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Voltage drop

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Laz

Joined: 04 Jan 2016
Posts: 30

Posted: Sat Aug 20, 2016 6:39 am Post subject: Voltage drop

I was doing some checks on my RV8 electrical system that I just finished a few weeks ago. This is a brand new plane under construction. Before I fired up any of the Garmin G3x stuff, I tested the usual systems , starter , fuel pump lights etc. all seemed to work fine. I fired up the G3x and it also come on line with no problems.



Yesterday I had everything on line and tested the starter again. When the starter turned all my other electronics died. As soon as the starter stopped they came back on. It appears that the current draw from the starter took the voltage available to the other Items so low they shut down ( most of the G3X stuff shuts down below 11 volts or so). I have a new odyssey battery 680 and it appears to be charged. Here are my questions.



1. Battery solenoid gets warm with the battery master on. Is this normal? 



2. Could this be a battery issue?



3. What test can I perform on the solenoid, battery etc. ?



Thanks

user9253

Joined: 28 Mar 2008
Posts: 1921
Location: Riley TWP Michigan

Posted: Sat Aug 20, 2016 7:46 am Post subject: Re: Voltage drop

Everything that you described sounds normal to me. Check out Bob's Z-10/8 electrical drawing with a brownout battery.

_________________
Joe Gores

Dave Saylor

Joined: 11 Jan 2015
Posts: 209
Location: GILROY, CA

Posted: Sat Aug 20, 2016 8:11 am Post subject: Voltage drop

The contactor normally gets a little warm--no worries there.Â 



Your battery is probably just fine. My 925 doesÂ the same thing.Â 

You'll need some kind of back-up battery to prevent what you're describing. I use one from TCW that works great.

--Dave





On Saturday, August 20, 2016, Michael Lazarowicz <tllaz330(at)gmail.com (tllaz330(at)gmail.com)> wrote:

 	  Quote: 	
		  I was doing some checks on my RV8 electrical system that I just finished a few weeks ago. This is a brand new plane under construction. Before I fired up any of the Garmin G3x stuff, I tested the usual systems , starter , fuel pump lights etc. all seemed to work fine. I fired up the G3x and it also come on line with no problems.



Yesterday I had everything on line and tested the starter again. When the starter turned all my other electronics died. As soon as the starter stopped they came back on. It appears that the current draw from the starter took the voltage available to the other Items so low they shut down ( most of the G3X stuff shuts down below 11 volts or so). I have a new odyssey battery 680 and it appears to be charged. Here are my questions.



1. Battery solenoid gets warm with the battery master on. Is this normal? 



2. Could this be a battery issue?



3. What test can I perform on the solenoid, battery etc. ?



Thanks

_________________
--Dave
KWVI

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Aug 20, 2016 3:16 pm Post subject: Voltage drop

 	  Quote: 	
		  

 Yesterday I had everything on line and tested the starter again. When the starter turned all my other electronics died. As soon as the starter stopped they came back on. It appears that the current draw from the starter took the voltage available to the other Items so low they shut down ( most of the G3X stuff shuts down below 11 volts or so). I have a new odyssey battery 680 and it appears to be charged. 	




  What engine, alternator and battery combination?



  	  Quote: 	
		  Here are my questions. 	


  Your battery is either (1) not charged -OR- (2) too small -OR-

  Both.



 

  	  Quote: 	
		  1. Battery solenoid gets warm with the battery master on. Is this normal? 	


  Yes



 

  	  Quote: 	
		  2. Could this be a battery issue? 	


   Probably . . .



 

  	  Quote: 	
		  3. What test can I perform on the solenoid, battery etc. ? 	


   Put a computer controlled charger on the battery

   and leave it connected until the charger says, "it's

   charged.



   Fire up the engine and report back on

   your observations . . . in particular, what

   is the bus voltage with the engine running,

   alternator ON, normal running loads ON.

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Aug 20, 2016 3:33 pm Post subject: Voltage drop

At 11:10 AM 8/20/2016, you wrote:

  	  Quote: 	
		  The contactor normally gets a little warm--no worries there.Â 



 Your battery is probably just fine. My 925 doesÂ the same thing.Â 



 You'll need some kind of back-up battery to prevent what you're describing. I use one from TCW that works great. 	


   Oops . . . I stubbed my toe here. If you have any

   electro-whizzies that reboot when presented with

   a bus voltage below 11.0 volts . . . then they almost

   certainly will reboot every time you start the engine.



   I'm somewhat chagrined that folks who build and qualify

   these panel mounted super-computers don't either (1)

   study the real world of bus voltage behaviors during

   engine start and/or (2) advise the customer that their

   product WILL reboot during a start-up transient that

   has ALWAYS existed on EVERY airplane.



   To my mind, the simplest work-around is simply not to turn

   on . . . or depend on these gizmos until after engine start.

   Yeah, I know, our instructors taught us to concentrate on

   the oil pressure display after engine start with a finger

   on the mag switches lest the pressure not come up as expected.



   But I would be interested to hear if anyone on this list

   has ever experienced an failure of oil circulation that did

   not manifest until right after start up. No doubt, Lindbergh

   and contemporaries had good reason to worry about such things.

   Those guys carried tool boxes around in the rear cockpit

   with an eye toward needing off field maintenance of one

   kind or another.



   Now we have a new suite of technology which, for reasons

   we'll never know, was NOT designed to replace

   legacy instrumentation. DO-160 requires a qualified

   product to (1) not be damaged by and (2) recover gracefully

   from bus voltage brownouts quantified in the test

   requirements document.



   Problem is, graceful recovery has not been interpreted

   to mean that the oil pressure display on the glass screen

   needs to be as available and responsive as their steam

   gage counterparts during the first few seconds after engine

   start.



   This leaves the system integrator (YOU) with a problem.

   If you're going to pay homage to the legacy philosophy

   for monitoring engine parameters that were of intense interest

   to Charles Lindbergh, then we have to ADD power supply

   brown-out buffers for these new electro-whizzies . . . that

   COULD have been designed to accommodate such brown-outs.



   The question becomes, are we adding cost, weight and complexity

   to a system striving to honor a operating practice that

   has been around since Lindbergh? What are the demonstrated

   risks for cranking up an engine 'blind' an waiting for

   the 'new' technology to wake up and report for duty?    



 

   Bob . . .

Kellym

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

Posted: Sat Aug 20, 2016 4:03 pm Post subject: Voltage drop

The only situation I have experienced where oil pressure response time 

was important is for a cold start, as in below freezing, where the 

amount of pre-heat is questionable as to whether it was applied long 

enough. As in if pressure doesn't come up in 30 seconds, one should shut 

down and apply heat longer to the engine compartment. Seems like some 

electrowhizzy engine monitors take 30 seconds to boot. On the other 

hand, most of them respond well to a small backup battery that keeps 

input voltage high enough to prevent a reboot.



On 8/20/2016 4:06 PM, Robert L. Nuckolls, III wrote:

     To my mind, the simplest work-around is simply not to turn

 	  Quote: 	
		     on . . . or depend on these gizmos until after engine start.

   Yeah, I know, our instructors taught us to concentrate on

   the oil pressure display after engine start with a finger

   on the mag switches lest the pressure not come up as expected.




	


 	  Quote: 	
		     Now we have a new suite of technology which, for reasons

   we'll never know, was NOT designed to replace

   legacy instrumentation. DO-160 requires a qualified

   product to (1) not be damaged by and (2) recover gracefully

   from bus voltage brownouts quantified in the test

   requirements document.


	


 	  Quote: 	
		     The question becomes, are we adding cost, weight and complexity

   to a system striving to honor a operating practice that

   has been around since Lindbergh? What are the demonstrated

   risks for cranking up an engine 'blind' an waiting for

   the 'new' technology to wake up and report for duty?



   Bob . . .

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

theidtke(at)cox.net
Guest

Posted: Sat Aug 20, 2016 4:09 pm Post subject: Voltage drop

Fairly common occurrence with the new electronic panels.  

Did a fair amount of research on this before deciding to feed at least one glass panel with an alternate battery so that in addition to not being affected by startup (having immediate engine instrumentation awareness when I do), tasks like doing flight plans can be done with the engine off.

Just a thought

Anyway, Bob has a few 2 battery diagrams in his book that were extremely helpful when I did my panel/avionics/engine monitoring system. 

Trent

 

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L. Nuckolls, III

Sent: Saturday, August 20, 2016 4:07 PM

To: aeroelectric-list(at)matronics.com

Subject: Re: Voltage drop

 

At 11:10 AM 8/20/2016, you wrote:

The contactor normally gets a little warm--no worries there.Â 



Your battery is probably just fine. My 925 doesÂ the same thing.Â 



You'll need some kind of back-up battery to prevent what you're describing. I use one from TCW that works great.



  Oops . . . I stubbed my toe here. If you have any

  electro-whizzies that reboot when presented with

  a bus voltage below 11.0 volts . . . then they almost

  certainly will reboot every time you start the engine.



  I'm somewhat chagrined that folks who build and qualify

  these panel mounted super-computers don't either (1)

  study the real world of bus voltage behaviors during

  engine start and/or (2) advise the customer that their

  product WILL reboot during a start-up transient that

  has ALWAYS existed on EVERY airplane.



  To my mind, the simplest work-around is simply not to turn

  on . . . or depend on these gizmos until after engine start.

  Yeah, I know, our instructors taught us to concentrate on

  the oil pressure display after engine start with a finger

  on the mag switches lest the pressure not come up as expected.



  But I would be interested to hear if anyone on this list

  has ever experienced an failure of oil circulation that did

  not manifest until right after start up. No doubt, Lindbergh

  and contemporaries had good reason to worry about such things.

  Those guys carried tool boxes around in the rear cockpit

  with an eye toward needing off field maintenance of one

  kind or another.



  Now we have a new suite of technology which, for reasons

  we'll never know, was NOT designed to replace

  legacy instrumentation. DO-160 requires a qualified

  product to (1) not be damaged by and (2) recover gracefully

  from bus voltage brownouts quantified in the test

  requirements document.



  Problem is, graceful recovery has not been interpreted

  to mean that the oil pressure display on the glass screen

  needs to be as available and responsive as their steam

  gage counterparts during the first few seconds after engine

  start.



  This leaves the system integrator (YOU) with a problem.

  If you're going to pay homage to the legacy philosophy

  for monitoring engine parameters that were of intense interest

  to Charles Lindbergh, then we have to ADD power supply

  brown-out buffers for these new electro-whizzies . . . that

  COULD have been designed to accommodate such brown-outs.



  The question becomes, are we adding cost, weight and complexity

  to a system striving to honor a operating practice that

  has been around since Lindbergh? What are the demonstrated

  risks for cranking up an engine 'blind' an waiting for

  the 'new' technology to wake up and report for duty?    



  Bob . . .

Laz

Joined: 04 Jan 2016
Posts: 30

Posted: Sat Aug 20, 2016 5:59 pm Post subject: Voltage drop

Thanks Bob,



I do have a backup battery that is already wired in but have it

disconnected because there is no charging going on.  The other problem is

that my odyssey battery (680) was more discharged than I thought .  It is

on a charger now and it should rectify the problem.  I was just concerned I

had a bad relay or miss-wired something.  The good news is I checked all my

wiring Battery/ Alt. switch etc.  They were all fine.



I do have a basic question that I cannot seem to answer in my mind.  When

the Battery switch is on, there is power going to the alternator via the

main B lead. Since that lead is connected directly to the output side of

the battery relay dose it not draw a significant amount of current when the

Battery master is on and the alternator is not running.  In you book it

show hat  lead connected to coils that are stationary in the alternator,

then to ground believe.  My non electrical mind just cannot figure that out

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Aug 21, 2016 6:03 am Post subject: Voltage drop

At 06:59 PM 8/20/2016, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: Kelly McMullen <kellym(at)aviating.com>



 The only situation I have experienced where oil pressure response time was important is for a cold start, as in below freezing, where the amount of pre-heat is questionable as to whether it was applied long enough. As in if pressure doesn't come up in 30 seconds, one should shut down and apply heat longer to the engine compartment. Seems like some electrowhizzy engine monitors take 30 seconds to boot. On the other hand, most of them respond well to a small backup battery that keeps input voltage high enough to prevent a reboot. 	


   Yeah. I recall getting ready to depart

   Kansas City one morning when the airplane

   had sat out in -10F weather. We heated the

   engine and used ground power to supplement

   a cold battery. Engine started readily

   but the oil pressure didn't really start to

   move for a really long time (didn't have the stop

   watch out). The oil pressure gage was connected

   to the engine through a small bore copper line.

   Oil in that line behind the fire wall did not

   get warmed in pre-heat . . . and was essentially

   the consistency of peanut butter.



   Under some circumstances, even the legacy

   steam gage can take some time to offer useful

   information.



 

 

   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Aug 21, 2016 7:49 am Post subject: Voltage drop

Posted this eariler and got a bounce from the

 ListServer about having exceeded attachment

 limits. Need to look into that.



 In the mean time, here's a repost with links

 to images:



 



 At 08:57 PM 8/20/2016, you wrote:

  	  Quote: 	
		  Thanks Bob,



 I do have a backup battery that is already wired in but have it disconnected because there is no charging going on. 	


   Don't understand this . . . is this a system

   battery that is part of your airplane's architecture

   or is it associated with a specific appliance

   as part of its design?



  	  Quote: 	
		  Â  The other problem is that my odyssey battery (680) was more discharged than I thought .Â  It is on a charger now and it should rectify the problem. I was just concerned I had a bad relay or miss-wired something.Â  The good news is I checked all my wiring Battery/ Alt. switch etc.Â  They were all fine. 	


    . . . good connecting of the dots . . .



 

  	  Quote: 	
		  I do have a basic question that I cannot seem to answer in my mind.Â  When the Battery switch is on, there is power going to the alternator via the main B lead. Since that lead is connected directly to the output side of the battery relay dose it not draw a significant amount of current when the Battery master is on and the alternator is not running.Â  In you book it show hatÂ  lead connected to coils that are stationary in the alternator, then to ground believe.Â  My non electrical mind just cannot figure that out. 	


   An alternator generally has two connections

   to the ship's electrical system. (1) The "B-Lead"

   or battery lead that is a power-output connection

   and an input lead that is (2a) excitation from the

   regulator to the field . . . 



  http://www.aeroelectric.com/List_Files/Externally_Regulated-s.jpg



  . . . or (2b) on/off control to the internal

  regulator.



  http://www.aeroelectric.com/List_Files/Internally_Regulated-s.jpg



   In both cases, you can see that the B-lead

   connects to the + side of a three-phase

   rectifier . . . diodes that convert the

   internally generated AC into DC while

   preventing any back flow of current from

   the battery into the alternator.



   In all automotive applications, you will find that

   the b-lead is always connected to the vehicle's

   battery. The factory stock (+) battery cable for

   my truck comes with two wires, a fat wire to the

   starter solenoid and a not-so-fat wire running

   directly to the alternator b-lead - power never

   flows into this lead as long as the diodes

   are intact.



   The only 'input' lead to an externally regulated

   alternator draws current when the alternator

   control switch is ON. This is field current

   from the regulator attempting to control

   bus voltage. If the engine is not yet running,

   the regulator will 'full field' the alternator

   causing as much as 3 amps of draw on the

   battery.



   The modern internally regulated alternator

   often features an integrated circuit that

   'watches' for the presence of ac voltage

   from the stator windings. If no AC present

   then the alternator is not rotating . . . and

   field current is shut off. This prevents

   the otherwise inevitable, non-productive

   drain during times the engine is not running.



 

  	  Quote: 	
		  It's been 5 years since I retired, but I do remember some screen interruption, all be it small and fast during engine starts on some if not all the planes I flew to make a buck.Â  Usually when changing from 

 APU power to the engine driven generators. Â  I guess its just part of the program 	


   Correct. This is a function of time-to-boot-up

   inherent in the design of the appliance.

   As I recall, all of the screens in the

   line of Beech products pretty much came

   alive in a second or less after application

   of operating power whether first-on or

   post brown-out . . . so we KNOW it can

   be done. All of my software driven products

   are wide-eyed, bright-eyed and bushy-tailed

   milliseconds after power up.



   But ever since the Blue Mountain days of

   EFIS products offered to owner built and

   maintained aircraft, there have be a variety

   of instances where boot-up times were sometimes

   distressingly long (Blue Mountain had a HARD

   DRIVE!!). So not only did that product

   need to load an operating system, it might

   take many seconds after the software woke

   up until the analog rate integration

   calculations could get stood up in deducing

   the gravity vector.



   We've come a long way baby . . . but it's

   still disappointing that some of the big

   guns in the electronic instrumentation

   business for light aircraft are not not

   implementing the best we know how to do

   in managing power-up/brown-outs events.



 

   Bob . . . 



  

 

   Bob . . .

ashleysc(at)broadstripe.n
Guest

Posted: Sun Aug 21, 2016 8:19 am Post subject: Voltage drop

Hi Bob;



 Neat and very understandable schematics for externally and internally regulated alternators. Would you care to provide one for a internally regulated, permanent magnet alternator, so as to cover the subject exhaustively? I think I can deduce same, but would feel better to have it "from the horse's mouth."

 Cheers!   Stu.

 



   From: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com>

To: aeroelectric-list(at)matronics.com

Sent: Sunday, August 21, 2016 7:57:50 AM

Subject: Re: Voltage drop

 



Posted this eariler and got a bounce from the

ListServer about having exceeded attachment

limits. Need to look into that.

 



In the mean time, here's a repost with links

to images:

 

 



At 08:57 PM 8/20/2016, you wrote:

  	  Quote: 	
		  Thanks Bob,

 



I do have a backup battery that is already wired in but have it disconnected because there is no charging going on. 	


  Don't understand this . . . is this a system

  battery that is part of your airplane's architecture

  or is it associated with a specific appliance

  as part of its design?

 



  	  Quote: 	
		  Ã‚  The other problem is that my odyssey battery (680) was more discharged than I thought .Ã‚  It is on a charger now and it should rectify the problem. I was just concerned I had a bad relay or miss-wired something.Ã‚  The good news is I checked all my wiring Battery/ Alt. switch etc.Ã‚  They were all fine. 	


   . . . good connecting of the dots . . .

 

  	  Quote: 	
		  I do have a basic question that I cannot seem to answer in my mind.Ã‚  When the Battery switch is on, there is power going to the alternator via the main B lead. Since that lead is connected directly to the output side of the battery relay dose it not draw a significant amount of current when the Battery master is on and the alternator is not running.Ã‚  In you book it show hatÃ‚  lead connected to coils that are stationary in the alternator, then to ground believe.Ã‚  My non electrical mind just cannot figure that out. 	


  An alternator generally has two connections

  to the ship's electrical system. (1) The "B-Lead"

  or battery lead that is a power-output connection

  and an input lead that is (2a) excitation from the

  regulator to the field . . . 

 



http://www.aeroelectric.com/List_Files/Externally_Regulated-s.jpg

 



 . . . or (2b) on/off control to the internal

 regulator.

 



http://www.aeroelectric.com/List_Files/Internally_Regulated-s.jpg

 



  In both cases, you can see that the B-lead

  connects to the + side of a three-phase

  rectifier . . . diodes that convert the

  internally generated AC into DC while

  preventing any back flow of current from

  the battery into the alternator.

 



  In all automotive applications, you will find that

  the b-lead is always connected to the vehicle's

  battery. The factory stock (+) battery cable for

  my truck comes with two wires, a fat wire to the

  starter solenoid and a not-so-fat wire running

  directly to the alternator b-lead - power never

  flows into this lead as long as the diodes

  are intact.

 



  The only 'input' lead to an externally regulated

  alternator draws current when the alternator

  control switch is ON. This is field current

  from the regulator attempting to control

  bus voltage. If the engine is not yet running,

  the regulator will 'full field' the alternator

  causing as much as 3 amps of draw on the

  battery.

 



  The modern internally regulated alternator

  often features an integrated circuit that

  'watches' for the presence of ac voltage

  from the stator windings. If no AC present

  then the alternator is not rotating . . . and

  field current is shut off. This prevents

  the otherwise inevitable, non-productive

  drain during times the engine is not running.

 

  	  Quote: 	
		  It's been 5 years since I retired, but I do remember some screen interruption, all be it small and fast during engine starts on some if not all the planes I flew to make a buck.Ã‚  Usually when changing from 

APU power to the engine driven generators. Ã‚  I guess its just part of the program 	


  Correct. This is a function of time-to-boot-up

  inherent in the design of the appliance.

  As I recall, all of the screens in the

  line of Beech products pretty much came

  alive in a second or less after application

  of operating power whether first-on or

  post brown-out . . . so we KNOW it can

  be done. All of my software driven products

  are wide-eyed, bright-eyed and bushy-tailed

  milliseconds after power up.

 



  But ever since the Blue Mountain days of

  EFIS products offered to owner built and

  maintained aircraft, there have be a variety

  of instances where boot-up times were sometimes

  distressingly long (Blue Mountain had a HARD

  DRIVE!!). So not only did that product

  need to load an operating system, it might

  take many seconds after the software woke

  up until the analog rate integration

  calculations could get stood up in deducing

  the gravity vector.

 



  We've come a long way baby . . . but it's

  still disappointing that some of the big

  guns in the electronic instrumentation

  business for light aircraft are not not

  implementing the best we know how to do

  in managing power-up/brown-outs events.

 



 

  Bob . . . 

 



  Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Aug 21, 2016 11:09 am Post subject: Voltage drop

At 11:18 AM 8/21/2016, you wrote:

  	  Quote: 	
		  Hi Bob;

 Neat and very understandable schematics for externally and internally regulated alternators. Would you care to provide one for a internally regulated, permanent magnet alternator, so as to cover the subject exhaustively? I think I can deduce same, but would feel better to have it "from the horse's mouth."

 Cheers!   Stu. 	


    I'm not sure such a critter exitsts.

    The only PM alternators I'm aware

    of are exceedingly simple arrays of

    magnets rotated about a stator winding

    of suitable wire. Check out the images

    at . . .



  http://tinyurl.com/z27kpv4



    These are PM alternators characteristic

    of all such products from the lowly SD-8 up

    through the 30A, 3-phase machines on some

    small tractors.



    Spinning magnets, stationary wires.



    The energy coming out of these machines is

    an AC current with frequency and voltage

    proportional to engine RPM.



    This is why the 'regulators' paired with

    these devices are more properly called

    RECTIFIER-REGULATORS.



    They must not only convert the AC to DC

    (like the diodes in the wound field

    alternators) they must CONTROL that voltage

    through devices that must CARRY the full

    load current. Hence, there are no nifty,

    itty-bitty regulators like those found in

    wound field machines . . . instead, the R-R

    is a rather robust device obviously designed

    to dissipate HEAT.



    It's a whole other breed of cat . . . so

    sayeth the north end of the northbound

    horse.                 



 



 

   Bob . . .

cbirdsall6(at)cox.net
Guest

Posted: Sun Aug 21, 2016 12:27 pm Post subject: Voltage drop

Bob, 

With respect to your 4th paragraph - I work in the TC maintenance side of the aviation industry, and have seen oil delivery system failure manifest itself first during engine start.  The majority of those times the failure was either maintenance-induced or were on aircraft that have sat for extended periods with no attempt to pre-oil before starting (one of the bigger offenders in the latter in my experience has been geared, turbocharged Continentals in Cessna 400 series aircraft, for some reason). A few, however were mechanical failures that were clued-in by oil pressure goofiness.

One of those involved a pipeline patrol aircraft whose operator said that he didn't think the engine was developing full power. He also mentioned casually that the oil pressure was jumping up high right away after engine start, and had been doing that for several flights. That little tidbit led us to the oil filter, which was chock full o metal bits. (After further clue-taking the engine was replaced...)

My take on this is that oil pressure behavior is one of several clues to engine health. If the behavior departs from the norm then it's time to start asking why. It's also the last chance you get to discover that after draining the oil for an oil change, you forgot to put oil back in - before it gets turned into very expensive paper weights.  It's why I'd recommend having some sort of backup for use during engine start or other times when the electrical system has failed.  In the TC world that's usually a backup battery (a la G1000), but even a simple idiot light attached to an oil pressure switch would help.



Chuck



On Aug 20, 2016, at 6:06 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

  At 11:10 AM 8/20/2016, you wrote:

  	  Quote: 	
		  The contactor normally gets a little warm--no worries there.Ã‚ 



 Your battery is probably just fine. My 925 doesÃ‚ the same thing.Ã‚ 



 You'll need some kind of back-up battery to prevent what you're describing. I use one from TCW that works great. 	


   Oops . . . I stubbed my toe here. If you have any

   electro-whizzies that reboot when presented with

   a bus voltage below 11.0 volts . . . then they almost

   certainly will reboot every time you start the engine.



   I'm somewhat chagrined that folks who build and qualify

   these panel mounted super-computers don't either (1)

   study the real world of bus voltage behaviors during

   engine start and/or (2) advise the customer that their

   product WILL reboot during a start-up transient that

   has ALWAYS existed on EVERY airplane.



   To my mind, the simplest work-around is simply not to turn

   on . . . or depend on these gizmos until after engine start.

   Yeah, I know, our instructors taught us to concentrate on

   the oil pressure display after engine start with a finger

   on the mag switches lest the pressure not come up as expected.



   But I would be interested to hear if anyone on this list

   has ever experienced an failure of oil circulation that did

   not manifest until right after start up. No doubt, Lindbergh

   and contemporaries had good reason to worry about such things.

   Those guys carried tool boxes around in the rear cockpit

   with an eye toward needing off field maintenance of one

   kind or another.



   Now we have a new suite of technology which, for reasons

   we'll never know, was NOT designed to replace

   legacy instrumentation. DO-160 requires a qualified

   product to (1) not be damaged by and (2) recover gracefully

   from bus voltage brownouts quantified in the test

   requirements document.



   Problem is, graceful recovery has not been interpreted

   to mean that the oil pressure display on the glass screen

   needs to be as available and responsive as their steam

   gage counterparts during the first few seconds after engine

   start.



   This leaves the system integrator (YOU) with a problem.

   If you're going to pay homage to the legacy philosophy

   for monitoring engine parameters that were of intense interest

   to Charles Lindbergh, then we have to ADD power supply

   brown-out buffers for these new electro-whizzies . . . that

   COULD have been designed to accommodate such brown-outs.



   The question becomes, are we adding cost, weight and complexity

   to a system striving to honor a operating practice that

   has been around since Lindbergh? What are the demonstrated

   risks for cranking up an engine 'blind' an waiting for

   the 'new' technology to wake up and report for duty?    



 

   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Aug 21, 2016 4:13 pm Post subject: Voltage drop

At 03:24 PM 8/21/2016, you wrote:

  	  Quote: 	
		  Bob, 



 With respect to your 4th paragraph - I work in the TC maintenance side of the aviation industry, and have seen oil delivery system failure manifest itself first during engine start.  The majority of those times the failure was either maintenance-induced or were on aircraft that have sat for extended periods with no attempt to pre-oil before starting (one of the bigger offenders in the latter in my experience has been geared, turbocharged Continentals in Cessna 400 series aircraft, for some reason). A few, however were mechanical failures that were clued-in by oil pressure goofiness. 	
  Yes, aviation has been plagued with numerous examples of engines that operated on the edge of self destruction . . . the C175 engines come to mind also. But again, what are the probabilities that upon starting an engine predominant in OBAM aviation aircraft that it will present with a loss of oil pressure  . . . given that it taxied an airplane to parking in the not too distant past?



  Further, an aviation maintenance career puts you in situations like doctors . . . who never see anyone but sick people. My last five years at Beech concentrated on a series of seemingly intractable difficulties . . . but for every airplane I touched, there were thousands that did not need or would benefit from my attention.



 	  Quote: 	
		   My take on this is that oil pressure behavior is one of several clues to engine health. If the behavior departs from the norm then it's time to start asking why. It's also the last chance you get to discover that after draining the oil for an oil change, you forgot to put oil back in - before it gets turned into very expensive paper weights. 	
  But do the FMEA on these hypothetical scenarios. It's one thing that a particular engine/airframe combination has a history of difficulties related to loss of oil pressure . . . is anyone here on the List flying such a machine? Forgetting to put the oil in . . . any owner/op at elevated risk for such errors has dozens of opportunities for equal if not or more hazardous examples of absent minded events.



  If anyone is truly concerned about immediate notification of oil pressure after start up, I suggest that an oil pressure switch and warning light would be a simpler, lower cost, lighter weight and nearly zero maintenance solution compared with any sort of battery installation. Such switches are not subject to the effects of brown-out.

 

    Bob . . .

Jim Baker

Joined: 30 Mar 2006
Posts: 181
Location: Sayre, PA

Posted: Sun Aug 21, 2016 5:19 pm Post subject: Voltage drop

Learned to fly a J3 with my Dad as the instructor. Even the old C65 was prone to startup oil pressure issues. Had to watch carefully to see if pressure would develop immediately after the hand prop. If not, you'd have to pull the pressure line off the back of the pump and prime it with a squirt can so the gears would have something to work with.



Jim Baker

405 426 5377



--

ashleysc(at)broadstripe.n
Guest

Posted: Sun Aug 21, 2016 6:16 pm Post subject: Voltage drop

Hi Bob;



 One such critter is DB Electrical APM0009, which is a 12 V., 20 Amp, internally regulated permanent magnet alternator.

 Cheers!   Stu.

 



   From: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com>

To: aeroelectric-list(at)matronics.com

Sent: Sunday, August 21, 2016 11:17:35 AM

Subject: Re: Voltage drop

 



At 11:18 AM 8/21/2016, you wrote:

  	  Quote: 	
		  Hi Bob;

Neat and very understandable schematics for externally and internally regulated alternators. Would you care to provide one for a internally regulated, permanent magnet alternator, so as to cover the subject exhaustively? I think I can deduce same, but would feel better to have it "from the horse's mouth."

Cheers!   Stu. 	


   I'm not sure such a critter exitsts.

   The only PM alternators I'm aware

   of are exceedingly simple arrays of

   magnets rotated about a stator winding

   of suitable wire. Check out the images

   at . . .

 



http://tinyurl.com/z27kpv4

 



   These are PM alternators characteristic

   of all such products from the lowly SD-8 up

   through the 30A, 3-phase machines on some

   small tractors.

 



   Spinning magnets, stationary wires.

 



   The energy coming out of these machines is

   an AC current with frequency and voltage

   proportional to engine RPM.

 



   This is why the 'regulators' paired with

   these devices are more properly called

   RECTIFIER-REGULATORS.

 



   They must not only convert the AC to DC

   (like the diodes in the wound field

   alternators) they must CONTROL that voltage

   through devices that must CARRY the full

   load current. Hence, there are no nifty,

   itty-bitty regulators like those found in

   wound field machines . . . instead, the R-R

   is a rather robust device obviously designed

   to dissipate HEAT.

 



   It's a whole other breed of cat . . . so

   sayeth the north end of the northbound

   horse.                 

 

 



 

  Bob . . .

ceengland7(at)gmail.com
Guest

Posted: Mon Aug 22, 2016 6:32 am Post subject: Voltage drop

On 8/22/2016 7:28 AM, Robert L.       Nuckolls, III wrote:

     

      	  Quote: 	
		         At 09:15 PM 8/21/2016, you wrote:

               	  Quote: 	
		  Hi           Bob;

           One such critter is DB Electrical APM0009, which is a 12 V.,           20 Amp,           internally regulated permanent magnet alternator.

           Cheers!   Stu.

         	
       

         Cool! Thanks for the heads-up! Well, if there's

         one such device, there must be others.

       

       

        The really interesting thing about this amalgam

        of technologies is the relative dearth of heat

        dissipation features for a 20 AMP rating.

       

        There appears to be several devices of this

        style

       

                http://tinyurl.com/jyt7wul

       

        They have Lester numbers which suggests that

        the parts are manufactured in large quantities

        for the industrial/automotive world. The

        Arrowhead brand is a new one too . . . pretty

        big outfit.

       

                http://tinyurl.com/hthwy29

       

        I'm tempted to order one of these things to

        'play' with.

       

       

       

                

             Bob . . .                I think that if you inspect that photo carefully, it's apparent that 

these 'internally regulated' units are basically the original PM 

alternator with the regulator bolted to the back. More convenient 

packaging, perhaps, but not really different from bolting an older style 

reg to the back of the old style PM alt.

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Aug 22, 2016 7:18 am Post subject: Voltage drop

 	  Quote: 	
		  I think that if you inspect that photo carefully, it's apparent that these 'internally regulated' units are basically the original PM alternator with the regulator bolted to the back. More convenient packaging, perhaps, but not really different from bolting an older style reg to the back of the old style PM alt. 	


  Oh sure . . . but perhaps we're splitting

  hairs . . . the rectifier-regulator is an

  integral component of the assembly . . .



  Had the designers added an all-enclosing

  shroud or cooling plenum on the back, the

  r-r could easily be deemed 'internal'



  I think the most noteworthy features of this

  product are the apparent output (20A) but

  with nothing obvious in the way of aggressive

  cooling. They may have achieved something

  of an energy management ooup here.



 

   Bob . . .

mike(at)vision499.com
Guest

Posted: Mon Aug 22, 2016 8:26 am Post subject: Voltage drop

MGL makes a product called an "AVIOGUARD" that gives you a steady 13.8v 

out with input between 9v and 36v.



On 2016-08-20 16:37, Michael Lazarowicz wrote:

 	  Quote: 	
		   I was doing some checks on my RV8 electrical system that I just

 finished a few weeks ago. This is a brand new plane under

 construction. Before I fired up any of the Garmin G3x stuff, I tested

 the usual systems , starter , fuel pump lights etc. all seemed to work

 fine. I fired up the G3x and it also come on line with no problems.

 

 Yesterday I had everything on line and tested the starter again. When

 the starter turned all my other electronics died. As soon as the

 starter stopped they came back on. It appears that the current draw

 from the starter took the voltage available to the other Items so low

 they shut down ( most of the G3X stuff shuts down below 11 volts or

 so). I have a new odyssey battery 680 and it appears to be charged.

 Here are my questions.

 

 1. Battery solenoid gets warm with the battery master on. Is this

 normal?

 

 2. Could this be a battery issue?

 

 3. What test can I perform on the solenoid, battery etc. ?

 

 Thanks

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