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Circuit protection for backup alternator

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Ed Godfrey

Joined: 05 May 2009
Posts: 47

Posted: Mon Apr 10, 2017 8:31 am Post subject: Circuit protection for backup alternator

Bob,

    I am building an RV10 and installing a B&C 410H backup alternator. I 

have installed an ANL circuit protection next to the battery behind the 

baggage compartment, to protect the #6 wire that I have going forward, 

along the lines of your Z-13/8 schematic. But I was concerned about the 

output of the alternator going aft. I have a contactor on the firewall 

for the output of the alternator and I was considering installing a 

fusible link between the alternator and the contactor for protection. 

Are there any issues that you might see with a setup like this? Thanks.



Ed Godfrey

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Apr 10, 2017 8:40 am Post subject: Circuit protection for backup alternator

At 11:29 AM 4/10/2017, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: Ed Godfrey <egodfrey(at)ameritech.net>



 Bob,

    I am building an RV10 and installing a B&C 410H backup alternator. I have installed an ANL circuit protection next to the battery behind the baggage compartment, to protect the #6 wire that I have going forward, along the lines of your Z-13/8 schematic. But I was concerned about the output of the alternator going aft. I have a contactor on the firewall for the output of the alternator and I was considering installing a fusible link between the alternator and the contactor for protection. Are there any issues that you might see with a setup like this? Thanks. 	


   No . . . the alternator is incapable of delivering

   current needed to put the b-lead at risk.



 

 

   Bob . . .

Kellym

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

Posted: Mon Apr 10, 2017 12:31 pm Post subject: Circuit protection for backup alternator

IMHO you are getting things backwards. You do not need protection for 

the heavy wire from the battery to the firewall/starter solenoid. 

However, that cable should be #4 minimum, and better #2.

Use the ANL to protect the B lead from the alternator to the main bus, 

with the ammeter shunt either right above or below it on the firewall.

Your #6 (or # is appropriate for that B lead.

Kelly

RV-10 40866, flying



On 4/10/2017 9:29 AM, Ed Godfrey wrote:

 	  Quote: 	
		   

 <egodfrey(at)ameritech.net>



 Bob,

    I am building an RV10 and installing a B&C 410H backup alternator. I

 have installed an ANL circuit protection next to the battery behind the

 baggage compartment, to protect the #6 wire that I have going forward,

 along the lines of your Z-13/8 schematic. But I was concerned about the

 output of the alternator going aft. I have a contactor on the firewall

 for the output of the alternator and I was considering installing a

 fusible link between the alternator and the contactor for protection.

 Are there any issues that you might see with a setup like this? Thanks.



 Ed Godfrey

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

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Apr 10, 2017 1:06 pm Post subject: Circuit protection for backup alternator

 	  Quote: 	
		    	  Quote: 	
		  I have a contactor on the firewall for the output of the alternator and I was considering installing a fusible link between the alternator and the contactor for protection. Are there any issues that you might see with a setup like this? Thanks. 	
	


   You probably don't need that long #6 feeder . . .

   you can feed the alternator's output into

   the system at the starter contactor on the

   firewall. A miniANL on a fuseblock or a

   MAXI-blade in an in-line fuse holder could

   be pressed into protection of this circuit

   and eliminate the long wire run.



 

   Bob . . .

Ed Godfrey

Joined: 05 May 2009
Posts: 47

Posted: Mon Apr 10, 2017 2:43 pm Post subject: Circuit protection for backup alternator

Bob,

         Following the Z-13/8, I am connecting up the backup alternator     to the hot side of the battery contactor. With the distance that the     power is traveling, I calculated that the #6 wire would be the best     choice. Did I choose wrong?

     

     Ed

     

     On 4/10/2017 4:04 PM, Robert L.       Nuckolls, III wrote:

     

      	  Quote: 	
		          	  Quote: 	
		            	  Quote: 	
		  I             have a contactor             on the firewall for the output of the alternator and I was             considering             installing a fusible link between the alternator and the             contactor for             protection. Are there any issues that you might see with a             setup like             this? Thanks. 	
       	
       

         You probably don't need that long #6 feeder . . .

         you can feed the alternator's output into

         the system at the starter contactor on the

         firewall. A miniANL on a fuseblock or a

         MAXI-blade in an in-line fuse holder could

         be pressed into protection of this circuit

         and eliminate the long wire run.

       

                

             Bob . . .

Mauledriver(at)nc.rr.com
Guest

Posted: Mon Apr 10, 2017 2:55 pm Post subject: Circuit protection for backup alternator

Â I have been flying my RV-10 with a 2       battery/2 alternator/2 bus Z-14 for 5+ years.Â  Just for reference       purposes my configuration includes:

                Both batteries and battery contactors are installed behind           baggage compartment         
2 AWG wire used to to all contactors including a run forward           of the firewall for the starter contactor and the main           alternator

                  
8 AWG wire used for runs to 2 fuse blocks on cockpit           sidewalls and for run from SD20 alternator and it's battery           contactor in the rear         
ANL current limiters installed on firewall close to           alternators for both B leads         
(there is no protection on runs from battery contactors in           rear to fuse blocks and starter in the front)              I wouldn't do it any differently if I did it again.

       

       

       On 4/10/2017 12:29 PM, Ed Godfrey wrote:

     

      	  Quote: 	
		  -->       AeroElectric-List message posted by: Ed Godfrey       <egodfrey(at)ameritech.net> (egodfrey(at)ameritech.net)       

       

       Bob,       

       Â Â  I am building an RV10 and installing a B&C 410H backup       alternator. I have installed an ANL circuit protection next to the       battery behind the baggage compartment, to protect the #6 wire       that I have going forward, along the lines of your Z-13/8       schematic. But I was concerned about the output of the alternator       going aft. I have a contactor on the firewall for the output of       the alternator and I was considering installing a fusible link       between the alternator and the contactor for protection. Are there       any issues that you might see with a setup like this? Thanks.       

       

       Ed Godfrey       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

     	
     



          	          		Virus-free. www.avast.com

Kellym

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

Posted: Mon Apr 10, 2017 4:20 pm Post subject: Circuit protection for backup alternator

Normally, I would agree. However, the RV-10 requires the main battery 

behind the baggage compartment for W&B, so it does require one long 

heavy lead from the battery to the firewall. IMHO it should be no less 

than #4, and really should be #2 for good starter performance, given the 

over 10 ft run from battery to starter. Ground is handled through the 

aluminum airframe for the battery. Very conventional with master relay 

at the battery and starter relay on firewall near where the battery 

heavy lead comes through. Vans publishes a basic wiring diagram that is 

very conventional for a VFR aircraft, that gives a good starting point 

for wire sizes and physical locations. It is easy to modify to meet 

goals for endurance bus, redundancy, etc.

On 4/10/2017 2:04 PM, Robert L. Nuckolls, III wrote:

 	  Quote: 	
		  >> I have a contactor on the firewall for the output of the alternator

>> and I was considering installing a fusible link between the

>> alternator and the contactor for protection. Are there any issues

>> that you might see with a setup like this? Thanks.

   You probably don't need that long #6 feeder . . .

   you can feed the alternator's output into

   the system at the starter contactor on the

   firewall. A miniANL on a fuseblock or a

   MAXI-blade in an in-line fuse holder could

   be pressed into protection of this circuit

   and eliminate the long wire run.

   Bob . . .

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

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Apr 10, 2017 4:29 pm Post subject: Circuit protection for backup alternator

At 05:39 PM 4/10/2017, you wrote:

  	  Quote: 	
		  Bob,

     Following the Z-13/8, I am connecting up the backup alternator to the hot side of the battery contactor. With the distance that the power is traveling, I calculated that the #6 wire would be the best choice. Did I choose wrong? 	


   How about Z12 instead? Tie both alternators to

   the bus structure at the hot side of the starter

   contactor.



   Just use the smaller alternator like a stand-by

   device like hundreds of TC aircraft.  Which

   regulator are you using on the small alternator?



   Z-13/8 was crafted specifically for minimizing loads

   on the diminutive SD-8 alternator with bypassing

   the battery contactor. The extra snort

   available from the larger wound field makes this

   a moot point . . . Z12 would simplify your wiring.



 



 

   Bob . . .

Ed Godfrey

Joined: 05 May 2009
Posts: 47

Posted: Mon Apr 10, 2017 5:35 pm Post subject: Circuit protection for backup alternator

Bob,

         I am using the SB1B-14 regulator.

     

     Ed

     

     On 4/10/2017 7:26 PM, Robert L.       Nuckolls, III wrote:

     

      	  Quote: 	
		         At 05:39 PM 4/10/2017, you wrote:

               	  Quote: 	
		  Bob,

               Following the Z-13/8, I am connecting up the backup           alternator to the hot side of the battery contactor. With the           distance           that the power is traveling, I calculated that the #6 wire           would be the           best choice. Did I choose wrong? 	
       

         How about Z12 instead? Tie both alternators to

         the bus structure at the hot side of the starter

         contactor.

       

         Just use the smaller alternator like a stand-by

         device like hundreds of TC aircraft.  Which

         regulator are you using on the small alternator?

       

         Z-13/8 was crafted specifically for minimizing loads

         on the diminutive SD-8 alternator with bypassing

         the battery contactor. The extra snort

         available from the larger wound field makes this

         a moot point . . . Z12 would simplify your wiring.

       

       

       

                

             Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Apr 11, 2017 7:31 am Post subject: Circuit protection for backup alternator

At 08:33 PM 4/10/2017, you wrote:

  	  Quote: 	
		  Bob,

     I am using the SB1B-14 regulator. 	


   Okay . . . I'd recommend a Z-12 with

   endurance bus. Much simpler in terms

   of wire and not significantly less

   robust.



 

 

   Bob . . .

Ed Godfrey

Joined: 05 May 2009
Posts: 47

Posted: Tue Apr 11, 2017 7:44 am Post subject: Circuit protection for backup alternator

Bob,

         Thanks for the insight. I will review the Z12 ans see if I want     to make the changes. Also, thank you to those others who offered up     advice. 

     

     Ed

     

     On 4/11/2017 10:27 AM, Robert L.       Nuckolls, III wrote:

     

      	  Quote: 	
		         At 08:33 PM 4/10/2017, you wrote:

               	  Quote: 	
		  Bob,

               I am using the SB1B-14           regulator. 	
       

         Okay . . . I'd recommend a Z-12 with

         endurance bus. Much simpler in terms

         of wire and not significantly less

         robust.

       

       

                

             Bob . . .

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