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wright.dennis(at)icloud.c
Guest

Posted: Tue Jul 05, 2016 7:39 pm Post subject: Dead battery

From:  Dennis Wright



 	  Quote: 	
		   Trying to figure out if I have an issue with my electrical system in my sonex or just bad luck. Have had multiple battery failures. Here's the situation.  Battery is an odyssey pc625. , 12 volt.   Engine is an Aerovee 2180.  First flight was in December 2015.  Battery at that time was about 2.5 years old. During the time before first flight had to charge batter several times due to minimal use. After about 5 hrs of flying started experiencing a dead battery. Would charge, fly, and next day battery would be dead again. Figured it was due to age and fact that battery had sat uncharged for prolonged periods.  Replaced battery. After about 15 hrs flying time (about 3 months) on new battery, went dead.  Tried to charge but would not hold a charge. Had battery tested and showed that it had a bad cell.   Replaced battery.  After about 25 hrs (about 3 months), another dead battery and will not hold a charge   Each time everything is working perfect one day and dead the next. Not blo!

 wing any fuses, no smoking wires,  system voltage is showing 13.5 volts when I'm flying.  Have not checked to see if there is a load on the battery when the battery solenoid is open but do not have anything connected on the battery side of the solenoid so unless the solenoid is bad, shouldn't have any load when off.  Would appreciate any thoughts on what the problem might be or where to start to figure it out.  

 

 From:  Dennis Wright

ceengland7(at)gmail.com
Guest

Posted: Tue Jul 05, 2016 7:54 pm Post subject: Dead battery

On 7/5/2016 10:37 PM, Dennis Wright wrote:

 	  Quote: 	
		   



 From:  Dennis Wright



> Trying to figure out if I have an issue with my electrical system in my sonex or just bad luck. Have had multiple battery failures. Here's the situation.  Battery is an odyssey pc625. , 12 volt.   Engine is an Aerovee 2180.  First flight was in December 2015.  Battery at that time was about 2.5 years old. During the time before first flight had to charge batter several times due to minimal use. After about 5 hrs of flying started experiencing a dead battery. Would charge, fly, and next day battery would be dead again. Figured it was due to age and fact that battery had sat uncharged for prolonged periods.  Replaced battery. After about 15 hrs flying time (about 3 months) on new battery, went dead.  Tried to charge but would not hold a charge. Had battery tested and showed that it had a bad cell.   Replaced battery.  After about 25 hrs (about 3 months), another dead battery and will not hold a charge   Each time everything is working perfect one day and dead the next. Not b!

   lo!

> wing any fuses, no smoking wires,  system voltage is showing 13.5 volts when I'm flying.  Have not checked to see if there is a load on the battery when the battery solenoid is open but do not have anything connected on the battery side of the solenoid so unless the solenoid is bad, shouldn't have any load when off.  Would appreciate any thoughts on what the problem might be or where to start to figure it out.

>

> From:  Dennis Wright

13.5v won't charge the battery.

peter(at)sportingaero.com
Guest

Posted: Tue Jul 05, 2016 9:56 pm Post subject: Dead battery

Agree, charging voltage should be more like 14.2 to 14.5 v, especially for an Odessey type battery. On 6 Jul 2016 05:07, "Charlie England" <ceengland7(at)gmail.com (ceengland7(at)gmail.com)> wrote: 	  Quote: 	
		  --> AeroElectric-List message posted by: Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)>

 

 On 7/5/2016 10:37 PM, Dennis Wright wrote:

  	  Quote: 	
		   --> AeroElectric-List message posted by: Dennis Wright <wright.dennis(at)icloud.com (wright.dennis(at)icloud.com)>

 

 

 

 From:Â  Dennis Wright

 

  	  Quote: 	
		   Trying to figure out if I have an issue with my electrical system in my sonex or just bad luck. Have had multiple battery failures. Here's the situation.Â  Battery is an odyssey pc625. , 12 volt.Â  Â Engine is an Aerovee 2180.Â  First flight was in December 2015.Â  Battery at that time was about 2.5 years old. During the time before first flight had to charge batter several times due to minimal use. After about 5 hrs of flying started experiencing a dead battery. Would charge, fly, and next day battery would be dead again. Figured it was due to age and fact that battery had sat uncharged for prolonged periods.Â  Replaced battery. After about 15 hrs flying time (about 3 months) on new battery, went dead.Â  Tried to charge but would not hold a charge. Had battery tested and showed that it had a bad cell.Â  Â Replaced battery.Â  After about 25 hrs (about 3 months), another dead battery and will not hold a chargeÂ  Â Each time everything is working perfect one day and dead the next. Not !

 	
	
 b!

  	  Quote: 	
		   Â  lo!

  	  Quote: 	
		   wing any fuses, no smoking wires,Â  system voltage is showing 13.5 volts when I'm flying.Â  Have not checked to see if there is a load on the battery when the battery solenoid is open but do not have anything connected on the battery side of the solenoid so unless the solenoid is bad, shouldn't have any load when off.Â  Would appreciate any thoughts on what the problem might be or where to start to figure it out.

 

 From:Â  Dennis Wright

 

 

 	
	
 13.5v won't charge the battery.

 

 

 

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Mauledriver(at)nc.rr.com
Guest

Posted: Wed Jul 06, 2016 7:16 am Post subject: Dead battery

And I can confirm, that if your system       charging voltage is 13.5, you will kill your battery in amazing       short order.

       

       You have to get it up to 14.5 or so.Â  In the mean time, charge it       on a proper charger (for AGM Batts) between flights.

       

       Bill "killer of at least 3" Watson

       

       On 7/6/2016 1:53 AM, Peter Pengilly wrote:

     

      	  Quote: 	
		         

Agree, charging voltage should be more like 14.2 to         14.5 v, especially for an Odessey type battery.       

       

     	
     



            	 		 			 				 			 		 		 			

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alec(at)alecmyers.com
Guest

Posted: Wed Jul 06, 2016 8:50 am Post subject: Dead battery

Just to add one more datapoint, I'd been running on a charging voltage of 13.2 to 13.4 for three years+ on a Comcorde sealed gel battery - and while it has been sluggish starts for the past three Canadian winters I don't see any evidence that it's damaged, certainly not dead.



On Jul 6, 2016, at 11:15, Bill Watson <Mauledriver(at)nc.rr.com (Mauledriver(at)nc.rr.com)> wrote:

                   And I can confirm, that if your system       charging voltage is 13.5, you will kill your battery in amazing       short order.

       

       You have to get it up to 14.5 or so.  In the mean time, charge it       on a proper charger (for AGM Batts) between flights.

       

       Bill "killer of at least 3" Watson

       

       On 7/6/2016 1:53 AM, Peter Pengilly wrote:

     

      	  Quote: 	
		         

Agree, charging voltage should be more like 14.2 to         14.5 v, especially for an Odessey type battery.       

       

     	
     



         



   	 		 			 				 			 		 		 			

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JohnInReno

Joined: 08 Sep 2007
Posts: 150

Posted: Wed Jul 06, 2016 9:45 am Post subject: Dead battery

I have a similar problem with an RV4 that I purchased. 

          

Dead battery.

       Discovered field wire broken - repaired.

       Field wire is jumpered directly to the alternator output. No fuse,       cb, or switch.

       The alternator appears to be internally regulated.

          

I am seeing no more than 13.5 volts.

          With no load at all on the field wire, is that what is keeping the     voltage down?

     

     john

     

     On 7/6/2016 8:15 AM, Bill Watson wrote:

     

      	  Quote: 	
		                And I can confirm, that if your         system charging voltage is 13.5, you will kill your battery in         amazing short order.

         

         You have to get it up to 14.5 or so.Â  In the mean time, charge         it on a proper charger (for AGM Batts) between flights.

         

         Bill "killer of at least 3" Watson

         

         On 7/6/2016 1:53 AM, Peter Pengilly wrote:

       

        	  Quote: 	
		           

Agree, charging voltage should be more like 14.2 to           14.5 v, especially for an Odessey type battery.         

         

       	
       



              

       

                                                                                               

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_________________
John Morgensen
RV-9A - Born on July 3, 2013
RV4 - for sale

Mauledriver(at)nc.rr.com
Guest

Posted: Wed Jul 06, 2016 10:29 am Post subject: Dead battery

On 7/6/2016 1:44 PM, John Morgensen wrote:

 	  Quote: 	
		  

 I have a similar problem with an RV4 that I purchased.



 Dead battery.

 Discovered field wire broken - repaired.

 Field wire is jumpered directly to the alternator output. No fuse, cb, 

 or switch.

 The alternator appears to be internally regulated.



 I am seeing no more than 13.5 volts.



 With no load at all on the field wire, is that what is keeping the 

 voltage down?

Well, charging at 13.5 will kill an Odyssey AGM battery.
	




I have a regulator and alternator - my regulator is adjustable and 

needed to be set to 14.5 to get a normal charge on my Odysseys.



In general, 13.5 is fine for lead acid batteries.



I'm doing this from memory and experience but the place to look is the 

spec sheets.



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user9253

Joined: 28 Mar 2008
Posts: 1926
Location: Riley TWP Michigan

Posted: Wed Jul 06, 2016 1:12 pm Post subject: Re: Dead battery

JohnInReno,

A bad connection could be causing low voltage.  Check both ends of the wire from the alternator "B" terminal.  Pull hard on the terminals to make sure they are solid with no corrosion.  Also check the engine ground wire.  The engine mount should NOT be part of the ground circuit.

_________________
Joe Gores

nuckolls.bob(at)aeroelect
Guest

Posted: Wed Jul 06, 2016 3:58 pm Post subject: Dead battery

 	  Quote: 	
		  

 I have a regulator and alternator - my regulator is adjustable and needed to be set to 14.5 to get a normal charge on my Odysseys.



 In general, 13.5 is fine for lead acid batteries. 	


   It has never been fine for any version of a lead-acid

   battery.  In fact, low voltage warning systems are

   generally calibrated to come on at or below 13.5

   volts.



   Batteries take on energy at 13.8 and above . . . 14.2

   plus/minus 0.2 volts has been the lead-acid legacy

   setpoint for 70 years or more. B&C sets their regulators

   for 14.5 to 14.6 out the door.



   An alternator producing 13.5 will not charge a battery,

   but it will keep the battery from becoming discharged . . .

   assuming it was charged before flight.



   If the aircraft is stored with a charger/maintainer

   then the engine gets started by a 100% battery. If the

   alternator set-point is only 13.5, then the battery

   doesn't get replenished . . . until it gets connected

   to the charger while parked. Under THIS scenario, the

   battery is happy as a clam and will last a really long

   time.



   Assuming the battery is never supported externally

   for energy replenishment the 13.5v bus won't

   top off a battery that has just started the engine.

   At the same time, the 13.5v bus runs all the electro-

   whizzies just fine.



   Starting a well tuned engine only takes 3-5% of

   a battery's stored energy. So a topped off battery

   can be expected to take you flying for 5-10 times

   before you notice that it's getting 'weak'. Whacking

   it down over a long period of time without replenishment

   eventually produces the "dead battery" syndrome . . .

   storing a battery in a low state of charge is hard

   on its chemistry . . . no matter what kind of lead

   acid battery it is.



   We were presented with a 13.5v bus on a 182 a few

   days ago on a Canadian ship that was suffering the

   effects off high resistance joints and a poorly

   adjusted regulator. His "dead battery" symptoms

   were predictable . . . AGM . . . Flooded . . .

   it doesn't matter.



   The charging system needs attention to get the

   bus up . . . 14.5v is a good target.



 

   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Wed Jul 06, 2016 3:58 pm Post subject: Dead battery

At 12:44 PM 7/6/2016, you wrote:



  	  Quote: 	
		  Dead battery.

 Discovered field wire broken - repaired.

 Field wire is jumpered directly to the alternator output. No fuse, cb, or switch.

 The alternator appears to be internally regulated. 	


   then that is not a 'field' wire . . . it's

   a control line that the automotive ECM talks

   to for turning the alternator off and on.



  	  Quote: 	
		  I am seeing no more than 13.5 volts.

 With no load at all on the field wire, is that what is keeping the voltage down? 	


   If repairing the CONTROL line did not correct

   the problem, then the alternator is broke.



 

   Bob . . .

JohnInReno

Joined: 08 Sep 2007
Posts: 150

Posted: Wed Jul 06, 2016 5:22 pm Post subject: Dead battery

Sorry if I high-jacked the thread. My problem is a lycoming O-320       and it bothers me that there is no fuse, cb, or switch on the       control wire going to the alternator.     

john

          

     On 7/6/2016 4:57 PM, Robert L.       Nuckolls, III wrote:

     

      	  Quote: 	
		         At 12:44 PM 7/6/2016, you wrote:

         

               	  Quote: 	
		  Dead           battery.

         Discovered           field           wire broken - repaired.

           Field wire is jumpered directly to the alternator output. No           fuse, cb, or           switch.

           The alternator appears to be internally           regulated. 	
       

         then that is not a 'field' wire . . . it's

         a control line that the automotive ECM talks

         to for turning the alternator off and on.

       

        	  Quote: 	
		  I am           seeing no more           than 13.5 volts.

           With no load at all on the field wire, is that what is keeping           the           voltage down? 	
       

         If repairing the CONTROL line did not correct

         the problem, then the alternator is broke.

       

                

             Bob . . .

_________________
John Morgensen
RV-9A - Born on July 3, 2013
RV4 - for sale

nuckolls.bob(at)aeroelect
Guest

Posted: Wed Jul 06, 2016 5:39 pm Post subject: Dead battery

At 08:19 PM 7/6/2016, you wrote:



  	  Quote: 	
		  Sorry if I high-jacked the thread. My problem is a lycoming O-320 and it bothers me that there is no fuse, cb, or switch on the control wire going to the alternator. 	




   This is an OBAM aircraft? Do you have an

   alternator on/off switch . . . either as

   a separate device -or- split rocker - etc?



   It is functionally sufficient to simply

   wire the control lead of an internally

   regulated alternator direcdtly to the b-lead

   or other always-hot source . . . this simply

   causes the alternator to come on line as soon

   as the engine starts.



   At the same time, you have no control over

   the alternator . . . if you turn the battery

   switch off, the alternator continues to provide

   output. If you experience an ov condition, there's

   no provisions for bringing the runaway alternator

   to heel.



 

 

   Bob . . .

user9253

Joined: 28 Mar 2008
Posts: 1926
Location: Riley TWP Michigan

Posted: Thu Jul 07, 2016 4:24 am Post subject: Re: Dead battery

Just to emphasize what Bob said, connecting the alternator control wire directly to the "B" terminal is not recommended.  The master switch no longer has control over the electrical system.  It is not a master switch in this case, but is a battery switch.  Shutting off the master switch in flight only disconnects the battery, but does not shut off the electrical system.  Everything will keep working.  If the electrical system needs to be shut off in an emergency like smoke in the cockpit or a fuel leak or high voltage, the only way to accomplish that is to shut off the engine also.  The master switch needs to be placarded, "Inoperative in flight".  The solution is to run the alternator control wire to a panel mounted fused switch.  Doing that will not only eliminate the above problems, but also allow the voltage regulator to monitor actual system voltage instead of alternator output voltage.  They could be different if there is resistance in the alternator wiring.  That resistance could result in lower system voltage even though the alternator is putting out 14+ volts.

_________________
Joe Gores

ceengland7(at)gmail.com
Guest

Posted: Thu Jul 07, 2016 5:11 am Post subject: Dead battery

On Thu, Jul 7, 2016 at 7:24 AM, user9253 <fransew(at)gmail.com (fransew(at)gmail.com)> wrote:

 	  Quote: 	
		  --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com (fransew(at)gmail.com)>

 

 Just to emphasize what Bob said, connecting the alternator control wire directly to the "B" terminal is not recommended.Â  The master switch no longer has control over the electrical system.Â  It is not a master switch in this case, but is a battery switch.Â  Shutting off the master switch in flight only disconnects the battery, but does not shut off the electrical system.Â  Everything will keep working.Â  If the electrical system needs to be shut off in an emergency like smoke in the cockpit or a fuel leak or high voltage, the only way to accomplish that is to shut off the engine also.Â  The master switch needs to be placarded, "Inoperative in flight".Â  The solution is to run the alternator control wire to a panel mounted fused switch.Â  Doing that will not only eliminate the above problems, but also allow the voltage regulator to monitor actual system voltage instead of alternator output voltage.Â  They could be different if there is resistance in the alternator wiring.Â  That resi!

 Â stance could result in lower system voltage even though the alternator is putting out 14+ volts.

 

 --------

 Joe Gores



	




I think we need to be careful about which kind of alternator we're talking about. IIRC, the post was about an internally regulated ("one wire") alternator. Some older versions require the 'I' terminal to see system voltage for the alternator to start. Some of *that* subgroup will continue operation only with voltage on the 'I' terminal; some will not.Â 

But all of the internally regulated alts I've seen need some form of external overvoltage protection (typically a series contactor in the B lead circuit) which implies the ability to control the alt's ability to feed the system. If the contactor control is 'downstream' of the master switch, you get the one-operation shutdown of the system

If the engine is electrically dependent, which is becoming more and more common, even with traditional a/c engines (automotive style ignition & injection), then something more complicated is needed, to be sure the engine electron source can be controlled independently from the airframe.Â 

Charlie

JohnInReno

Joined: 08 Sep 2007
Posts: 150

Posted: Thu Jul 07, 2016 5:38 am Post subject: Dead battery

Thanks Bob and Joe.



I will dive into the alternator wiring on this plane. I see a "page per 

system" in the future.



john



On 7/7/2016 5:24 AM, user9253 wrote:

 	  Quote: 	
		   



 Just to emphasize what Bob said, connecting the alternator control wire directly to the "B" terminal is not recommended.  The master switch no longer has control over the electrical system.  It is not a master switch in this case, but is a battery switch.  Shutting off the master switch in flight only disconnects the battery, but does not shut off the electrical system.  Everything will keep working.  If the electrical system needs to be shut off in an emergency like smoke in the cockpit or a fuel leak or high voltage, the only way to accomplish that is to shut off the engine also.  The master switch needs to be placarded, "Inoperative in flight".  The solution is to run the alternator control wire to a panel mounted fused switch.  Doing that will not only eliminate the above problems, but also allow the voltage regulator to monitor actual system voltage instead of alternator output voltage.  They could be different if there is resistance in the alternator wiring.  That resi!

   stance could result in lower system voltage even though the alternator is putting out 14+ volts.



 --------

 Joe Gores





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=457845#457845

_________________
John Morgensen
RV-9A - Born on July 3, 2013
RV4 - for sale

rnjcurtis(at)charter.net
Guest

Posted: Thu Jul 07, 2016 7:49 am Post subject: Dead battery

But all of the internally regulated alts I've seen need some form of external overvoltage protection (typically a series contactor in the B lead circuit) which implies the ability to control the alt's ability to feed the system. If the contactor control is 'downstream' of the master switch, you get the one-operation shutdown of the system



 





Â Â Â Â Â Â Â Â Â Â  I seem to recall a couple of years ago, Bob N. was working on a system 

Â Â Â Â Â Â Â Â Â Â  to safely shut down an internally regulated alternator, and a simple series 

Â Â Â Â Â Â Â Â Â Â  contactor was not the answer.Â  

 

Â Â Â Â Â Â Â Â Â Â  IIRC he never came up with a good recommendation for a circuit and 

Â Â Â Â Â Â Â Â Â Â  procedure to do this.Â  Am I correct or did I miss the final answer???

 

Â Â Â Â Â Â Â Â Â Â  Roger

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Jul 07, 2016 9:22 am Post subject: Dead battery

At 10:48 AM 7/7/2016, you wrote:

  	  Quote: 	
		   

  

  

 But all of the internally regulated alts I've seen need some form of external overvoltage protection (typically a series contactor in the B lead circuit) which implies the ability to control the alt's ability to feed the system. If the contactor control is 'downstream' of the master switch, you get the one-operation shutdown of the system

  

   I seem to recall a couple of years ago, Bob N. was working on a system 

   to safely shut down an internally regulated alternator, and a simple series 

   contactor was not the answer.Â  

  

   IIRC he never came up with a good recommendation for a circuit and 

   procedure to do this.Â  Am I correct or did I miss the final answer???

 	


   Yes, that idea was predicated on a bit of kerfuffle

   over some Van's alternators that eppeared to have

   gone belly up after having been switched on/off

   using the Figure Z-24 ov manager.



   To the best of my knowledge there was no failure

   analysis conducted on the damaged units. The

   general consensus amongst the best-guessers

   was that the alternators were switched under

   load . . . perhaps at rpms more than idle and

   the subsequent load-dump (automotive parlance 

   load-dump) zapped the alternators.



   Nobody knew the pedigree of Van's offerings.

   Further, my visit to MPCA overhaul operations

   in San Diego/Tijuana demonstrated that a

   righteous/capable overhauler produces parts

   immune to such events (see chapter on alternators

   in the 'Connection).



   The more sophisticated controller was not 

   pursued as probably unnecessary.  Even if

   the alternator is not so capably remanufactured,

   turning it on/off under load and running faster

   than idle is simply not necessary. Hence, Z-24

   has not be replaced or updated.



 



 

   Bob . . .

JohnInReno

Joined: 08 Sep 2007
Posts: 150

Posted: Thu Jul 07, 2016 10:24 am Post subject: Dead battery

A quick test reveals that you are absolutely right. The master switch is 

"Inoperative in flight" as long as the engine is running.



I am considering running the control wire through a panel mounted 

pullable breaker as a temporary solution.

On 7/7/2016 5:24 AM, user9253 wrote:

 	  Quote: 	
		   



 Just to emphasize what Bob said, connecting the alternator control wire directly to the "B" terminal is not recommended.  The master switch no longer has control over the electrical system.  It is not a master switch in this case, but is a battery switch.  Shutting off the master switch in flight only disconnects the battery, but does not shut off the electrical system.  Everything will keep working.  If the electrical system needs to be shut off in an emergency like smoke in the cockpit or a fuel leak or high voltage, the only way to accomplish that is to shut off the engine also.  The master switch needs to be placarded, "Inoperative in flight".  The solution is to run the alternator control wire to a panel mounted fused switch.  Doing that will not only eliminate the above problems, but also allow the voltage regulator to monitor actual system voltage instead of alternator output voltage.  They could be different if there is resistance in the alternator wiring.  That resi!

   stance could result in lower system voltage even though the alternator is putting out 14+ volts.



 --------

 Joe Gores





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=457845#457845

_________________
John Morgensen
RV-9A - Born on July 3, 2013
RV4 - for sale

JOHN TIPTON

Joined: 17 Sep 2006
Posts: 239
Location: Torquay - England

Posted: Thu Jul 07, 2016 11:44 am Post subject: Dead battery

Roger

So you saying that the Plane-power alternators (as fitted to many RVs) need external over voltage protection

http://www.plane-power.com/pdf/internally%20regulated%20experimental%20alternator%20information.pdf

John



Sent from my iPad



     ----x--O--x----

On 7 Jul 2016, at 04:48 pm, Roger <rnjcurtis(at)charter.net (rnjcurtis(at)charter.net)> wrote:

 	  Quote: 	
		  

 

 

 



But all of the internally regulated alts I've seen need some form of external overvoltage protection (typically a series contactor in the B lead circuit) which implies the ability to control the alt's ability to feed the system. If the contactor control is 'downstream' of the master switch, you get the one-operation shutdown of the system



 





           I seem to recall a couple of years ago, Bob N. was working on a system 

           to safely shut down an internally regulated alternator, and a simple series 

           contactor was not the answer.  

 

           IIRC he never came up with a good recommendation for a circuit and 

           procedure to do this.  Am I correct or did I miss the final answer???

 

           Roger

   =================================== st">http://www.matronics.com/Navigator?AeroElectric-List =================================== cs.com =================================== om =================================== matronics.com/contribution ===================================

ceengland7(at)gmail.com
Guest

Posted: Thu Jul 07, 2016 11:53 am Post subject: Dead battery

John,



Which alternator style are you using? If it's internally regulated, let 

us know what happens after you install the switch in the 'I' lead. Some 

alternators won't start without 12V on the 'I' lead, but will continue 

to operate after breaking the 'I' lead connection. Regardless, you still 

need positive control over the alternator if it has a regulator 'failed 

hot' overvoltage type of failure, and opening the 'I' lead is unlikely 

to offer positive protection. (Shorted components in the internal 

regulator can keep the alternator 'hot' no matter what you do to control 

terminals.)



Charlie



On 7/7/2016 1:21 PM, John Morgensen wrote:

 	  Quote: 	
		   

 <john(at)morgensen.com>



 A quick test reveals that you are absolutely right. The master switch 

 is "Inoperative in flight" as long as the engine is running.



 I am considering running the control wire through a panel mounted 

 pullable breaker as a temporary solution.

 On 7/7/2016 5:24 AM, user9253 wrote:

> 

>

> Just to emphasize what Bob said, connecting the alternator control 

> wire directly to the "B" terminal is not recommended. The master 

> switch no longer has control over the electrical system.  It is not a 

> master switch in this case, but is a battery switch.  Shutting off 

> the master switch in flight only disconnects the battery, but does 

> not shut off the electrical system.  Everything will keep working.  

> If the electrical system needs to be shut off in an emergency like 

> smoke in the cockpit or a fuel leak or high voltage, the only way to 

> accomplish that is to shut off the engine also.  The master switch 

> needs to be placarded, "Inoperative in flight".  The solution is to 

> run the alternator control wire to a panel mounted fused switch.  

> Doing that will not only eliminate the above problems, but also allow 

> the voltage regulator to monitor actual system voltage instead of 

> alternator output voltage.  They could be different if there is 

> resistance in the alternator wiring.  That re!

 si!

>   stance could result in lower system voltage even though the 

> alternator is putting out 14+ volts.

>

> --------

> Joe Gores

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