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Opinions of electrical layout please

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Av8rrob

Joined: 24 Mar 2017
Posts: 7

Posted: Sat Feb 23, 2019 11:00 am Post subject: Opinions of electrical layout please

Here's my general layout that I came up with.  Soliciting opinions.



Thanks

RV-14 electrical-2.jpg

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nuckolls.bob(at)aeroelect
Guest

Posted: Sat Feb 23, 2019 2:54 pm Post subject: Opinions of electrical layout please

At 01:00 PM 2/23/2019, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "Av8rrob" <av8rrob(at)gmail.com>



 Here's my general layout that I came up with.  Soliciting opinions.



 Thanks



 



 

 Read this topic online here:



  http://forums.matronics.com/viewtopic.php?p=487770#487770



 



 

 Attachments: 



  http://forums.matronics.com//files/rv_14_electrical_2_813.jpg 	


   Can you share the line of reasoning

   suggesting that the above architecture has a

   lower risk factor than Z-12?



 

 

   Bob . . .

Av8rrob

Joined: 24 Mar 2017
Posts: 7

Posted: Sat Feb 23, 2019 3:18 pm Post subject: Re: Opinions of electrical layout please

I guess my reasoning for the few modifications to the z-12 are as follows. 



Avionics bus powered by either ess or main bus for easy load shedding. 

Stanby alternator left the on position in flight (lower voltage output) and wired thru a DPDT switch with the IBBS backup battery for brownout and emergency protection for vital flight instruments. 



My procedure would be to power up with;

Standby bat on (check voltage)

Main bat on (check voltage)

Ign on

Start engine 

Stanby alt on (check voltage)

Main alt on (check voltage)

Avionics on

user9253

Joined: 28 Mar 2008
Posts: 1924
Location: Riley TWP Michigan

Posted: Sat Feb 23, 2019 4:41 pm Post subject: Re: Opinions of electrical layout please

What is the backup plan in case the avionics switch fails?

Why have an avionics switch?

How much leakage current flows though the 25 amps alternator when

everything is off?  Is it enough to run the battery down over time?

Can the IBBS battery be charged when the standby alternator is on?

In case of smoke in the cockpit, can both the IBBS battery and the

standby alternator be shut off?

Has the Earth-X battery been sized to accept full alternator output?

Is that a resistor or current shunt in series with the 60 amp alternator output?

_________________
Joe Gores

melvinke(at)coho.net
Guest

Posted: Sat Feb 23, 2019 5:17 pm Post subject: Opinions of electrical layout please

 	  Quote: 	
		   On Feb 23, 2019, at 4:41 PM, user9253 <fransew(at)gmail.com> wrote:

 

 

 

 What is the backup plan in case the avionics switch fails?

 Why have an avionics switch?

 How much leakage current flows though the 25 amps alternator when

 everything is off?  Is it enough to run the battery down over time?

 Can the IBBS battery be charged when the standby alternator is on?

 In case of smoke in the cockpit, can both the IBBS battery and the

 standby alternator be shut off?

 Has the Earth-X battery been sized to accept full alternator output?

 Is that a resistor or current shunt in series with the 60 amp alternator output?

 

 --------

 Joe Gores

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=487780#487780

melvinke(at)coho.net
Guest

Posted: Sat Feb 23, 2019 5:18 pm Post subject: Opinions of electrical layout please

 	  Quote: 	
		   On Feb 23, 2019, at 4:41 PM, user9253 <fransew(at)gmail.com> wrote:

 

 

 

 What is the backup plan in case the avionics switch fails?

 Why have an avionics switch?

 How much leakage current flows though the 25 amps alternator when

 everything is off?  Is it enough to run the battery down over time?

 Can the IBBS battery be charged when the standby alternator is on?

 In case of smoke in the cockpit, can both the IBBS battery and the

 standby alternator be shut off?

 Has the Earth-X battery been sized to accept full alternator output?

 Is that a resistor or current shunt in series with the 60 amp alternator output?

 

 --------

 Joe Gores

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=487780#487780

Av8rrob

Joined: 24 Mar 2017
Posts: 7

Posted: Sat Feb 23, 2019 7:08 pm Post subject: Re: Opinions of electrical layout please

 	  user9253 wrote: 	
		  What is the backup plan in case the avionics switch fails?

Why have an avionics switch?

How much leakage current flows though the 25 amps alternator when

everything is off?  Is it enough to run the battery down over time?

Can the IBBS battery be charged when the standby alternator is on?

In case of smoke in the cockpit, can both the IBBS battery and the

standby alternator be shut off?

Has the Earth-X battery been sized to accept full alternator output?

Is that a resistor or current shunt in series with the 60 amp alternator output? 	




If the avionics switch fails, then the only loss is some non-essential avionics.  I like the availability to load shed. I guess if i was stranded with a broken switch I could just had wire the avionics bus to the main bus to get home.  Excuse my ignorance but Im not aware of leakage current of a switched off alternator, can you explain further?  The IBBS battery will charge as long as the master battery is switched on which will allow the main bus to be powered by the alt, followed by the standby alt, followed by the main battery. Yes, if there is smoke, both master and backup switches will be turned off. This will leave the ignition running off its own dedicated battery (1 hr) and the G5 running off its own battery.  I cant speak about earth x batteries issues (still need to talk to them). Just call it a battery for now.  That was my attempt at a current shunt in series with the alt. 



Thanks for your thoughts. Keep em coming.

user9253

Joined: 28 Mar 2008
Posts: 1924
Location: Riley TWP Michigan

Posted: Sat Feb 23, 2019 8:23 pm Post subject: Re: Opinions of electrical layout please

I think that there should be some way to disconnect the standby alternator "B"

lead from the battery.  The internal diodes might not leak much current.  But in 

case of an imminent forced landing, all electrical power should be shut off as 

close to the source as possible.  Always hot wires could make sparks and start a 

fire.

 Unlike lead-acid batteries, Earth-X batteries do not have very much internal 

resistance to limit charging current.  If the battery is run down, it will accept 

everything that the alternator can supply, i.e. 60+ amps.  The size of the lithium 

battery needs to determined based on the alternator size.

_________________
Joe Gores

Av8rrob

Joined: 24 Mar 2017
Posts: 7

Posted: Sat Feb 23, 2019 9:41 pm Post subject: Re: Opinions of electrical layout please

Excellent point about the hot wire to the alternator. Any recommendations of how I can do that best?

user9253

Joined: 28 Mar 2008
Posts: 1924
Location: Riley TWP Michigan

Posted: Sun Feb 24, 2019 9:19 am Post subject: Re: Opinions of electrical layout please

Attached is a way to minimize the length of hot wires when switches are shut off.

Av8rrob.jpg

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_________________
Joe Gores

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Feb 24, 2019 2:12 pm Post subject: Opinions of electrical layout please

 	  Quote: 	
		  

 If the avionics switch fails, then the only loss is some non-essential avionics.

 I like the availability to load shed. 	


   Have you conducted a Failure Mode Effects

   Analysis in concert with a Load Analysis?



   Under what operating condition + failure

   will you need to load-shed? You have a

   25A standby alternator that should carry

   lots of electro-whizzies. It may well

   be that the load-shedding protocols are

   little more complicated that opening

   the avionics switch.



   Dropping a couple of 'big' loads

   as part of the Plan-B protocol

   seems far more practical than

   driving up complexity with the

   switch/diode array you've illustrated.



  	  Quote: 	
		   I guess if i was stranded with a broken switch I 

  could just had wire the avionics bus to the main

  bus to get home. 	


   It may well be that the avionics switch

   is and un-necessary antagonist to

   risk of failure.



  	  Quote: 	
		  Excuse my ignorance but Im not aware of leakage

 current of a switched off alternator, can you

 explain further? 	


   Not a concern . . . there are tens of

   millions of alternators hard-wired to

   the battery of cars with no deleterious

   effect. "Leakage" back through the alternator

   diodes is vanishingly small.



  	  Quote: 	
		  The IBBS battery will charge as long as the master

 battery is switched on which will allow the main bus

 to be powered by the alt, followed by the standby alt,

 followed by the main battery. Yes, if there is smoke, both master and backup switches will be turned off. This will leave the ignition running off its own dedicated battery (1 hr) and the G5 running off its own battery.  I cant speak about earth x batteries issues (still need to talk to them). Just call it a battery for now.  That was my attempt at a current shunt in series with the alt. 	


   Let's do the math and FMEA first. What

   gizmos are least likely to be useful

   during a main alternator failure?



   What is the configuration of your

   ignition system? Why a separate

   battery?



 

 

   Bob . . .

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