing resistance as terminals and switch contacts
corrode over time.
The start switch does not need to be on a circuit
breaker. A fuse on the main power bus should never blow.
And if it did, there should be a good reason.
And the plane will be safely on the ground if and
when the start fuse does blow.
There should not be 2 fuselinks in series going to the
main alternator field breaker. One is good enough. The
second one is redundant.
Who knows if the aux alt 2 amp breaker will trip before
the 15 amps fuse blows. Maybe increase the fuse to 30
amps?
Consider doing away with the avionics switch.
Maybe the trim indicator and fuel gauge should be on the
endurance bus. They use very little power.


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Joe Gores
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BARRY CHECK 6



Joined: 15 Mar 2011
Posts: 620

PostPosted: Tue Apr 10, 2018 12:03 pm    Post subject: Please critique my electrical design Reply with quote

Quote:

 With two alternators, why a backup battery?



  Bob . . .


​Because what if the battery fails?
G-5's can have the Garmin $150 TINNY battery or ​you can apply that money to a much larger second battery which will be big enough to start the plane and supply days of power for the G-5.  I have not installed the G-3,  but I have installed 2 planes with Dual G-5's (AI & HSI).  With dual G-5's in a certified plane you are required to 
have dual Garmin batteries...  That is $300 for a stinking 1 or 2 AH battery.  Yea, I would be very happy to install a second battery - a small one - With just enough to start the plane in a 24:00 DARK stranded situation.  
Yea, happened to me one night.  No Fun!
Barry


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PostPosted: Tue Apr 10, 2018 12:46 pm    Post subject: Please critique my electrical design Reply with quote

At 03:01 PM 4/10/2018, you wrote:

Quote:
With two alternators, why a backup battery?


Bob . . .


​Because what if the battery fails?
G-5's can have the Garmin $150 TINNY battery or ​you can apply that money to a much larger second battery which will be big enough to start the plane and supply days of power for the G-5. I have not installed the G-3, but I have installed 2 planes with Dual G-5's (AI & HSI). With dual G-5's in a certified plane you are required to
have dual Garmin batteries... That is $300 for a stinking 1 or 2 AH battery. Yea, I would be very happy to install a second battery - a small one - With just enough to start the plane in a 24:00 DARK stranded situation.
Yea, happened to me one night. No Fun!

Barry

Was this in spite of a considered preventative
maintenance program? What was the battery's last
cap-check value before the failure?

A battery that is watched and maintained as
carefully as tires, belts, propeller nicks
air cleaners and engine oil is very unlikely
to fail. Dual alternators virtually assures
you of engine driven energy in spite of the
loss of one alternator.

The rule of thumb for battery replacement
in the TC world is when it falls to less than
75% of original capacity . . . in the modern
RG battery world, this means it probably
still cranks the engine but is in substantial
decline on an ever increasing slope to failure
yet unlikely to go belly up away from your
home hangar.

Few light aircraft owner's manuals speak to
affirmative-action maintenance programs . . .
but I'd bet that top-billing in the cast of performers
virtually all dark-n-stormy night stories that
speak to battery failure is a beyond-service-life
battery.




Bob . . .


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BARRY CHECK 6



Joined: 15 Mar 2011
Posts: 620

PostPosted: Tue Apr 10, 2018 3:15 pm    Post subject: Please critique my electrical design Reply with quote

Bob:
Let's get a show of hands...
How many Pilots out there have a LOAD tester?
I can't get owners to check their tires and you want them to load test a battery!
Granted!  This is a aero-electric email list and many are builders.  So, if there are fellows out there that do have a load tester I doubt that would cover the rest of the BUYERS that only purchased the plane and did not build.
What do you think would sell a plane faster:
'Oh, and this plane has Dual Alternators and Dual Batteries.'
Or...
'And every year at annual I Load Test the battery."
Barry


On Tue, Apr 10, 2018 at 4:44 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
Quote:
At 03:01 PM 4/10/2018, you wrote:

Quote:
 With two alternators, why a backup battery?


  Bob . . .


​Because what if the battery fails?
G-5's can have the Garmin $150 TINNY battery or ​you can apply that money to a much larger second battery which will be big enough to start the plane and supply days of power for the G-5.  I have not installed the G-3,  but I have installed 2 planes with Dual G-5's (AI & HSI).  With dual G-5's in a certified plane you are required toÂ
have dual Garmin batteries...  That is $300 for a stinking 1 or 2 AH battery.  Yea, I would be very happy to install a second battery - a small one - With just enough to start the plane in a 24:00 DARK stranded situation. Â
Yea, happened to me one night.  No Fun!

Barry

  Was this in spite of a considered preventative
  maintenance program? What was the battery's last
  cap-check value before the failure?

  A battery that is watched and maintained as
  carefully as tires, belts, propeller nicks
  air cleaners and engine oil is very unlikely
  to fail. Dual alternators virtually assures
  you of engine driven energy in spite of the
  loss of one alternator.

  The rule of thumb for battery replacement
  in the TC world is when it falls to less than
  75% of original capacity . . . in the modern
  RG battery world, this means it probably
  still cranks the engine but is in substantial
  decline on an ever increasing slope to failure
  yet unlikely to go belly up away from your
  home hangar.

  Few light aircraft owner's manuals speak to
  affirmative-action maintenance programs . . .
  but I'd bet that top-billing in the cast of performers
  virtually all dark-n-stormy night stories that
  speak to battery failure is a beyond-service-life
  battery.
 



  Bob . . .


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rene(at)felker.com
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PostPosted: Tue Apr 10, 2018 3:35 pm    Post subject: Please critique my electrical design Reply with quote

I do not know about what sells…..but I have mine load tested at Batteries +.

I have two batteries and two alternators.  I have one battery that is 10+ years and the other is about 5 now.  I had two battery failures….one self induced and the other was infant mortality.

Rene'
801-721-6080

From: owner-aeroelectric-list-server(at)matronics.com <owner-aeroelectric-list-server(at)matronics.com> On Behalf Of FLYaDIVE
Sent: Tuesday, April 10, 2018 5:15 PM
To: aeroelectric-list(at)matronics.com
Subject: Re: Please critique my electrical design

Bob:



Let's get a show of hands...

How many Pilots out there have a LOAD tester?

I can't get owners to check their tires and you want them to load test a battery!

Granted! This is a aero-electric email list and many are builders. So, if there are fellows out there that do have a load tester I doubt that would cover the rest of the BUYERS that only purchased the plane and did not build.

What do you think would sell a plane faster:

'Oh, and this plane has Dual Alternators and Dual Batteries.'

Or...

'And every year at annual I Load Test the battery."



Barry



On Tue, Apr 10, 2018 at 4:44 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
Quote:

At 03:01 PM 4/10/2018, you wrote:
Quote:

 With two alternators, why a backup battery?
 Bob . . .

​Because what if the battery fails?
G-5's can have the Garmin $150 TINNY battery or ​you can apply that money to a much larger second battery which will be big enough to start the plane and supply days of power for the G-5. I have not installed the G-3, but I have installed 2 planes with Dual G-5's (AI & HSI). With dual G-5's in a certified plane you are required toÂ
have dual Garmin batteries... That is $300 for a stinking 1 or 2 AH battery. Yea, I would be very happy to install a second battery - a small one - With just enough to start the plane in a 24:00 DARK stranded situation. Â
Yea, happened to me one night. No Fun!

Barry


Was this in spite of a considered preventative
maintenance program? What was the battery's last
cap-check value before the failure?

A battery that is watched and maintained as
carefully as tires, belts, propeller nicks
air cleaners and engine oil is very unlikely
to fail. Dual alternators virtually assures
you of engine driven energy in spite of the
loss of one alternator.

The rule of thumb for battery replacement
in the TC world is when it falls to less than
75% of original capacity . . . in the modern
RG battery world, this means it probably
still cranks the engine but is in substantial
decline on an ever increasing slope to failure
yet unlikely to go belly up away from your
home hangar.

Few light aircraft owner's manuals speak to
affirmative-action maintenance programs . . .
but I'd bet that top-billing in the cast of performers
virtually all dark-n-stormy night stories that
speak to battery failure is a beyond-service-life
battery.

Bob . . .


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mmoyle



Joined: 15 Jun 2015
Posts: 9
Location: Platinum, Alaska

PostPosted: Tue Apr 10, 2018 4:07 pm    Post subject: Please critique my electrical design Reply with quote

Quick load test on a battery is…mags grounded or off and mixture pulled. Crank the engine and monitor the battery voltage. If after 15 seconds the battery voltage does NOT drop below 10.6 volts DC the battery is good. If not charge the battery and test again.
Mark Moyle
Platinum Alaska
From: <owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)> on behalf of Rene <rene(at)felker.com (rene(at)felker.com)>
Reply-To: <aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)>
Date: Tuesday, April 10, 2018 at 3:35 PM
To: <aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)>
Subject: RE: Please critique my electrical design

<![endif]--> <![endif]-->
I do not know about what sells…..but I have mine load tested at Batteries +.

I have two batteries and two alternators. I have one battery that is 10+ years and the other is about 5 now. I had two battery failures….one self induced and the other was infant mortality.

Rene'
801-721-6080

From: owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com) <owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)> On Behalf Of FLYaDIVE
Sent: Tuesday, April 10, 2018 5:15 PM
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Subject: Re: Please critique my electrical design

Bob:



Let's get a show of hands...

How many Pilots out there have a LOAD tester?

I can't get owners to check their tires and you want them to load test a battery!

Granted! This is a aero-electric email list and many are builders. So, if there are fellows out there that do have a load tester I doubt that would cover the rest of the BUYERS that only purchased the plane and did not build.

What do you think would sell a plane faster:

'Oh, and this plane has Dual Alternators and Dual Batteries.'

Or...

'And every year at annual I Load Test the battery."



Barry



On Tue, Apr 10, 2018 at 4:44 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
Quote:

At 03:01 PM 4/10/2018, you wrote:
Quote:

 With two alternators, why a backup battery?
 Bob . . .

​Because what if the battery fails?
G-5's can have the Garmin $150 TINNY battery or ​you can apply that money to a much larger second battery which will be big enough to start the plane and supply days of power for the G-5. I have not installed the G-3, but I have installed 2 planes with Dual G-5's (AI & HSI). With dual G-5's in a certified plane you are required toÂ
have dual Garmin batteries... That is $300 for a stinking 1 or 2 AH battery. Yea, I would be very happy to install a second battery - a small one - With just enough to start the plane in a 24:00 DARK stranded situation. Â
Yea, happened to me one night. No Fun!

Barry


Was this in spite of a considered preventative
maintenance program? What was the battery's last
cap-check value before the failure?

A battery that is watched and maintained as
carefully as tires, belts, propeller nicks
air cleaners and engine oil is very unlikely
to fail. Dual alternators virtually assures
you of engine driven energy in spite of the
loss of one alternator.

The rule of thumb for battery replacement
in the TC world is when it falls to less than
75% of original capacity . . . in the modern
RG battery world, this means it probably
still cranks the engine but is in substantial
decline on an ever increasing slope to failure
yet unlikely to go belly up away from your
home hangar.

Few light aircraft owner's manuals speak to
affirmative-action maintenance programs . . .
but I'd bet that top-billing in the cast of performers
virtually all dark-n-stormy night stories that
speak to battery failure is a beyond-service-life
battery.

Bob . . .


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cluros(at)gmail.com
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PostPosted: Tue Apr 10, 2018 4:19 pm    Post subject: Please critique my electrical design Reply with quote

I have a load tester. I leave it in the hanger though as superfluous weight (like for example 4 electrical sources) is a performance killer.

On Tue, Apr 10, 2018, 7:19 PM FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)> wrote:

Quote:
Bob:
Let's get a show of hands...
How many Pilots out there have a LOAD tester?
I can't get owners to check their tires and you want them to load test a battery!
Granted!  This is a aero-electric email list and many are builders.  So, if there are fellows out there that do have a load tester I doubt that would cover the rest of the BUYERS that only purchased the plane and did not build.
What do you think would sell a plane faster:
'Oh, and this plane has Dual Alternators and Dual Batteries.'
Or..
'And every year at annual I Load Test the battery."
Barry


On Tue, Apr 10, 2018 at 4:44 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
Quote:
At 03:01 PM 4/10/2018, you wrote:

Quote:
 With two alternators, why a backup battery?


  Bob . . .


​Because what if the battery fails?
G-5's can have the Garmin $150 TINNY battery or ​you can apply that money to a much larger second battery which will be big enough to start the plane and supply days of power for the G-5.  I have not installed the G-3,  but I have installed 2 planes with Dual G-5's (AI & HSI).  With dual G-5's in a certified plane you are required toÂ
have dual Garmin batteries...  That is $300 for a stinking 1 or 2 AH battery.  Yea, I would be very happy to install a second battery - a small one - With just enough to start the plane in a 24:00 DARK stranded situation. Â
Yea, happened to me one night.  No Fun!

Barry

  Was this in spite of a considered preventative
  maintenance program? What was the battery's last
  cap-check value before the failure?

  A battery that is watched and maintained as
  carefully as tires, belts, propeller nicks
  air cleaners and engine oil is very unlikely
  to fail. Dual alternators virtually assures
  you of engine driven energy in spite of the
  loss of one alternator.

  The rule of thumb for battery replacement
  in the TC world is when it falls to less than
  75% of original capacity . . . in the modern
  RG battery world, this means it probably
  still cranks the engine but is in substantial
  decline on an ever increasing slope to failure
  yet unlikely to go belly up away from your
  home hangar.

  Few light aircraft owner's manuals speak to
  affirmative-action maintenance programs . . .
  but I'd bet that top-billing in the cast of performers
  virtually all dark-n-stormy night stories that
  speak to battery failure is a beyond-service-life
  battery.
 



  Bob . . .



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N884RA



Joined: 22 Mar 2018
Posts: 6

PostPosted: Tue Apr 10, 2018 4:55 pm    Post subject: Re: Please critique my electrical design Reply with quote

Thanks for the feedback!

user9253 wrote:
The main voltage regulator sense terminal (3?) should
connect to the to the main power bus and not share a wire
with the field current. The way it is connected now will
eventually lead to overvoltage conditions due to
increasing resistance as terminals and switch contacts
corrode over time.


I just followed Bob's wiring on the Z-13/8, but I'll be sure to check that against the manufacture's instructions when I buy the voltage regulator.

Quote:
The start switch does not need to be on a circuit
breaker. A fuse on the main power bus should never blow.
And if it did, there should be a good reason.
And the plane will be safely on the ground if and
when the start fuse does blow.


I put the starter on a CB so I'd have an alternate way of turning it off in the event the starter switch failed closed. I suppose turning off the master would have the same effect though.

Quote:
There should not be 2 fuselinks in series going to the
main alternator field breaker. One is good enough. The
second one is redundant.


The distance between Main Bus 1 and Main Bus 2 was 6 feet, so I thought I needed circuit protection on it. Other builders advised me not to use a fuse for fear of nuisance trips. I've since moved the location of the CBs to the front of the instrument panel which has reduced the length of that wire run to less than 18". Does that length of wire need circuit protection?

Quote:
Who knows if the aux alt 2 amp breaker will trip before
the 15 amps fuse blows. Maybe increase the fuse to 30
amps?


I have to confess I'm don't understand the intricacies of that set up as well as I wish. Bob also recommends 30A inline fuse and I'm not completely sure why I have it shown as 15A. The manufacturer recommends a 10A CB as the feed into the main bus, but I opted to go with Bob's design. Or I attempted to! Confused

Quote:
Consider doing away with the avionics switch.


I know I'm in the old school here, but I want the switch function.

Quote:
Maybe the trim indicator and fuel gauge should be on the
endurance bus. They use very little power.


That's a good point.

Thanks again,
Rob


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PostPosted: Tue Apr 10, 2018 6:40 pm    Post subject: Please critique my electrical design Reply with quote

Since it only takes around 5% of capacity to start the engine, that might not be the most reliable test.

On 4/10/2018 7:06 PM, Mark Moyle wrote:

Quote:
Quick load test on a battery is…mags grounded or off and mixture pulled.  Crank the engine and monitor the battery voltage.  If after 15 seconds the battery voltage does NOT drop below 10.6 volts DC the battery is good.  If not charge the battery and test again.
Mark Moyle
Platinum Alaska 


From: <owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)> on behalf of Rene <rene(at)felker.com (rene(at)felker.com)>
Reply-To: <aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)>
Date: Tuesday, April 10, 2018 at 3:35 PM
To: <aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)>
Subject: RE: Please critique my electrical design



<![endif]--> <![endif]-->
I do not know about what sells…..but I have mine load tested at Batteries +.
 
I have two batteries and two alternators.  I have one battery that is 10+ years and the other is about 5 now.  I had two battery failures….one self induced and the other was infant mortality.
 
Rene'
801-721-6080
 
From: owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com) <owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)> On Behalf Of FLYaDIVE
Sent: Tuesday, April 10, 2018 5:15 PM
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Subject: Re: Please critique my electrical design
 
Bob:

 

Let's get a show of hands...

How many Pilots out there have a LOAD tester?

I can't get owners to check their tires and you want them to load test a battery!

Granted!  This is a aero-electric email list and many are builders.  So, if there are fellows out there that do have a load tester I doubt that would cover the rest of the BUYERS that only purchased the plane and did not build.

What do you think would sell a plane faster:

'Oh, and this plane has Dual Alternators and Dual Batteries.'

Or...

'And every year at annual I Load Test the battery."

 

Barry

 


 
On Tue, Apr 10, 2018 at 4:44 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
Quote:

At 03:01 PM 4/10/2018, you wrote:


Quote:

 With two alternators, why a backup battery?


  Bob . . .

​Because what if the battery fails?
G-5's can have the Garmin $150 TINNY battery or ​you can apply that money to a much larger second battery which will be big enough to start the plane and supply days of power for the G-5.  I have not installed the G-3,  but I have installed 2 planes with Dual G-5's (AI & HSI).  With dual G-5's in a certified plane you are required toÂ
have dual Garmin batteries...  That is $300 for a stinking 1 or 2 AH battery.  Yea, I would be very happy to install a second battery - a small one - With just enough to start the plane in a 24:00 DARK stranded situation. Â
Yea, happened to me one night.  No Fun!

Barry


  Was this in spite of a considered preventative
  maintenance program? What was the battery's last
  cap-check value before the failure?

  A battery that is watched and maintained as
  carefully as tires, belts, propeller nicks
  air cleaners and engine oil is very unlikely
  to fail. Dual alternators virtually assures
  you of engine driven energy in spite of the
  loss of one alternator.

  The rule of thumb for battery replacement
  in the TC world is when it falls to less than
  75% of original capacity . . . in the modern
  RG battery world, this means it probably
  still cranks the engine but is in substantial
  decline on an ever increasing slope to failure
  yet unlikely to go belly up away from your
  home hangar.

  Few light aircraft owner's manuals speak to
  affirmative-action maintenance programs . . .
  but I'd bet that top-billing in the cast of performers
  virtually all dark-n-stormy night stories that
  speak to battery failure is a beyond-service-life
  battery.
 


  Bob . . .


 




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kenryan



Joined: 20 Oct 2009
Posts: 258

PostPosted: Tue Apr 10, 2018 7:07 pm    Post subject: Please critique my electrical design Reply with quote

Charlie, It would seem to me that putting a consistent load (turning the
starter, similar temperatures) on the battery, and noting the voltage drop
would constitute a valid test. It is surely not the most accurate, but if
done in a consistent manner, it is seems it would be much better than doing
nothing at all. Also, I don't see how the fact that it only takes 5% of
battery capacity to start the engine has any relevance on whether such a
rudimentary engine spinning stress test is valid, or not. Are you saying
that it is likely that one would note the same voltage drop on a brand new
battery as on a battery that is nearing the end of its useful life?
Enlighten!

On Tue, Apr 10, 2018 at 6:39 PM, Charlie England <ceengland7(at)gmail.com>
wrote:

[quote] Since it only takes around 5% of capacity to start the engine, that might
not be the most reliable test.

On 4/10/2018 7:06 PM, Mark Moyle wrote:

Quick load test on a battery is…mags grounded or off and mixture pulled.
Crank the engine and monitor the battery voltage. If after 15 seconds the
battery voltage does NOT drop below 10.6 volts DC the battery is good. If
not charge the battery and test again.
Mark Moyle
Platinum Alaska

From: <owner-aeroelectric-list-server(at)matronics.com> on behalf of Rene <
rene(at)felker.com>
Reply-To: <aeroelectric-list(at)matronics.com>
Date: Tuesday, April 10, 2018 at 3:35 PM
To: <aeroelectric-list(at)matronics.com>
Subject: RE: Please critique my electrical design

I do not know about what sells…..but I have mine load tested at Batteries
+.

I have two batteries and two alternators. I have one battery that is 10+
years and the other is about 5 now. I had two battery failures….one self
induced and the other was infant mortality.

Rene'

801-721-6080

*From:* owner-aeroelectric-list-server(at)matronics.com <
owner-aeroelectric-list-server(at)matronics.com> *On Behalf Of *FLYaDIVE
*Sent:* Tuesday, April 10, 2018 5:15 PM
*To:* aeroelectric-list(at)matronics.com
*Subject:* Re: Please critique my electrical design

Bob:

Let's get a show of hands...

How many Pilots out there have a LOAD tester?

I can't get owners to check their tires and you want them to load test a
battery!

Granted! This is a aero-electric email list and many are builders. So,
if there are fellows out there that do have a load tester I doubt that
would cover the rest of the BUYERS that only purchased the plane and did
not build.

What do you think would sell a plane faster:

'Oh, and this plane has Dual Alternators and Dual Batteries.'

Or...

'And every year at annual I Load Test the battery."

Barry

On Tue, Apr 10, 2018 at 4:44 PM, Robert L. Nuckolls, III <
nuckolls.bob(at)aeroelectric.com> wrote:

At 03:01 PM 4/10/2018, you wrote:
 With two alternators, why a backup battery?

 Bob . . .
​Because what if the battery fails?
G-5's can have the Garmin $150 TINNY battery or ​you can apply that
money to a much larger second battery which will be big enough to start the
plane and supply days of power for the G-5. I have not installed the
G-3, but I have installed 2 planes with Dual G-5's (AI & HSI). With
dual G-5's in a certified plane you are required toÂ
have dual Garmin batteries... That is $300 for a stinking 1 or 2 AH
battery. Yea, I would be very happy to install a second battery - a small
one - With just enough to start the plane in a 24:00 DARK stranded
situation. Â
Yea, happened to me one night. No Fun!

Barry
Was this in spite of a considered preventative
maintenance program? What was the battery's last
cap-check value before the failure?

A battery that is watched and maintained as
carefully as tires, belts, propeller nicks
air cleaners and engine oil is very unlikely
to fail. Dual alternators virtually assures
you of engine driven energy in spite of the
loss of one alternator.

The rule of thumb for battery replacement
in the TC world is when it falls to less than
75% of original capacity . . . in the modern
RG battery world, this means it probably
still cranks the engine but is in substantial
decline on an ever increasing slope to failure
yet unlikely to go belly up away from your
home hangar.

Few light aircraft owner's manuals speak to
affirmative-action maintenance programs . . .
but I'd bet that top-billing in the cast of performers
virtually all dark-n-stormy night stories that
speak to battery failure is a beyond-service-life
battery.
Bob . . .
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user9253



Joined: 28 Mar 2008
Posts: 1163
Location: Riley TWP Michigan

PostPosted: Tue Apr 10, 2018 7:10 pm    Post subject: Re: Please critique my electrical design Reply with quote

If you look at B&C's wiring diagram
https://www.bandc.aero/pdfs/LR3C_Installation_Manual.pdf
the voltage sense terminal 3 is separate from the field terminal 6.
Also look at Bob's Z-12.
_
One fuselink provides protection for everything downstream of it.
A second fuselink is not required. All the second one does is make
an unnecessary failure point.
_
The maximum of 6" rule of thumb for unprotected wires is not cast
in stone. It all depends on what dangers the wire is exposed to.
_
Circuit breakers are mechanical devices that take time to operate.
That time could be longer than it takes a smaller fuse to blow. A larger
fuse will be slower to blow in case of the over-voltage module shorting out.
The aux alternator fuse protects the battery. It will not hurt to use a 30
amp fuse. Z-13/8 uses a 20awg fuselink which will probably carry more
than 30 amps before the wire melts. The aux alternator output is self
current limiting and will never exceed 10 amps or so.


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PostPosted: Tue Apr 10, 2018 8:00 pm    Post subject: Please critique my electrical design Reply with quote

If the only use for the battery is starting, then it's a valid test. But if the battery is backup electrical power for the alternator and you need electrical power to keep the flight safe to its conclusion, then it isn't a valid test.

It can be down to 50% capacity & still reliably crank the engine. But if the alternator dies and you need the battery to keep the engine running (electronic ignition, glass panel in IFR, etc), then you'd only have half or less the time you thought you'd have, based on the battery's rated capacity.

It's the difference between power and energy. 400 HP Corvette with 1/2 gallon of gas, vs 80 HP Chevette with 15 gallons.

That help?

On 4/10/2018 10:06 PM, Ken Ryan wrote:

Quote:
Charlie, It would seem to me that putting a consistent load (turning the starter, similar temperatures) on the battery, and noting the voltage drop would constitute a valid test. It is surely not the most accurate, but if done in a consistent manner, it is seems it would be much better than doing nothing at all. Also, I don't see how the fact that it only takes 5% of battery capacity to start the engine has any relevance on whether such a rudimentary engine spinning stress test is valid, or not. Are you saying that it is likely that one would note the same voltage drop on a brand new battery as on a battery that is nearing the end of its useful life? Enlighten!

On Tue, Apr 10, 2018 at 6:39 PM, Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)> wrote:
Quote:
Since it only takes around 5% of capacity to start the engine, that might not be the most reliable test.

On 4/10/2018 7:06 PM, Mark Moyle wrote:

Quote:
Quick load test on a battery is…mags grounded or off and mixture pulled.  Crank the engine and monitor the battery voltage.  If after 15 seconds the battery voltage does NOT drop below 10.6 volts DC the battery is good.  If not charge the battery and test again.
Mark Moyle
Platinum Alaska 


From: <owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)> on behalf of Rene <rene(at)felker.com (rene(at)felker.com)>
Reply-To: <aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)>
Date: Tuesday, April 10, 2018 at 3:35 PM
To: <aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)>
Subject: RE: Please critique my electrical design




I do not know about what sells…..but I have mine load tested at Batteries +.
 
I have two batteries and two alternators.  I have one battery that is 10+ years and the other is about 5 now.  I had two battery failures….one self induced and the other was infant mortality.
 
Rene'
801-721-6080
 
From: owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com) <owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)> On Behalf Of FLYaDIVE
Sent: Tuesday, April 10, 2018 5:15 PM
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Subject: Re: Please critique my electrical design
 
Bob:

 

Let's get a show of hands...

How many Pilots out there have a LOAD tester?

I can't get owners to check their tires and you want them to load test a battery!

Granted!  This is a aero-electric email list and many are builders.  So, if there are fellows out there that do have a load tester I doubt that would cover the rest of the BUYERS that only purchased the plane and did not build.

What do you think would sell a plane faster:

'Oh, and this plane has Dual Alternators and Dual Batteries.'

Or...

'And every year at annual I Load Test the battery."

 

Barry

 


 
On Tue, Apr 10, 2018 at 4:44 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
Quote:

At 03:01 PM 4/10/2018, you wrote:


Quote:

 With two alternators, why a backup battery?


  Bob . . .

​Because what if the battery fails?
G-5's can have the Garmin $150 TINNY battery or ​you can apply that money to a much larger second battery which will be big enough to start the plane and supply days of power for the G-5.  I have not installed the G-3,  but I have installed 2 planes with Dual G-5's (AI & HSI).  With dual G-5's in a certified plane you are required toÂ
have dual Garmin batteries...  That is $300 for a stinking 1 or 2 AH battery.  Yea, I would be very happy to install a second battery - a small one - With just enough to start the plane in a 24:00 DARK stranded situation. Â
Yea, happened to me one night.  No Fun!

Barry


  Was this in spite of a considered preventative
  maintenance program? What was the battery's last
  cap-check value before the failure?

  A battery that is watched and maintained as
  carefully as tires, belts, propeller nicks
  air cleaners and engine oil is very unlikely
  to fail. Dual alternators virtually assures
  you of engine driven energy in spite of the
  loss of one alternator.

  The rule of thumb for battery replacement
  in the TC world is when it falls to less than
  75% of original capacity . . . in the modern
  RG battery world, this means it probably
  still cranks the engine but is in substantial
  decline on an ever increasing slope to failure
  yet unlikely to go belly up away from your
  home hangar.

  Few light aircraft owner's manuals speak to
  affirmative-action maintenance programs . . .
  but I'd bet that top-billing in the cast of performers
  virtually all dark-n-stormy night stories that
  speak to battery failure is a beyond-service-life
  battery.
 


  Bob . . .


 





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donvansanten(at)gmail.com
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PostPosted: Tue Apr 10, 2018 8:07 pm    Post subject: Please critique my electrical design Reply with quote

A valid test needs to take the battery to lower than 75%. After that fully charge and then retest, I usually go the manufactures suggested low charge level. This will tell you if the bat is capable of 75% charge.If not, replace it.
I do this and also replace my AGM Bat
every two years. I have no steam gagues in my AC.

On Tuesday, April 10, 2018, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
[quote] Charlie, It would seem to me that putting a consistent load (turning the starter, similar temperatures) on the battery, and noting the voltage drop would constitute a valid test. It is surely not the most accurate, but if done in a consistent manner, it is seems it would be much better than doing nothing at all. Also, I don't see how the fact that it only takes 5% of battery capacity to start the engine has any relevance on whether such a rudimentary engine spinning stress test is valid, or not. Are you saying that it is likely that one would note the same voltage drop on a brand new battery as on a battery that is nearing the end of its useful life? Enlighten!
On Tue, Apr 10, 2018 at 6:39 PM, Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)> wrote:
>
> Since it only takes around 5% of capacity to start the engine, that might not be the most reliable test.
>
> On 4/10/2018 7:06 PM, Mark Moyle wrote:
>
> Quick load test on a battery is…mags grounded or off and mixture pulled.  Crank the engine and monitor the battery voltage.  If after 15 seconds the battery voltage does NOT drop below 10.6 volts DC the battery is good.  If not charge the battery and test again.
> Mark Moyle
> Platinum Alaska 
> From: <owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)> on behalf of Rene <rene(at)felker.com (rene(at)felker.com)>
> Reply-To: <aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)>
> Date: Tuesday, April 10, 2018 at 3:35 PM
> To: <aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)>
> Subject: RE: Please critique my electrical design
>
> I do not know about what sells…..but I have mine load tested at Batteries +.
>
>  
>
> I have two batteries and two alternators.  I have one battery that is 10+ years and the other is about 5 now.  I had two battery failures….one self induced and the other was infant mortality.
>
>  
>
> Rene'
>
> 801-721-6080
>
>  
>
> From: owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com) <owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)> On Behalf Of FLYaDIVE
> Sent: Tuesday, April 10, 2018 5:15 PM
> To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
> Subject: Re: Please critique my electrical design
>
>  
>
> Bob:
>
>  
>
> Let's get a show of hands...
>
> How many Pilots out there have a LOAD tester?
>
> I can't get owners to check their tires and you want them to load test a battery!
>
> Granted!  This is a aero-electric email list and many are builders.  So, if there are fellows out there that do have a load tester I doubt that would cover the rest of the BUYERS that only purchased the plane and did not build.
>
> What do you think would sell a plane faster:
>
> 'Oh, and this plane has Dual Alternators and Dual Batteries.'
>
> Or...
>
> 'And every year at annual I Load Test the battery."
>
>  
>
> Barry
>
>  
>
>  
>
> On Tue, Apr 10, 2018 at 4:44 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
>
> At 03:01 PM 4/10/2018, you wrote:
> Â With two alternators, why a backup battery?
>
>   Bob . . .
>
> ​Because what if the battery fails?
> G-5's can have the Garmin $150 TINNY battery or ​you can apply that money to a much larger second battery which will be big enough to start the plane and supply days of power for the G-5.  I have not installed the G-3,  but I have installed 2 planes with Dual G-5's (AI & HSI).  With dual G-5's in a certified plane you are required toÂ
> have dual Garmin batteries...  That is $300 for a stinking 1 or 2 AH battery.  Yea, I would be very happy to install a second battery - a small one - With just enough to start the plane in a 24:00 DARK stranded situation. Â
> Yea, happened to me one night.  No Fun!
>
> Barry
>
>   Was this in spite of a considered preventative
>   maintenance program? What was the battery's last
>   cap-check value before the failure?
>
>   A battery that is watched and maintained as
>   carefully as tires, belts, propeller nicks
>   air cleaners and engine oil is very unlikely
>   to fail. Dual alternators virtually assures
>   you of engine driven energy in spite of the
>   loss of one alternator.
>
>   The rule of thumb for battery replacement
>   in the TC world is when it falls to less than
>   75% of original capacity . . . in the modern
>   RG battery world, this means it probably
>   still cranks the engine but is in substantial
>   decline on an ever increasing slope to failure
>   yet unlikely to go belly up away from your
>   home hangar.
>
>   Few light aircraft owner's manuals speak to
>   affirmative-action maintenance programs . . .
>   but I'd bet that top-billing in the cast of performers
>   virtually all dark-n-stormy night stories that
>   speak to battery failure is a beyond-service-life
>   battery.
>  
>
>   Bob . . .
>
>  
>
> <https://ci5.googleusercontent.com/proxy/M2-ctzJ6_LQ91UgZhwqiad0T5NTuMKxW_Wyq6Hwe3O5NlmAAXUIN70IL704-sgeGK_EUk1emkSHFb89ojOgJMH73hkYFO_E705cCwjimC_9onvxtCWJ7EZN27-OVK4jjjO_ucLFuIks7qIMzuswpUsWNzJ_u=s0-d-e1-ft#https://ipmcdn.avast.com/images/icons/icon-envelope-tick-round-orange-animated-no-repeat-v1.gif> Virus-free. www.avast.com


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kenryan



Joined: 20 Oct 2009
Posts: 258

PostPosted: Tue Apr 10, 2018 8:26 pm    Post subject: Please critique my electrical design Reply with quote

Charlie, It seems to me that your response does not address that the test
involves monitoring the voltage drop that occurs when the consistent load
is applied. The test is not simply, "will the battery spin the prop." The
test is, "what is the voltage drop caused by spinning the prop."

It seems to me that if the voltage drops down further on a worn out battery
than it does on a fresh battery, there is at least the possibility that
this test could be quite useful. It does not seem to me that the simple
fact the battery "can be down 50% capacity and still reliably crank the
engine" is germane to whether or not monitoring voltage under a consistent
load (in this case spinning the propeller for a specific time) can be
useful as a way to determine whether or not it is time to replace a battery


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N884RA



Joined: 22 Mar 2018
Posts: 6

PostPosted: Wed Apr 11, 2018 3:37 am    Post subject: Re: Please critique my electrical design Reply with quote

Joe,

Thanks again for you help!

user9253 wrote:
If you look at B&C's wiring diagram
https://www.bandc.aero/pdfs/LR3C_Installation_Manual.pdf
the voltage sense terminal 3 is separate from the field terminal 6.
Also look at Bob's Z-12.


I followed B&C's parts list, but when they switched it from a generic Ford regulator to the LR3C I didn't realize I should have used the Z-12 architecture for that component. Z-12 doesn't include a fuseable link or crowbar -- should I take those out? I put the LV Warn light back in my design for now like the Z-12 has, but I'm sure the G3X has an input for that, so a stand-alone light won't be required. I'll also have to figure out if I still need the Lo Volt Warn CB in that arrangement.

Quote:
One fuselink provides protection for everything downstream of it.
A second fuselink is not required. All the second one does is make
an unnecessary failure point.


That makes sense now, thanks!

Quote:
The maximum of 6" rule of thumb for unprotected wires is not cast
in stone. It all depends on what dangers the wire is exposed to.


I updated my design this morning, and removed the second fuseable link.

Quote:
Circuit breakers are mechanical devices that take time to operate.
That time could be longer than it takes a smaller fuse to blow. A larger
fuse will be slower to blow in case of the over-voltage module shorting out.
The aux alternator fuse protects the battery. It will not hurt to use a 30
amp fuse. Z-13/8 uses a 20awg fuselink which will probably carry more
than 30 amps before the wire melts. The aux alternator output is self
current limiting and will never exceed 10 amps or so.


I think Bob replaced the Z-13's fusable link with a 30A inline fuse on the latest version. I'm having trouble finding a suitable component for that. I know Bonanzas have several glass fuses mounted on the firewall just above the battery (near their current limiters) and I suppose I could do something similar if required.

Does anyone have a part number/vendor they could recommend for a 30A inline fuse?


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PostPosted: Wed Apr 11, 2018 4:42 am    Post subject: Please critique my electrical design Reply with quote

Well, the 1st issue is establishing what Mark meant when he mentioned that 10.6V limit. Because unless he's using a truly massively oversized battery, it will *always* drop below 10.6V during cranking. That's why old Kettering ignition (points & condenser) cars had ballast resistors in series with their points. The points actually run on around 6-8 volts, and resistor gets switched out of the circuit during cranking because of the battery voltage drop due to cranking loads. Dropping down around 10V (sometimes even lower) is fairly common during starting. Look back through the archives for all the complaints about EFISs rebooting while cranking the engine. 

So....I'm betting that Mark meant he's measuring 10.6V *after* 15 seconds of cranking, but with no/minimal load on the battery. Now, go back to the Corvette/Chevette example. If you accelerate the Corvette for 15 seconds, it'll still have 400 HP, but you may only have 3 seconds of capacity (gas) left. 
Mark's test is even less valid if one has chosen a Lithium chemistry battery; their voltage has much less decline until it 'falls off the cliff' at full discharge.
The real test is monitoring *how long* voltage remains above the voltage that indicates complete discharge (which is around 10.5 V), while the typical load from the plane's required (endurance bus) electronics is applied.

On Tue, Apr 10, 2018 at 11:24 PM, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
Quote:
Charlie, It seems to me that your response does not address that the test involves monitoring the voltage drop that occurs when the consistent load is applied. The test is not simply, "will the battery spin the prop." The test is, "what is the voltage drop caused by spinning the prop." 
It seems to me that if the voltage drops down further on a worn out battery than it does on a fresh battery, there is at least the possibility that this test could be quite useful. It does not seem to me that the simple fact the battery "can be down 50% capacity and still reliably crank the engine" is germane to whether or not monitoring voltage under a consistent load (in this case spinning the propeller for a specific time) can be useful as a way to determine whether or not it is time to replace a battery.
I'm not saying that the spin-the-prop-and-monitor-voltage test is valid. But it seems to me like it might be.  I just can't see where simply noting that a depleted battery can still spin a prop says anything about the usefulness of such a test. Sorry, but I just can't seem to make that connection. Probably I am a little bit dense Smile -- it wouldn't be the first time.
In evaluating the suggested test, as a starting point I would like to know if the voltage drop would be significantly different on a new vs a worn out battery. If the answer is no, the drop would be about the same, then case closed. Test invalid. But if it turns out the voltage drop is significantly greater on a worn out battery, then I think there is reason to believe that the test might be useful.

On Tue, Apr 10, 2018, 20:04 Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)> wrote:

Quote:
If the only use for the battery is starting, then it's a valid test. But if the battery is backup electrical power for the alternator and you need electrical power to keep the flight safe to its conclusion, then it isn't a valid test.

It can be down to 50% capacity & still reliably crank the engine. But if the alternator dies and you need the battery to keep the engine running (electronic ignition, glass panel in IFR, etc), then you'd only have half or less the time you thought you'd have, based on the battery's rated capacity.

It's the difference between power and energy. 400 HP Corvette with 1/2 gallon of gas, vs 80 HP Chevette with 15 gallons.

That help?

On 4/10/2018 10:06 PM, Ken Ryan wrote:

Quote:
Charlie, It would seem to me that putting a consistent load (turning the starter, similar temperatures) on the battery, and noting the voltage drop would constitute a valid test. It is surely not the most accurate, but if done in a consistent manner, it is seems it would be much better than doing nothing at all. Also, I don't see how the fact that it only takes 5% of battery capacity to start the engine has any relevance on whether such a rudimentary engine spinning stress test is valid, or not. Are you saying that it is likely that one would note the same voltage drop on a brand new battery as on a battery that is nearing the end of its useful life? Enlighten!

On Tue, Apr 10, 2018 at 6:39 PM, Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)> wrote:
Quote:
Since it only takes around 5% of capacity to start the engine, that might not be the most reliable test.

On 4/10/2018 7:06 PM, Mark Moyle wrote:

Quote:
Quick load test on a battery is…mags grounded or off and mixture pulled.  Crank the engine and monitor the battery voltage.  If after 15 seconds the battery voltage does NOT drop below 10.6 volts DC the battery is good.  If not charge the battery and test again.
Mark Moyle
Platinum Alaska 


From: <owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)> on behalf of Rene <rene(at)felker.com (rene(at)felker.com)>
Reply-To: <aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)>
Date: Tuesday, April 10, 2018 at 3:35 PM
To: <aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)>
Subject: RE: Please critique my electrical design




I do not know about what sells…..but I have mine load tested at Batteries +.
 
I have two batteries and two alternators.  I have one battery that is 10+ years and the other is about 5 now.  I had two battery failures….one self induced and the other was infant mortality.
 
Rene'
801-721-6080
 
From: owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com) <owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)> On Behalf Of FLYaDIVE
Sent: Tuesday, April 10, 2018 5:15 PM
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Subject: Re: Please critique my electrical design
 
Bob:

 

Let's get a show of hands...

How many Pilots out there have a LOAD tester?

I can't get owners to check their tires and you want them to load test a battery!

Granted!  This is a aero-electric email list and many are builders.  So, if there are fellows out there that do have a load tester I doubt that would cover the rest of the BUYERS that only purchased the plane and did not build.

What do you think would sell a plane faster:

'Oh, and this plane has Dual Alternators and Dual Batteries.'

Or...

'And every year at annual I Load Test the battery."

 

Barry

 


 
On Tue, Apr 10, 2018 at 4:44 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
Quote:

At 03:01 PM 4/10/2018, you wrote:


Quote:

 With two alternators, why a backup battery?


  Bob . . .

​Because what if the battery fails?
G-5's can have the Garmin $150 TINNY battery or ​you can apply that money to a much larger second battery which will be big enough to start the plane and supply days of power for the G-5.  I have not installed the G-3,  but I have installed 2 planes with Dual G-5's (AI & HSI).  With dual G-5's in a certified plane you are required toÂ
have dual Garmin batteries...  That is $300 for a stinking 1 or 2 AH battery.  Yea, I would be very happy to install a second battery - a small one - With just enough to start the plane in a 24:00 DARK stranded situation. Â
Yea, happened to me one night.  No Fun!

Barry


  Was this in spite of a considered preventative
  maintenance program? What was the battery's last
  cap-check value before the failure?

  A battery that is watched and maintained as
  carefully as tires, belts, propeller nicks
  air cleaners and engine oil is very unlikely
  to fail. Dual alternators virtually assures
  you of engine driven energy in spite of the
  loss of one alternator.

  The rule of thumb for battery replacement
  in the TC world is when it falls to less than
  75% of original capacity . . . in the modern
  RG battery world, this means it probably
  still cranks the engine but is in substantial
  decline on an ever increasing slope to failure
  yet unlikely to go belly up away from your
  home hangar.

  Few light aircraft owner's manuals speak to
  affirmative-action maintenance programs . . .
  but I'd bet that top-billing in the cast of performers
  virtually all dark-n-stormy night stories that
  speak to battery failure is a beyond-service-life
  battery.
 


  Bob . . .


 





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