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External Power and electrical system isolation

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michele.delsol(at)microsi
Guest

Posted: Thu Jul 13, 2006 11:57 am Post subject: External Power and electrical system isolation

Listers,



I have been planning on adding external power to my system (one alternator,

one battery, PMag IO360). My original design was pretty simple, hook it

straight onto the battery such as one does when jump starting a car. Then I

added a relay so that the external power terminals would not be hot when not

connected to external power. Then some knowledgeable fellow builders told me

that I should only use external power for starting the engine – nothing

else. Then some other knowledgeable builders told me that I could install a

cigar lighter jack in parallel as an external power connector for recharging

the battery. Then there was the issue as to external power not being clean

DC current and consequently liable to play havoc with some of my sensitive

equipment. Based on this I proceeded to design a circuit which would

automatically disconnect all electricals except for the starter solenoid,

current to the PMags and current to my fuel pump. Whereupon another

knowledgeable person suggested that I should remember the KISS principle – I

may be over designing my system.



What do you guys suggest – isolate my electrical system when external power

is hot or just hook it up onto the battery via a relay?



Thanks,

Michele Delsol

RV8 Fuselage

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harley(at)AgelessWings.co
Guest

Posted: Thu Jul 13, 2006 1:33 pm Post subject: External Power and electrical system isolation

Afternoon, Michele

 >>hook it straight onto the battery such as one does when jump starting a car<<

 I'm not familiar with an RV8, as I have a Long EZ (hangar neighbor has an RV6, though), but my philosophy is as you said...the KISS principal.  Fewer plugs, relays, switches, cables and wires means less weight in the plane and fewer things to fail and possibly cause problems with other devices even when the ground power is NOT connected. 

 >>so that the external power terminals would not be hot when not connected to external power.<< 

 You lost me here.  The external terminals? Can't you just clip a trickle charger directly onto the battery? Leave the master switch off when charging, and you should be fine. Remove the charger when flying and you have a nice, light, safe craft! <G>

 That way, you'll always have a full battery, and should never have problems having enough juice to start the plane. 

 Harley Dixon

 Long EZ N28EZ

 Canandaigua, NY

 Michèle MS wrote:  	  Quote: 	
		      	  Quote: 	
		  --> AeroElectric-List message posted by: =?iso-8859-1?Q?Mich=E8le_MS?= <michele.delsol(at)microsigma.fr> (michele.delsol(at)microsigma.fr)

Listers,

I have been planning on adding external power to my system (one alternator,

one battery, PMag IO360). My original design was pretty simple, hook it

straight onto the battery such as one does when jump starting a car. Then I

added a relay so that the external power terminals would not be hot when not

connected to external power. Then some knowledgeable fellow builders told me

that I should only use external power for starting the engine – nothing

else. Then some other knowledgeable builders told me that I could install a

cigar lighter jack in parallel as an external power connector for recharging

the battery. Then there was the issue as to external power not being clean

DC current and consequently liable to play havoc with some of my sensitive

equipment. Based on this I proceeded to design a circuit which would

automatically disconnect all electricals except for the starter solenoid,

current to the PMags and current to my fuel pump. Whereupon another

knowledgeable person suggested that I should remember the KISS principle – I

may be over designing my system.

What do you guys suggest – isolate my electrical system when external power

is hot or just hook it up onto the battery via a relay?

Thanks,

Michele Delsol

RV8 Fuselage

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FLYaDIVE(at)aol.com
Guest

Posted: Sat Jul 15, 2006 1:32 am Post subject: External Power and electrical system isolation

In a message dated 7/13/06 3:59:57 PM Eastern Daylight Time, 

michele.delsol(at)microsigma.fr writes:



 	  Quote: 	
		   What do you guys suggest â€“ isolate my electrical system when external power

  is hot or just hook it up onto the battery via a relay?

  

  Thanks,

  Michele Delsol

  RV8 Fuselage

===========================
	


Michele:



The first question you have to ask yourself is: "What do I want the external 

power for?"

If your answer is STARTING then all that is required is a connection - relay 

to act as a MASTER RELAY and supply power to the Starter Relay and conversely 

to the STARTER.  Isolating the rest of the panel and electronics.  You can get 

that circuit from any GA manual Cessna, Piper or Grumman.  That to me is the 

K.I.S.S. M.E. principal.  Now if you want a THREE function power hookup source 

for:

1 - Running a handheld or GPS

2 - Running your electronics for testing, or

3 - Doing a LOW LEVEL charge, such as charging the battery using a solar 

panel ... The just hook up a cigarette lighter directly to the battery.

This is the system I have hooked up in the RV-6A.

It is GREAT when you have an electrical problem and have to shut down the 

MASTER.  It gives you power for the GPS [Navigation] and a handheld 

[Communication].  Oh, did you remember to install a quick disconnect for the antenna so you 

can hook up the handheld?



Barry

"Chop'd Liver"

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michele.delsol(at)microsi
Guest

Posted: Thu Jul 20, 2006 9:47 am Post subject: External Power and electrical system isolation

Thanks Harley and Barry - shall have to do more thinking and make the system

simpler - your input definitely helps.



Michele



--

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