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supik

Joined: 22 Aug 2018
Posts: 70

Posted: Sun Jan 13, 2019 3:29 am Post subject: Basic Elec. Diagram -critique pls

(I have posted this on VAF as well)



This is my preliminary diagram for my RV-10



Single battery, dual alternator setup. (60amp B&C + 30amp B&C)

Backup & Master switches ON during normal ops.



Both alternators will be ON during normal ops.

ALT-1 (60amp) regulator preset at 14.4V

ALT-2 (30amp) regulator preset at 13.8V



Both regulators are LR3C-14

LV lights from regulators NOT utilized. Respective BUS voltages monitored by G3X Touch. 

-MAIN BUS threshold monitoring at or below 13.8V triggers (MASTER CAUT) MAIN BUS LV

-ESS BUS threshold monitoring at or below 13.0V triggers (MASTER WARN) ESS BUS LV

I hope this is possible to setup with the G3X Touch, expert opinion is welcomed.



Shall the ESS-BUS relay fail, ESS-BUS alternate feed is provided by a diode.



EDIT: New version uploaded with updated E BUS AWG

EDIT: Updated Load Analysis attached

EDIT: Updated Diagram v.010 with continuos duty type contactor for E BUS

OM-ELA Basic Elec Diagram v.010 E BUS Relay replaced.jpg

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_________________
Igor

RV10 in progress

Last edited by supik on Mon Jan 14, 2019 7:51 am; edited 4 times in total

art(at)zemon.name
Guest

Posted: Sun Jan 13, 2019 4:17 am Post subject: Basic Elec. Diagram -critique pls

Igor,

What are you going to connect to your essential bus? Do you need it at all? I started with a wiring scheme like you have and eliminated the ebus when I realized that, in case of a primary alternator failure, I could simply turn off the pitot heat and landing lights. That reduces the current draw below 30A.

    -- Art Z.





On Sun, Jan 13, 2019 at 5:45 AM supik <bionicad(at)hotmail.com (bionicad(at)hotmail.com)> wrote:



 	  Quote: 	
		  --> AeroElectric-List message posted by: "supik" <bionicad(at)hotmail.com (bionicad(at)hotmail.com)>

 

 (I have posted this on VAF as well)

 

 This is my preliminary diagram for my RV-10

 

 Single battery, dual alternator setup. (60amp B&C + 30amp B&C)

 Backup & Master switches ON during normal ops.

 

 Both alternators will be ON during normal ops.

 ALT-1 (60amp) regulator preset at 14.4V

 ALT-2 (30amp) regulator preset at 13.8V

 

 Both regulators are L3C-14

 LV lights from regulators NOT utilized. Respective BUS voltages monitored by G3X Touch. 

 -MAIN BUS threshold monitoring at or below 13.8V triggers (MASTER CAUT) MAIN BUS LV

 -ESS BUS threshold monitoring at or below 13.0V triggers (MASTER WARN) ESS BUS LV

 I hope this is possible to setup with the G3X Touch, expert opinion is welcomed.

 

 Shall the ESS-BUS relay fail, ESS-BUS alternate feed is provided by a diode. 	


-- 

https://CheerfulCurmudgeon.com/"Be kind, for everyone you meet is fighting a hard battle."

Kellym

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

Posted: Sun Jan 13, 2019 6:39 am Post subject: Basic Elec. Diagram -critique pls

Hard to judge without knowing anything about the electrical load besides 

you plan one electronic ignition. What do you expect normal cruise VFR 

load to be, normal IFR/IMC load, what you would shed if primary 

alternator failed. Is your normal mission pleasure VFR without "need" to 

keep a business schedule? Or you plan on business use that requires 

keeping a tighter schedule, flying as much IFR as needed, within 

airframe/equipment limits? Are you going with mechanical fuel injection 

or electronic fuel injection with required high pressure electric pump?

What type of lighting with what current draw?

I would defer deciding on brand and model of EFIS until you are ready to 

build the panel...new options come along every month. You likely will be 

modifying your electrical diagram up to that point as well. The items 

needed for install in the wing and fuselage are well defined. You will 

need a master solenoid at the battery in the rear compartment, nav and 

strobe lights and some form of landing light. All those can be wired 

generically until you are really ready to do the instrument 

panel/firewall wiring.



On 1/13/2019 4:29 AM, supik wrote:

 	  Quote: 	
		   

 

 (I have posted this on VAF as well)

 

 This is my preliminary diagram for my RV-10

 

 Single battery, dual alternator setup. (60amp B&C + 30amp B&C)

 Backup & Master switches ON during normal ops.

 

 Both alternators will be ON during normal ops.

 ALT-1 (60amp) regulator preset at 14.4V

 ALT-2 (30amp) regulator preset at 13.8V

 

 Both regulators are L3C-14

 LV lights from regulators NOT utilized. Respective BUS voltages monitored by G3X Touch.

 -MAIN BUS threshold monitoring at or below 13.8V triggers (MASTER CAUT) MAIN BUS LV

 -ESS BUS threshold monitoring at or below 13.0V triggers (MASTER WARN) ESS BUS LV

 I hope this is possible to setup with the G3X Touch, expert opinion is welcomed.

 

 Shall the ESS-BUS relay fail, ESS-BUS alternate feed is provided by a diode.

 

 --------

 Igor

 

 RV10 in progress

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=486919#486919

 

 

 

 

 Attachments:

 

 http://forums.matronics.com//files/om_ela_basic_elec_diagram_v005_minor_txt_changes_144.jpg

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

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Jan 13, 2019 10:56 am Post subject: Basic Elec. Diagram -critique pls

At 05:29 AM 1/13/2019, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "supik" <bionicad(at)hotmail.com>



 (I have posted this on VAF as well)



 This is my preliminary diagram for my RV-10



 Single battery, dual alternator setup. (60amp B&C + 30amp B&C)

 Backup & Master switches ON during normal ops.



 Both alternators will be ON during normal ops. 	


   E-bus alternate feed on or off?  Why

   run both alternators?



   Driving the e-bus with an alternator

   makes the alternate feed path into

   an bus feeder with a potential

   current burden equal to the alternator

   output. The feeder needs to be beefed

   up to 10AWG, the S704 relay replaced

   with something more robust and you

   need to reconsider sizes and placment

   of feeder fuses.



   Let's back up and review the value

   for wiring other than what's shown

   in Z-12? 



 

 

   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Jan 13, 2019 10:56 am Post subject: Basic Elec. Diagram -critique pls

At 06:06 AM 1/13/2019, you wrote:

  	  Quote: 	
		  Igor,



 What are you going to connect to your essential bus? Do you need it at all? I started with a wiring scheme like you have and eliminated the ebus when I realized that, in case of a primary alternator failure, I could simply turn off the pitot heat and landing lights. That reduces the current draw below 30A. 	


   Exactly what happens in a TC aircraft

   with the sb alternator option (z-12).



 

   Bob . . .

supik

Joined: 22 Aug 2018
Posts: 70

Posted: Sun Jan 13, 2019 11:57 am Post subject: Re: Basic Elec. Diagram -critique pls

 	  art(at)zemon.name wrote: 	
		  Igor,

What are you going to connect to your essential bus? Do you need it at all? I started with a wiring scheme like you have and eliminated the ebus when I realized that, in case of a primary alternator failure, I could simply turn off the pitot heat and landing lights. That reduces the current draw below 30A.

    -- Art Z.



	




Art, for IFR in Europe we have to carry dual Nav/Coms and DME. With schedding Pitot heat and Land lights I would be still at 31amps with typical load only. The ESS BUS shall give me a quick shedding option to run only the most necessary equipment for completing the IFR flight safely and stay below 30amps. 



+Redundancy if the main battery contactor fails.

_________________
Igor

RV10 in progress

Kellym

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

Posted: Sun Jan 13, 2019 12:04 pm Post subject: Basic Elec. Diagram -critique pls

Hmm, do you plan on old partial tube type navcoms like the KX170, or are 

you figuring power based on current draw for transmit, which is 

intermittent? Even KX-155 generation navcoms are under 3 amps in receive 

mode. 30 amps is a huge draw. Master relays failure rate is almost 

infinitesimal, if you define failure as not activating, or dropping out. 

Most common fault is developing high resistance, which is still 

functional for flight if you get the engine started.

On 1/13/2019 12:57 PM, supik wrote:

 	  Quote: 	

 art(at)zemon.name wrote:

> Igor,

> What are you going to connect to your essential bus? Do you need it at all? I started with a wiring scheme like you have and eliminated the ebus when I realized that, in case of a primary alternator failure, I could simply turn off the pitot heat and landing lights. That reduces the current draw below 30A.

> Â  Â  -- Art Z.

 Art, for IFR in Europe we have to carry dual Nav/Coms and DME. With schedding Pitot heat and Land lights I would be still at 31amps with typical load only. The ESS BUS shall give me a quick shedding option to run only the most necessary equipment for completing the IFR flight safely and stay below 30amps.

 +Redundancy if the main battery contactor fails.

 --------

 Igor

 RV10 in progress

 Read this topic online here:

 http://forums.matronics.com/viewtopic.php?p=486937#486937

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

supik

Joined: 22 Aug 2018
Posts: 70

Posted: Sun Jan 13, 2019 12:15 pm Post subject: Re: Basic Elec. Diagram -critique pls

 	  nuckolls.bob(at)aeroelect wrote: 	
		  

   E-bus alternate feed on or off?  Why

   run both alternators?



   Driving the e-bus with an alternator

   makes the alternate feed path into

   an bus feeder with a potential

   current burden equal to the alternator

   output. The feeder needs to be beefed

   up to 10AWG, the S704 relay replaced

   with something more robust and you

   need to reconsider sizes and placment

   of feeder fuses.



   Let's back up and review the value

   for wiring other than what's shown

   in Z-12? 



 

 

   Bob . . . 	




My load analysis tells me the main alternator (ALT-1) would be above 80% at standard IFR ops with pitot heat ON. This is a little bit misleading as our rules require to calculate with the equipment's max draw and 1radio in TX mode -stupid but this is the local regulation. To comply with the regulation I have the standby alt (ALT-2) always ON. In case the draw will max out ALT-1, ALT-2 is supposed to take over.



E BUS is fed from both the diode & the relay (which is always on during normal ops). 



You are right, I was too fast without crosschecking the wire sizes & relay's max amp. The battery will be a 24ah Concorde.



What would be the correct fuse placement & size for the EBUS relay/contactor feed?



Bob, thank you very much for sharing your diagrams & knowledge!

_________________
Igor

RV10 in progress

supik

Joined: 22 Aug 2018
Posts: 70

Posted: Sun Jan 13, 2019 12:30 pm Post subject: Re: Basic Elec. Diagram -critique pls

 	  Kellym wrote: 	
		  Hmm, do you plan on old partial tube type navcoms like the KX170, or are 

you figuring power based on current draw for transmit, which is 

intermittent? Even KX-155 generation navcoms are under 3 amps in receive 

mode. 30 amps is a huge draw. Master relays failure rate is almost 

infinitesimal, if you define failure as not activating, or dropping out. 

Most common fault is developing high resistance, which is still 

functional for flight if you get the engine started.

On 1/13/2019 12:57 PM, supik wrote:

 	  Quote: 	

 art(at)zemon.name wrote:

> Igor,

> What are you going to connect to your essential bus? Do you need it at all? I started with a wiring scheme like you have and eliminated the ebus when I realized that, in case of a primary alternator failure, I could simply turn off the pitot heat and landing lights. That reduces the current draw below 30A.

> Â  Â  -- Art Z.

 Art, for IFR in Europe we have to carry dual Nav/Coms and DME. With schedding Pitot heat and Land lights I would be still at 31amps with typical load only. The ESS BUS shall give me a quick shedding option to run only the most necessary equipment for completing the IFR flight safely and stay below 30amps.

 +Redundancy if the main battery contactor fails.

 --------

 Igor

 RV10 in progress

 Read this topic online here:

 http://forums.matronics.com/viewtopic.php?p=486937#486937

In real life, both radios in RX mode with ALL equipment ON I expect to be at 44.7Amps total with a typical load and 19.9Amps on the E BUS. Intermittent load not calculated.

As mentioned before, the local load analysis has to calculate with max draw and 1 radio in TX mode.

_________________
Igor

RV10 in progress

supik

Joined: 22 Aug 2018
Posts: 70

Posted: Sun Jan 13, 2019 1:19 pm Post subject: Re: Basic Elec. Diagram -critique pls

Relay update, v.007



EDIT: Diagram updated in OP

_________________
Igor

RV10 in progress

Last edited by supik on Sun Jan 13, 2019 5:56 pm; edited 1 time in total

supik

Joined: 22 Aug 2018
Posts: 70

Posted: Sun Jan 13, 2019 2:16 pm Post subject: Re: Basic Elec. Diagram -critique pls

v.008  (E BUS updated wire size & protection) peak max draw incl. intermittent draw is 33,7 Amps on the EBUS)



EDIT: Diagram updated in OP

_________________
Igor

RV10 in progress

Last edited by supik on Sun Jan 13, 2019 5:57 pm; edited 1 time in total

art(at)zemon.name
Guest

Posted: Sun Jan 13, 2019 3:23 pm Post subject: Basic Elec. Diagram -critique pls

Igor,

Did you do your load analysis at maximum current draw or at typical current draw? For instance, my VAL COM 2000 radio is 0.50 amps typical but 3.00 amps maximum (when transmitting). In the same vein, my pair of autopilot servos draw 1.80 amps typical and 3.42 maximum. For my BD-4C, my typical draw without pitot heat is 18.57 amps and max is 29.28 amps. 

The Dynon heated pitot tube is 10.00 amps with the heat on. Add 2.00 amps for USB devices and another 1.00 amp for something plugged into a 12V convenience outlet and my typical load is still 31.57 amps, which is darned close to what the B&C backup alternator can deliver at cruise RPM.

I don't know what all equipment you have in your RV-10 but you might be overestimating your power requirements and nudging yourself toward an overly complex electrical system.

    -- Art Z.



-- 

https://CheerfulCurmudgeon.com/"Be kind, for everyone you meet is fighting a hard battle."

supik

Joined: 22 Aug 2018
Posts: 70

Posted: Sun Jan 13, 2019 4:18 pm Post subject: Re: Basic Elec. Diagram -critique pls

 	  art(at)zemon.name wrote: 	
		  Igor,

Did you do your load analysis at maximum current draw or at typical current draw? For instance, my VAL COM 2000 radio is 0.50 amps typical but 3.00 amps maximum (when transmitting). In the same vein, my pair of autopilot servos draw 1.80 amps typical and 3.42 maximum. For my BD-4C, my typical draw without pitot heat is 18.57 amps and max is 29.28 amps. 

The Dynon heated pitot tube is 10.00 amps with the heat on. Add 2.00 amps for USB devices and another 1.00 amp for something plugged into a 12V convenience outlet and my typical load is still 31.57 amps, which is darned close to what the B&C backup alternator can deliver at cruise RPM.

I don't know what all equipment you have in your RV-10 but you might be overestimating your power requirements and nudging yourself toward an overly complex electrical system.

    -- Art Z.



-- 

https://CheerfulCurmudgeon.com/"Be kind, for everyone you meet is fighting a hard battle." 	




Art,



My TYPICAL TOTAL Draw incl. lights, pitot heat & usb.. is recalculated: 48Amps (both Coms RX) -intermittent loads excluded. 



If I turn off pitot heat and land lights, I'll end up with 34.3 TOTAL TYPICAL Draw. With further avionics load shedding I can get below 30Amps of course. Would you suggest that the E BUS architecture makes little sense?

_________________
Igor

RV10 in progress

Last edited by supik on Sun Jan 13, 2019 4:46 pm; edited 1 time in total

supik

Joined: 22 Aug 2018
Posts: 70

Posted: Sun Jan 13, 2019 4:32 pm Post subject: Re: Basic Elec. Diagram -critique pls

My Load Analysis attached:



EDIT: Revised Load Analysis posted in my original post.

_________________
Igor

RV10 in progress

Last edited by supik on Mon Jan 14, 2019 6:45 am; edited 1 time in total

Kellym

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

Posted: Sun Jan 13, 2019 6:53 pm Post subject: Basic Elec. Diagram -critique pls

I don't begin to understand some of the math you are doing on your 

spreadsheet analysis, but I see several areas that I would consider 

differently. Landing lights are not continuous for anything but perhaps 

the last mile of landing. Cockpit LEDs are unlikely to be used during 

flight more than intermittently. Your LED strobe values seem about 

double what mine are.

Using your values I come up with about 24 amps for IFR flight. USB 

charger is not needed during any alternator failure scenario..your 

portable/backup GPS has an internal battery for that situation.



I would get rid of the rudder trim servo. It is not needed. Once you get 

a fixed trim wedge sized for cruise flight, the force needed for climb 

or descent is about the same or less than a Cessna 172. You may consider 

a yaw damper, which will also deal with the slight rudder forces needed 

in non-cruise condition. Putting even a relatively light weight of a 

servo in the rudder will change its harmonic balance, which is 

undesirable. There is a reason that Vans recommends a plastic or wood 

wedge for cruise trim. I also don't use roll trim..just keeping your 

fuel tanks switched at least once an hour is sufficient. Your roll servo 

will handle any minor imbalances.

Unless you regularly fly in visible moisture, you won't use pitot heat 

continuously.

In summary, I think your electrical needs are about 60% what your totals 

show. Your battery will handle the intermittent loads.



On 1/13/2019 5:32 PM, supik wrote:

 	  Quote: 	
		   

 

 My Load Analysis attached:

 

 --------

 Igor

 

 RV10 in progress

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=486948#486948

 

 

 

 

 Attachments:

 

 http://forums.matronics.com//files/loadanalysis_om_ela_v23_lr3c_14_regulators_added_179.pdf

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

art(at)zemon.name
Guest

Posted: Sun Jan 13, 2019 7:13 pm Post subject: Basic Elec. Diagram -critique pls

Igor,

You have certainly done your homework on the load analysis. A few things stand out when I look at the IFR night cruise column, which is 56 amps.

You have the 12 amp pitot heat as a continuous load. I always used pitot heat when the temp was 10C or colder and there was visible moisture. My personal limitations call for pitot heat as a last resort. I am not interested in continued flight into possible icing conditions an my airplane. If I have the pitot heat on, it is temporary, either because I am climbing to known clear air above the clouds or because I am landing.

I don't have my GTN650 (I will install that next fall) but I am very surprised to see a combined load of 1.16 + 2.80 + 4.02 = 8 amps continuous. That's a boatload of power! You've got two radio receivers and a small display screen for continuous load. That 8 amp figure has me scratching my head. My nav and com radios, combined, have a continuous load of just 1 amp.

The audio panel at 2.39 amps is another head scratcher. My PS Engineering audio panel has a continuous load of 0.35 amps.

I also wonder about the continuous load for your display units. You list them at 2 amps each. I have MGL displays which are 10.4 inches diagonally and they only draw 1.20 continuous (each) and 2.25 max.

I don't know the Garmin product line at all so you may well be spot on with your analysis. If you are, and you are willing to fly in conditions when you need your pitot heat for a long time, then I applaud your planning.

You can see the load analysis for my plane on this page: https://drive.google.com/file/d/0BzOP2gb9_3RQSU5qbVN1ckJNOUk/view?usp=sharing

    -- Art Z.



-- 

https://CheerfulCurmudgeon.com/"Be kind, for everyone you meet is fighting a hard battle."

ceengland7(at)gmail.com
Guest

Posted: Sun Jan 13, 2019 7:31 pm Post subject: Basic Elec. Diagram -critique pls

This has come up before, but it's       worthwhile to actually measure current draw for each device. The       mfgrs often are quite conservative (meaning that they overstate)       power demands for their devices. I've measured a few of my       devices, and some draw less than half what their data sheets say.

       

       Charlie

       

       On 1/13/2019 9:12 PM, Art Zemon wrote:

     

      	  Quote: 	
		                                                 Igor,

             

             

             You               have certainly done your homework on the load analysis. A               few things stand out when I look at the IFR night cruise               column, which is 56 amps.

             

             

             You               have the 12 amp pitot heat as a continuous load. I always               used pitot heat when the temp was 10C or colder and there               was visible moisture. My personal limitations call for               pitot heat as a last resort. I am not interested in               continued flight into possible icing conditions an my               airplane. If I have the pitot heat on, it is temporary,               either because I am climbing to known clear air above the               clouds or because I am landing.

             

             

             I               don't have my GTN650 (I will install that next fall) but I               am very surprised to see a combined load of 1.16 + 2.80 +               4.02 = 8 amps continuous. That's a boatload of power!               You've got two radio receivers and a small display screen               for continuous load. That 8 amp figure has me scratching               my head. My nav and com radios, combined, have a               continuous load of just 1 amp.

             

             

             The               audio panel at 2.39 amps is another head scratcher. My PS               Engineering audio panel has a continuous load of 0.35               amps.

             

             

             I               also wonder about the continuous load for your display               units. You list them at 2 amps each. I have MGL displays               which are 10.4 inches diagonally and they only draw 1.20               continuous (each) and 2.25 max.

             

             

             I               don't know the Garmin product line at all so you may well               be spot on with your analysis. If you are, and you are               willing to fly in conditions when you need your pitot heat               for a long time, then I applaud your planning.

             

             

             You               can see the load analysis for my plane on this page: https://drive.google.com/file/d/0BzOP2gb9_3RQSU5qbVN1ckJNOUk/view?usp=sharing

             

             

                               -- Art Z.

           

           

           

           -- 

                                                                                                                                                                                                                                                                                                                                                https://CheerfulCurmudgeon.com/                                                                                  "Be                                           kind, for everyone you meet is                                           fighting a hard battle."

                                     

                                   

                                 

                               

                             

                           

                         

                       

                     

                   

                 

               

             

           

         

       

     	
     

     	          		Virus-free. www.avast.com 		 	 [url=#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2] [/url]

Kellym

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

Posted: Sun Jan 13, 2019 7:34 pm Post subject: Basic Elec. Diagram -critique pls

The GTN 650 in receive mode is 3.5 amps. The screen and GPS receivers 

are 3 amps and the com is .5. I agree the audio panel power is negligible.

I also agree with pitot heat rarely being needed continously, unless 

someone is a lot bolder than I am. I don't know how the RV-10 wing and 

tail perform in icing, and have no intention of finding out.

When I am doing training or maintenance that needs my panel on ground 

power, a 10 amp charger struggles a bit to keep up, but 15 amps more 

than covers the need.



On 1/13/2019 8:12 PM, Art Zemon wrote:

 	  Quote: 	
		   Igor,

 

 You have certainly done your homework on the load analysis. A few things 

 stand out when I look at the IFR night cruise column, which is 56 amps.


	


 	  Quote: 	
		   I don't have my GTN650 (I will install that next fall) but I am very 

 surprised to see a combined load of 1.16 + 2.80 + 4.02 = 8 amps 

 continuous. That's a boatload of power! 

 

 The audio panel at 2.39 amps is another head scratcher. My PS 

 Engineering audio panel has a continuous load of 0.35 amps.

 

 I also wonder about the continuous load for your display units. You list 

 them at 2 amps each. I have MGL displays which are 10.4 inches 

 diagonally and they only draw 1.20 continuous (each) and 2.25 max.

 

 I don't know the Garmin product line at all so you may well be spot on 

 with your analysis. If you are, and you are willing to fly in conditions 

 when you need your pitot heat for a long time, then I applaud your planning.

 

 You can see the load analysis for my plane on this page: 

 https://drive.google.com/file/d/0BzOP2gb9_3RQSU5qbVN1ckJNOUk/view?usp=sharing

 

      -- Art Z.

 

 -- 

 https://CheerfulCurmudgeon.com/

 

 /"Be kind, for everyone you meet is fighting a hard battle."/

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

rick(at)beebe.org
Guest

Posted: Sun Jan 13, 2019 9:39 pm Post subject: Basic Elec. Diagram -critique pls

On 1/13/2019 10:12 PM, Art Zemon wrote:

 	  Quote: 	
		   I don't have my GTN650 (I will install that next fall) but I am very 

 surprised to see a combined load of 1.16 + 2.80 + 4.02 = 8 amps 

 continuous. That's a boatload of power! You've got two radio receivers 

 and a small display screen for continuous load. That 8 amp figure has 

 me scratching my head. My nav and com radios, combined, have a 

 continuous load of just 1 amp.


	




That's the maximum draw at 14 volts. 2.8 on the main connector, 4.0 on 

the com while transmitting, and 1.16 on the nav. "Typical" current draw 

is 1.6, .45 and .60.



--Rick

cluros(at)gmail.com
Guest

Posted: Sun Jan 13, 2019 10:19 pm Post subject: Basic Elec. Diagram -critique pls

Art and Igor,



as someone with about 700 hours of actual time in cloud I feel competent to comment on pitot heat use. There is a reason the POH for any TC aircraft meant to be operated in IFR conditions will have pitot heat on before takeoff. There is a reason many aircraft will give you a warning if they get airborne with the pitot heat off. The problem with turning on pitot heat once you need it is that your first indication of that need may be the loss of all speed indications. While this should not necessarily be fatal for a current and competent pilot, it has proved fatal many times, especially on departure. If you are flying IFR or at night, turn the pitot heat on before takeoff and leave it on until after landing.

I regularly fly IFR in AB and TC aircraft with 1 alternator and 1 battery so as others have stated, I find the design goal of a second alternator that can carry all loads indefinitely to be not useful but no matter what the goal, including continuous use of pitot heat for an IFR aircraft is a must in my books and any aircraft manufacturer's books I have ever seen.

Regards,

Sebastien

On Jan 13, 2019 7:18 PM, "Art Zemon" <art(at)zemon.name (art(at)zemon.name)> wrote: 	  Quote: 	
		  Igor,

You have certainly done your homework on the load analysis. A few things stand out when I look at the IFR night cruise column, which is 56 amps.

You have the 12 amp pitot heat as a continuous load. I always used pitot heat when the temp was 10C or colder and there was visible moisture. My personal limitations call for pitot heat as a last resort. I am not interested in continued flight into possible icing conditions an my airplane. If I have the pitot heat on, it is temporary, either because I am climbing to known clear air above the clouds or because I am landing.

I don't have my GTN650 (I will install that next fall) but I am very surprised to see a combined load of 1.16 + 2.80 + 4.02 = 8 amps continuous. That's a boatload of power! You've got two radio receivers and a small display screen for continuous load. That 8 amp figure has me scratching my head. My nav and com radios, combined, have a continuous load of just 1 amp.

The audio panel at 2.39 amps is another head scratcher. My PS Engineering audio panel has a continuous load of 0.35 amps.

I also wonder about the continuous load for your display units. You list them at 2 amps each. I have MGL displays which are 10.4 inches diagonally and they only draw 1.20 continuous (each) and 2.25 max.

I don't know the Garmin product line at all so you may well be spot on with your analysis. If you are, and you are willing to fly in conditions when you need your pitot heat for a long time, then I applaud your planning.

You can see the load analysis for my plane on this page: https://drive.google.com/file/d/0BzOP2gb9_3RQSU5qbVN1ckJNOUk/view?usp=sharing

    -- Art Z.



-- 

https://CheerfulCurmudgeon.com/"Be kind, for everyone you meet is fighting a hard battle."

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