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Ammeter help

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klburris

Joined: 19 Dec 2009
Posts: 18

Posted: Sat Dec 19, 2009 11:25 pm Post subject: Ammeter help

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Folks;  

Looking for some help in locating an ammeter installation kit of some sort, similar to B&C AEC9035-1 (discontinued). Ideally, it would have a current sensor such as a Tamura L08P050D15 (50 amp or a little smaller) with the required signal processing built in and come with an edgewise 50-0-50 (or 30-0-30) analog panel meter. I was surprised there was not something already made up (or at least easier to find) as I would think there would be a market for it. All help greatly appreciated. Thanks in advance.  

<![if !supportEmptyParas]> <![endif]>  

 AUTOTEXTLIST \s "E-mail Signature" <![endif]-->  

-- Keith  

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nuckolls.bob(at)aeroelect
Guest

Posted: Sun Dec 20, 2009 7:33 am Post subject: Ammeter help

At 01:18 AM 12/20/2009, you wrote:

  	  Quote: 	
		   Folks;

 Looking for some help in locating an ammeter installation kit of some sort, similar to B&C AEC9035-1 (discontinued). Ideally, it would have a current sensor such as a Tamura L08P050D15 (50 amp or a little smaller) with the required signal processing built in and come with an edgewise 50-0-50 (or 30-0-30) analog panel meter. I was surprised there was not something already made up (or at least easier to find) as I would think there would be a market for it. All help greatly appreciated. Thanks in advance.

  

 -- Keith

 

 

 

 	
 

   The AEC9035 was a proposed project that never

   made it to the market. Too complex and too expensive

   to build for the value delivered. Battery ammeters

   are of limited utility and require a higher level

   of understanding to be as useful as a simple LV

   warning light and perhaps alternator load-meters.



   In a system that's designed with attention to failure

   mode effects analysis and complimented by (Plans-B

   for critical failures), the ammeter offers no

   useful data for operating the airplane. Its most

   powerful function is as a diagnostics tool.



   Hence, the market is small. We do offer a customized

   kit for the installation of load meters on one

   or dual alternator systems. These use the simple,

   stable, accurate metallic shunts and simple, low

   cost, pivot and jewel, d'Arsonval meters . . . 



 [img]cid:.0[/img]



 See:



  https://matronics.com/aeroelectric/Catalog/AEC/9007/9007.html



   This approach proved the most elegant for ruggedness,

   stability of calibration and cost of ownership when

   the builder desires a panel display of current.



   Bob . . .

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jonlaury

Joined: 06 Nov 2006
Posts: 336

Posted: Sun Dec 20, 2009 12:05 pm Post subject: Ammeter help

Keith,

  

  

 This is a very tidy, versatile unit at an  attractive price. Check out the user manual.

  

 http://www.aircraftdigital.com/DIGITAL_AMMETER.html

   [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Dec 20, 2009 1:04 pm Post subject: Ammeter help

At 02:02 PM 12/20/2009, you wrote:

  	  Quote: 	
		   Keith,

  

  

 This is a very tidy, versatile unit at an attractive price. Check out the user manual.

  

   http://www.aircraftdigital.com/DIGITAL_AMMETER.html 	


   I've seen this (or similar) instruments used

   as a loadmeter. You set it up to read a 100A

   shunt (50mv = 100.0) and then size the shunt

   to the full scale value of alternator. A little

   label over the AMPS nomenclature to read LOAD

   allows the single instrument to be switched to

   multiple systems.



   Bob . . .    [quote][b]

klburris

Joined: 19 Dec 2009
Posts: 18

Posted: Mon Dec 21, 2009 11:25 pm Post subject: Ammeter help

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Folks;  

Thanks to all who replied-all of it useful. However, I need an explanation, most likely from Bob regarding ammeters.  

Bob, I recently purchased rev 12 of the Connection. Page 4-9, last paragraph says:”… [b]A zero center, battery ammeter is the most desirable and should be the first electrical system instrument you install[/b]”.  

Again, on page 7-12, last paragraph, you state: “…[b]if you plan only one electrical system instrument, make it a battery ammete[/b]r.”.   	  Quote: 	
		  <![if !supportEmptyParas]> <![endif]>With the above being in your book and presumably vetted by yourself, I became confused when I read in your response to my original post, the following: “…Battery ammeters are of limited utility…” and again ”… the ammeter offers no useful data for operating the airplane…”<![if !supportEmptyParas]> <![endif]>I need to ask – did I completely misinterpret the book? I have Rev 12, which I am led to believe is the most current (no pun intended), or has your mind changed substantially since 12 was published? If that is the case, would you be willing to expound and elucidate on the subject of the necessity of ammeters in the cockpit? Thanks in advance. 	
  

 AUTOTEXTLIST \s "E-mail Signature" <![endif]-->  

<![if !supportLists]>n      <![endif]>Keith  

<![if !supportLists]>n      <![endif]>PS – The book is great. I did not become aware of it until I attended an EAA SportAir class where it was highly recommended.  

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nuckolls.bob(at)aeroelect
Guest

Posted: Tue Dec 22, 2009 7:01 am Post subject: Ammeter help

At 01:21 AM 12/22/2009, you wrote:

Folks;

Thanks to all who replied-all of it useful. 

However, I need an explanation, most likely from Bob regarding ammeters.

Bob, I recently purchased rev 12 of the 

Connection. Page 4-9, last paragraph says:”… A 

zero center, battery ammeter is the most 

desirable and should be the first electrical system instrument you install”.

Again, on page 7-12, last paragraph, you state: 

“…if you plan only one electrical system 

instrument, make it a battery ammeter.”.



With the above being in your book and presumably 

vetted by yourself, I became confused when I read 

in your response to my original post, the 

following: “…Battery ammeters are of limited 

utility…” and again ”… the ammeter offers no 

useful data for operating the airplane…”



I need to ask – did I completely misinterpret the 

book? I have Rev 12, which I am led to believe is 

the most current (no pun intended), or has your 

mind changed substantially since 12 was 

published? If that is the case, would you be 

willing to expound and elucidate on the subject 

of the necessity of ammeters in the cockpit? Thanks in advance.



       Keith



PS – The book is great. I did not become aware of 

it until I attended an EAA SportAir class where it was highly recommended.

    Aha! You read the book!  I'm pleased that you've

    not only noted this 'disconnect' but that you brought

    it to the attention of the List . . . Oh yes, thank

    you for the kind words. I'm pleased that you found the

    work useful.



    The chapter on instrumentation is one of the oldest

    in the book . . . and is seriously in need of updating.

    An explanation of what I've written (both times)

    is in order.



    Many, many moons ago, folks who where bolting the

    first generators, batteries and rudimentary mobile

    electro-whizzies to cars. They no doubt pondered the

    best way to tell the operator of the automobile that

    things were going well in the production, storage

    and utilization of electrical energy.



    If you had an opportunity to fill one hole on

    the instrument panel with a electrical system

    monitoring instrument in 1915, what would your

    choice be? A voltmeter would be cool. 7 volts

    or more with the engine running and all electro-

    whizzies turned on would be a comforting thing

    to know. But you could still have a soggy

    battery. Hmmmm . . . well, we DO load test the

    battery every time the car is started . . . but

    then, there's not much advance warning of battery

    aging . . .



    Alternatives to voltmeters were ammeters . . .

    simpler, much more rugged than voltmeters, but

    where to install it? As it turns out, placing

    a -0+ ammeter in series with the battery charge/

    discharge line showed promise. If the ammeter

    reads zero, then the battery is 'happy' (or

    everything is turned off!). By 'happy' we mean that

    bus voltage is high enough to keep the battery

    from being discharged . . . and the battery has

    taken on all the charge it can . . . AT THAT

    PARTICULAR bus voltage. Hmmm . . . assuming that

    the regulator's set-point is where it belongs

    then the battery-ammeter's interpretation is

    simple and accurate.



    Now, you not only have a means by which day-to-

    day wellness of the system can be watched,

    you can compare today's ammeter actions after

    engine-start with those you observed a month

    ago . . . oh yeah, you DO take note of such

    things while conducting a 3-page check-list,

    right?



    The battery ammeter was a useful and probably

    the most practical thing you could do for a

    machine that never leaves the ground.



    But I'd bet not one driving citizen in 1000

    understood and could accurately interpret what

    the ammeter was telling them. I recall an

    episode in my teenaged years where my favorite

    mechanic was talking with a customer who just

    drove up to complain that his battery "wasn't

    charging". He had tried many times to explain

    to the man that the battery would 'charge' only

    when it needed to . . . and all other times

    the ammeter should and would read zero.



    So, in the context of my life-experiences

    up to the time I wrote that chapter, yeah,

    the battery ammeter was a pretty informative

    device. Indeed, virtually all single engine

    Cessna's sported this as the only electrical

    system instrument for decades. In fact,

    those-who-know-more-about-airplanes-than-we-do

    have decreed:



FAR 23.1351(d) Instruments. A means must exist to indicate to

appropriate flight crewmembers the electric power system

quantities essential for safe operation.



(1) For normal, utility, and acrobatic category airplanes with direct

current systems, an ammeter that can be switched into each generator feeder

may be used and, if only one generator exists, the ammeter may be in the

battery feeder.



(2) For commuter category airplanes, the essential electric power system

quantities include the voltage and current supplied by each generator.



    Charles Kettering would probably be pleased that

    his ideas from 1912 were adopted as policy by an

    agency of government. Problem is that while battery

    ammeters are capable of displaying some important

    information about electrical system function, they

    have serious drawbacks. (1) the folks looking

    at the instrument need to understand what the readings

    mean based on some 'empathy' with how various components in

    the system are behaving and (2) they're not easily

    implemented in the Z-figures using SHUNTS because

    we'd like NOT to bring alternator b-leads into the

    cockpit if we can avoid it. Furhter, we don't want

    to run starter current through a shunt that is

    trying to resolve readings down 1 or 2 amps on

    a 2" instrument.



    20 years later . . .



    In our collective deliberations as designers,

    fabricators, operators and maintainers of our

    own airplanes we've adopted policy and practice

    that MONITORS battery condition for the purpose of

    meeting design goals for a lot more than 30 minutes

    of battery-only endurance. It's unlikely that

    even the most attentive pilot is able to resolve

    a 20% drop in battery capacity by observing the

    behaviors of a battery ammeter.



    Further, accurate voltmeters are much easier

    to come by compared to Uncle Charles' time. Shucks,

    about everyone with a digital display throws a

    voltmeter in just for grins.  Regulator set-points

    have become much more stable too. So as it turns

    out now, the single most valuable electrical system

    instrumentation today is a simple low voltage warning

    light that says "Hey Zeek! . . . you're in battery-only

    ops. Time to go to plan-B!".



    Assuming your plan-B is well crafted and MAINTAINED,

    you may confidently continue flight to airport of

    intended destination without breaking a sweat.



    This confidence comes with a price of admission.

    You need to understand how all those things in your

    airplane's electrical system work. What demands they

    have for electrical power and what utility they

    offer or comfortable termination of flight. You

    then take it upon yourself to make sure those demands

    are satisfied if and when the alternator quits. Even

    with Z-13/8, you have greater ability or power electro-

    whizzies if the big dog goes to sleep . . .  but it

    is STILL LIMITED.



    The short answer is: The battery ammeter as a single

    display of electrical system functionality can be and

    has been quite useful for nearly 100 years. I

    suggest that present day goals and expectations

    for system performance would raise the eyebrows if

    not elicit guffaws from our brethren who thought

    their 1965 C-182 was the greatest thing on wings.



    So without trashing what generators, flooded batteries,

    venturi powered t/b, and yes . . .  battery ammeters

    offered us in the past . . . I'll suggest it's time to set

    them aside in favor of more efficient and certainly more

    capable recipes for success.



    If your chunk of panel-glass comes with a hall-effect

    sensor, you can certainly count the flow of electrons

    in any wire you wish . . . including a battery cable.

    No matter where you decide to install it, know that

    the readings it offers are useful only if the observer

    understands WHY they say what they do. The same observer

    must be capable of sorting through the permutations that

    resolve a sense of electrical system health. I.e.,

    the ammeter is first a DIAGNOSTIC tool and a second a

    poor warning tool. That little flashing LV WARNING

    light is the elegant tool for flight operations.



    Revision 13 to the book will have a whole new chapter

    on monitoring the health of the electrical system.



    Bob . . .

user9253

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

Posted: Tue Dec 22, 2009 9:48 am Post subject: Re: Ammeter help

Keith,



   The most important electrical instrument is the voltmeter.  If the voltage is above 14, then you know that the alternator is working and that the battery is being charged.  If the voltage is below 14 and is slowly dropping, then the alternator is not working.  Having a voltmeter or other low voltage warning is essential.  An ammeter is optional.



   The location of the current shunt or sensor is a matter of personal preference.  The ammeter that you are considering, 30-0-30, measures current going into or out of the battery.  Current should usually only flow into the battery (above zero indication) except when the engine is off or perhaps when short term heavy loads are turned on, such as motors.  The information provided by this type of ammeter is not very useful because the voltmeter already tells if the battery is being charged or not.



  Another possible location for the current shunt is in the alternator B lead.  Current in the B lead only flows in one direction, so the meter would not have a below-zero scale.  Since the alternator normally supplies current to the aircraft (not the battery), knowing this current is useful because you know that the alternator is working; and you also know how much total current the aircraft is using for charging the battery and operating the electrical equipment.  Once the battery is fully charged, not much current flows into it.  Then the ammeter indicates current being used by other electrical loads.  If the alternator fails, the ammeter will read zero and you will not know how much current the aircraft is draining from the battery.



   A third possible location for the ammeter shunt is in the wire supplying power to the Main Power Distribution Bus.  The meter would not have a below-zero scale.  In this location the ammeter will tell you exactly how much current is being used by your electrical equipment.  You could turn on one device at a time to determine its current consumption.  Wired like this, the ammeter will not tell you if the current is coming from the battery or from the alternator (but the voltmeter will).



It is up to the builder to decide if an ammeter is useful and if so, then where in the circuit to install it.



Joe

_________________
Joe Gores

jonlaury

Joined: 06 Nov 2006
Posts: 336

Posted: Tue Dec 22, 2009 4:58 pm Post subject: Ammeter Help

Keith thanks for bringing this up.

  

 I was going to install an ammeter in my bird until  this subject arose and and I really started thinking about what useful info the  meter would provide.

  

 I'm building an all electric plane and thought it  would be useful to have an ammeter on board to aid in alternator-out conditions.  I intend to conduct battery capacity tests, at my full E-bus  load, between annuals so that, with an ammeter indicating load on the  battery(s), I would have a reasonable idea of my electrical endurance during  alt-out. My first inclination would be to land at the first opportunity. But I  might choose a more convenient airport further away if I knew my battery(s)  would last with a margin.

  

 I suppose that a voltmeter might be more useful  because I know at what voltage critical components become inop. Electronic  ignition will work down to 7 volts, but at a cost in amps.  Ditto electronic fuel injection with an even heavier amp load to drive  injectors. Haven't tested my fuel pumps but I suspect the motor would be an amp  hog as well at low volts.

  

 So with the knowledge of battery ampacity from  semi-annual tests and a knowledge of my full E-bus load, I would have a ballpark  of my electrical endurance during alt-out and the rate at which  the voltmeter was dropping would be a cross check. 

  

 OK! I now think that a voltmeter is more useful for  determining electrical endurance than an ammeter that just tells me my burn  rate, which I already know from system architecture calcs. An ammeter is similar  to a fuel flow meter. Knowing how much fuel you're burning is not particularly  useful without knowing how much fuel you have. If you can see your fuel level,  you can change throttle settings accordingly. Ditto on electricity.

  

 John

   [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Dec 22, 2009 7:50 pm Post subject: Ammeter Help

At 06:50 PM 12/22/2009, you wrote:

  	  Quote: 	
		   Keith thanks for bringing this up.

  

 I was going to install an ammeter in my bird until this subject arose and and I really started thinking about what useful info the meter would provide.

  

 I'm building an all electric plane and thought it would be useful to have an ammeter on board to aid in alternator-out conditions. I intend to conduct battery capacity tests, at my full E-bus load, between annuals so that, with an ammeter indicating load on the battery(s), I would have a reasonable idea of my electrical endurance during alt-out. My first inclination would be to land at the first opportunity. But I might choose a more convenient airport further away if I knew my battery(s) would last with a margin. 	


    Which is the basis for crafting Plan-B. When the

    LV warning light comes on, it seems more useful to

    KNOW in advance what equipment items you plan to

    run. It's equally useful to KNOW in advance that

    the battery was recently determined to contain

    the energy YOU have set down in design goals

    for YOUR plan B . . . of course this would include

    any margins that contribute to your confidence

    levels.

  	  Quote: 	
		   

 I suppose that a voltmeter might be more useful because I know at what voltage critical components become inop. Electronic ignition will work down to 7 volts, but at a cost in amps. Ditto electronic fuel injection with an even heavier amp load to drive injectors. Haven't tested my fuel pumps but I suspect the motor would be an amp hog as well at low volts. 	


   If you have an electrically dependent engine then

   perhaps your plans should include a second alternator

   capable of supporting the engine . . .

  	  Quote: 	
		   

 So with the knowledge of battery ampacity from semi-annual tests and a knowledge of my full E-bus load, I would have a ballpark of my electrical endurance during alt-out and the rate at which the voltmeter was dropping would be a cross check. 	


   It's inarguable that a voltmeter COULD be used to

   assist you in worrying about what ever energy remains

   in the battery. I'll simply suggest this is something

   akin having discovered that you may not have accurately

   accounted for fuel necessary to make the leg . . .

   whereupon cursing those lousy fuel gages becomes a

   distraction to your piloting duties.



   Watching the voltmeter with an alternator dead

   is no less a distraction . . .

  	  Quote: 	
		   

 OK! I now think that a voltmeter is more useful for determining electrical endurance than an ammeter that just tells me my burn rate, which I already know from system architecture calcs. An ammeter is similar to a fuel flow meter. Knowing how much fuel you're burning is not particularly useful without knowing how much fuel you have. If you can see your fuel level, you can change throttle settings accordingly. Ditto on electricity. 	


   Well considered. May I further suggest that you

   are best served by having a well crafted Plan-B

   paired with a confidence that your well maintained

   equipment will perform as designed?



   So, when the light comes on, you need only

   configure for plan-B ops and arrange to be on the

   ground within parameters set by your well 

   considered and accurately achieved design goals.



   Once on the ground, you'll discover that troubleshooting

   the system requires voltmeters and/or ammeters

   to supplement any such indicators that already

   exist on the panel.



 

   Bob . . .    [quote][b]

jonlaury

Joined: 06 Nov 2006
Posts: 336

Posted: Wed Dec 23, 2009 7:51 am Post subject: Ammeter Help

 	  Quote: 	
		    	  Quote: 	
		        " If you have an electrically dependent engine then

         perhaps your plans should include a second alternator

         capable of supporting the engine . . ." I'm working on it. The available vacumn pad on my Franklin turns at about 0.8:1 so the B&C 20 amp aux alternator won't put out enough juice below 2400 eng rpm to keep my E-bus alive. The B&C "stack 'o pancakes" 30 amp model for Continentals has some promise of fitting in a fuel pump drive hole on the accessory case.Even without a spare alternator, I'm VFR comfortable with the triple redundancy of an alternator and two batteriesto keep the fires lit.

	
	


   [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Wed Dec 23, 2009 7:58 am Post subject: Ammeter Help

 	  Quote: 	
		   	  Quote: 	
		  

Even without a spare alternator, I'm VFR

comfortable with the triple redundancy of an alternator and two

batteriesto keep the fires

lit. 	
	


   Understand . . . let's strive to base your 'comfort'

   on knowing as much about watt-seconds in the batteries

   as you have gallons in the tanks.  



 

 

   Bob . . .    [quote][b]

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