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Measuring actual system current

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Sam

Joined: 18 May 2008
Posts: 135

Posted: Mon Feb 09, 2009 6:34 am Post subject: Measuring actual system current

Is there a way to measure the actual current draw of a system?  I finally got my electrically dependent engine started (www.samhoskins.blogspot.com) yesterday and I am using a version of Z-19/RB with a B&C 30A permemant magnet alternator.  I have the primary battery installed and a Dynon D180 EFIS/EMS.

  	  Quote: 	
		  	
I would like to be able to determine the real (not estimated) current draw of the system.  Once I know that, I will select the appropriate back-up battery, trying to keep it as light as possible.

 

There is an ammeter installed, but I don't think that would help for this data collection.  Does anyone have any suggestions how I might go about this?



Thanks.



Sam Hoskins

Murphysboro, IL

  [quote][b]

_________________
Sam Hoskins
www.samhoskins.blogspot.com

longg(at)pjm.com
Guest

Posted: Mon Feb 09, 2009 9:11 am Post subject: Measuring actual system current

Sam,  

   

Great looking aircraft! I’ve always loved that design. Keep those Vars up.  

   

Best of luck.  

   

Glenn  

     

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Sam Hoskins

 Sent: Monday, February 09, 2009 9:32 AM

 To: Aerolectric List

 Subject: Measuring actual system current  

  

   

Is there a way to measure the actual current draw of a system?  I finally got my electrically dependent engine started (www.samhoskins.blogspot.com) yesterday and I am using a version of Z-19/RB with a B&C 30A permemant magnet alternator.  I have the primary battery installed and a Dynon D180 EFIS/EMS.  

I would like to be able to determine the real (not estimated) current draw of the system.  Once I know that, I will select the appropriate back-up battery, trying to keep it as light as possible.

 

 There is an ammeter installed, but I don't think that would help for this data collection.  Does anyone have any suggestions how I might go about this?

 

 Thanks.

 

 Sam Hoskins

 Murphysboro, IL   	  Quote: 	
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dale.r(at)cox.net
Guest

Posted: Mon Feb 09, 2009 10:29 am Post subject: Measuring actual system current

Sam Hoskins wrote:

 	  Quote: 	
		   There is an ammeter installed, but I don't think that would help for 

 this data collection.  Does anyone have any suggestions how I might go 

 about this?




	


Umm ...  why not?  That's what an ammeter does.  The are some more 

sophisticated variations on the theme - load meters.

An ammeter can be inserted into any part of the system to measure the 

current of that branch and its dependent circuits.

It sounds like you just need an ammeter with sufficient granularity to 

measure more than gross changes in current draw.



Dale R.

COZY MkIV #0497

longg(at)pjm.com
Guest

Posted: Mon Feb 09, 2009 1:29 pm Post subject: Measuring actual system current

Sam,  

   

Just thought of something. Vertical sells that fancy box which claims to measure not only total draw, but the draw on each item at any given time. Unfortunately that’s big $$$.  I’ve not seen another system that performs that function independently.  

     

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Sam Hoskins

 Sent: Monday, February 09, 2009 9:32 AM

 To: Aerolectric List

 Subject: Measuring actual system current  

  

   

Is there a way to measure the actual current draw of a system?  I finally got my electrically dependent engine started (www.samhoskins.blogspot.com) yesterday and I am using a version of Z-19/RB with a B&C 30A permemant magnet alternator.  I have the primary battery installed and a Dynon D180 EFIS/EMS.  

I would like to be able to determine the real (not estimated) current draw of the system.  Once I know that, I will select the appropriate back-up battery, trying to keep it as light as possible.

 

 There is an ammeter installed, but I don't think that would help for this data collection.  Does anyone have any suggestions how I might go about this?

 

 Thanks.

 

 Sam Hoskins

 Murphysboro, IL   	  Quote: 	
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jon(at)finleyweb.net
Guest

Posted: Mon Feb 09, 2009 2:26 pm Post subject: Measuring actual system current

Hi Sam,

  

 I'm not an expert here so if somone corrects me, believe them!! 

  

 There are two ways that I know of (probably dozens of others).  If you have a multimeter, some of them will allow you to check the draw.  I have a cheap unit that states that it can handle 10 amp loads.  You have to break the circuit and run it "thru" the multimeter.  This works for the circuits that are easy to get at, not so well for others.  Last item on the following page:

 http://mechatronics.mech.northwestern.edu/design_ref/tools/multimeter.html

  

 The other way is to use of the clamp-on type meters. I don't own one of these but wish I did - should probably splurge on myself one of these days...

 http://support.fluke.com/find-sales/download/asset/2562791_6115_eng_a_w.pdf



 I have no doubt that this is a real cheapo (like everything HF sells) and I do not KNOW that it will do what we require but I think so:

 http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=98675

  

 Hth,

  

 Jon

  

 

--

frank.hinde(at)hp.com
Guest

Posted: Mon Feb 09, 2009 2:46 pm Post subject: Measuring actual system current

Negative, the HF clamp-on unit will NOT work. That  unit is for AC (alternating current) loads only, not DC (direct current) like  our airplanes are built. 

  

 However the cheapo DC HF multimeter I found to be  surprisingly accurate (calibrated it at work) and will measure up to 10A loads  and costs $2.99

  

 DO not forget to put the leads back in the correct  holes to measure voltage after you measured current though...If you forget and  try to measre mains voltage the unit will make a horrendous spark and cease to  function...My boss did just that checking out his water pump at home, much to my  amusement..

  

 Frank



   From:  owner-aeroelectric-list-server(at)matronics.com  [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of  jon(at)finleyweb.net

Sent: Monday, February 09, 2009 2:24  PM

To: aeroelectric-list(at)matronics.com

Subject: RE:  Measuring actual system current

 

 Hi Sam,

  

 I'm not an expert here so if somone corrects me, believe them!! 

  

 There are two ways that I know of (probably dozens of others).  If you  have a multimeter, some of them will allow you to check the draw.  I have a  cheap unit that states that it can handle 10 amp loads.  You have to break  the circuit and run it "thru" the multimeter.  This works for the circuits  that are easy to get at, not so well for others.  Last item on the  following page:

 http://mechatronics.mech.northwestern.edu/design_ref/tools/multimeter.html

  

 The other way is to use of the clamp-on type meters. I don't own one of  these but wish I did - should probably splurge on myself one of these  days...

 http://support.fluke.com/find-sales/download/asset/2562791_6115_eng_a_w.pdf



 I have no doubt that this is a real cheapo (like everything HF sells) and I  do not KNOW that it will do what we require but I think so:

 http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=98675

  

 Hth,

  

 Jon

  

 

--

Sam

Joined: 18 May 2008
Posts: 135

Posted: Mon Feb 09, 2009 3:54 pm Post subject: Measuring actual system current

The reason I can't use the ammeter, I think, is that the readings would be clouded by charging/discharging of the battery.  



Sam

 	  Quote: 	
		  	




 On Mon, Feb 9, 2009 at 12:25 PM, Dale Rogers <dale.r(at)cox.net (dale.r(at)cox.net)> wrote:

[quote] --> AeroElectric-List message posted by: Dale Rogers <dale.r(at)cox.net (dale.r(at)cox.net)>

 

 Sam Hoskins wrote:

  	  Quote: 	
		   There is an ammeter installed, but I don't think that would help for this data collection.  Does anyone have any suggestions how I might go about this?

 

 	
 



 Umm ...  why not?  That's what an ammeter does.  The are some more sophisticated variations on the theme - load meters.

 An ammeter can be inserted into any part of the system to measure the current of that branch and its dependent circuits.

 It sounds like you just need an ammeter with sufficient granularity to measure more than gross changes in current draw.

 

 Dale R.

 COZY MkIV #0497



 

 

 

 ===========

  -

 ric-List" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List

 ===========

 MS -

 k">http://forums.matronics.com

 ===========

 e -

           -Matt Dralle, List Admin.

 t="_blank">http://www.matronics.com/contribution

 ===========

 

 

 

 



[b]

_________________
Sam Hoskins
www.samhoskins.blogspot.com

msausen

Joined: 25 Oct 2007
Posts: 559
Location: Appleton, WI USA

Posted: Mon Feb 09, 2009 5:36 pm Post subject: Measuring actual system current

Calling it a fancy and expensive box that is used to measure total and individual draw leaves just a tiny bit of the functionality out.  J  

   

Michael  

Do not archive  

       

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of longg(at)pjm.com

 Sent: Monday, February 09, 2009 4:27 PM

 To: aeroelectric-list(at)matronics.com

 Subject: RE: Measuring actual system current  

  

  

   

Sam,  

   

Just thought of something. Vertical sells that fancy box which claims to measure not only total draw, but the draw on each item at any given time. Unfortunately that’s big $$$.  I’ve not seen another system that performs that function independently.  [quote] [b]

jon(at)finleyweb.net
Guest

Posted: Mon Feb 09, 2009 8:50 pm Post subject: Measuring actual system current

Hi Frank,  

   

Is it true that NO clamp-on unit will work or are you talking about just the unit that I referenced?  

   

Thanks!  

   

Jon  

       

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Hinde, Frank George (Corvallis)

 Sent: Monday, February 09, 2009 3:45 PM

 To: aeroelectric-list(at)matronics.com

 Subject: RE: Measuring actual system current  

  

  

   

   

   

Negative, the HF clamp-on unit will NOT work. That unit is for AC (alternating current) loads only, not DC (direct current) like our airplanes are built.   

   

However the cheapo DC HF multimeter I found to be surprisingly accurate (calibrated it at work) and will measure up to 10A loads and costs $2.99  

   

DO not forget to put the leads back in the correct holes to measure voltage after you measured current though...If you forget and try to measre mains voltage the unit will make a horrendous spark and cease to function...My boss did just that checking out his water pump at home, much to my amusement..  

   

Frank  

       

  

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of jon(at)finleyweb.net

 Sent: Monday, February 09, 2009 2:24 PM

 To: aeroelectric-list(at)matronics.com

 Subject: RE: Measuring actual system current    

Hi Sam,  

    

   

    

I'm not an expert here so if somone corrects me, believe them!!   

    

   

    

There are two ways that I know of (probably dozens of others).  If you have a multimeter, some of them will allow you to check the draw.  I have a cheap unit that states that it can handle 10 amp loads.  You have to break the circuit and run it "thru" the multimeter.  This works for the circuits that are easy to get at, not so well for others.  Last item on the following page:  

    

http://mechatronics.mech.northwestern.edu/design_ref/tools/multimeter.html  

    

   

    

The other way is to use of the clamp-on type meters. I don't own one of these but wish I did - should probably splurge on myself one of these days...  

    

http://support.fluke.com/find-sales/download/asset/2562791_6115_eng_a_w.pdf  

    

I have no doubt that this is a real cheapo (like everything HF sells) and I do not KNOW that it will do what we require but I think so:  

    

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=98675  

    

   

    

Hth,  

    

   

    

Jon  

    

   

  

       [quote][b]

airelectricjim

Joined: 09 Jan 2009
Posts: 11
Location: Augusta GA USA

Posted: Tue Feb 10, 2009 8:35 am Post subject: Measuring actual system current

Sam (and List),



Frank is right -- the Fluke meters Jon referenced won't work on DC.  Fluke

(Cadillac of meters) does sell DC clamp meters, for MANY hundreds of

dollars!  However, here's a reference to a Craftsman AC/DC clamp meter that

works well, for about 60 bucks:

http://www.sears.com/shc/s/p_10153_12605_03482369000P?mv=rr



Blue skies and tailwinds



Jim

CH-801

DeltaHawk diesel

Augusta GA

90% done, 90% left

_________________
Jim
Zenith CH801
DeltaHawk diesel
jmcburney@pobox.com

kuffel(at)cyberport.net
Guest

Posted: Tue Feb 10, 2009 9:40 am Post subject: Measuring actual system current

Sam,

  

 << Is  there a way to measure the actual current draw of a system?  ..  Dynon D180 EFIS/EMS.  >>

  

 The D180 comes  with an accurate current shunt.  If you installed your shunt as an  alternator load meter (Position B of page 3-12 of the current [Rev  E] D180 Installation Manual, between the alternator output and everything  else) then temporarily install it in Position A (between the output of the  Master Relay and everything else but the Starter Relay) or Position C (between  the junction of the Master Relay - Alternator Output and the aircraft buss)  whichever is mechanically easier.

  

 Start your  engine, charge up the battery and then turn off the alternator if your  shunt is in Position A.  The Dynon will now give you detailed readout of  current draw (and difference in draw) with various pieces turned on or  off.  The one item missing is the current draw for the Master Relay.   My B&C 4-terminal style Master Relay uses 0.70  amps.

  

 Tom  Kuffel

 



    [quote][b]

dale.r(at)cox.net
Guest

Posted: Tue Feb 10, 2009 1:23 pm Post subject: Measuring actual system current

Sam Hoskins wrote:

 	  Quote: 	
		   The reason I can't use the ammeter, I think, is that the readings 

 would be clouded by charging/discharging of the battery. 


	


Nope.  An ammeter measures current passing through it - period.  ~The~ 

airplane ammeter is just placed between the battery and ~everything 

else~.  To measure current in a branch circuit, you need another 

ammeter.  Open the circuit you want to check and insert the ammeter (or 

ammeter/shunt combo).  Run the device(s) you want verified; measure the 

current draw.



When testing is complete remove ammeter and restore original circuit 

configuration.



Dale R.

Allen Fulmer

Joined: 10 Jan 2006
Posts: 79
Location: Alexander City, AL

Posted: Tue Feb 10, 2009 2:03 pm Post subject: Measuring actual system current

I bought one of these recommended by someone else.  Seems to work fine and

nice addition to toolbox.



http://www.extech.com/instrument/products/alpha/MA220.html



Allen Fulmer

_________________
RV7 QB Fuselage
Eggenfellner H6 on orde
N808AF reserved
Alexander City, AL

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Feb 10, 2009 7:37 pm Post subject: Measuring actual system current

At 08:31 AM 2/9/2009, you wrote:

  	  Quote: 	
		  Is there a way to measure the actual current draw of a system?  I finally got my electrically dependent engine started ( www.samhoskins.blogspot.com) yesterday and I am using a version of Z-19/RB with a B&C 30A permemant magnet alternator.  I have the primary battery installed and a Dynon D180 EFIS/EMS.

  

  I would like to be able to determine the real (not estimated) current draw of the system.  Once I know that, I will select the appropriate back-up battery, trying to keep it as light as possible.



 There is an ammeter installed, but I don't think that would help for this data collection.  Does anyone have any suggestions how I might go about this? 	


   If you have breakers, then open the breaker that supplies

   the load of interest and clip an ammeter across the open

   breaker. If you have fuses, pull the fuse and clip the

   meter between the fat power stud at the end of the fuseholder

   and the other end to the output tab for that fuse.



   Even the cheapest multimeter you can find will do for

   this task. 



  http://aeroelectric.com/Pictures/Tools/Test_Equipment/tenma1.jpg



   Harbor Freight sells something like this for about $3 on

   sale . . . regularly $9 I think.



   For your task, I recommend you cut the probes off of the

   test leads and install alligator clips with rubber booties

   over them so that you can do "clip on" connections that

   will stay in place while you manipulate ship's accessories

   taking measurements.



   If you're interested in e-bus loads, clip the mulitmeter

   across an open e-bus alternate feed switch with the

   battery master OFF. This will get you the total e-bus

   load which is quite useful for adjusting battery size.



   Remember that a battery's useful capacity goes DOWN as

   load increases. A 17 a.h. battery is good for that

   amount with a 20 hour discharge rate. When you hang

   say a 4A e-bus load on it, you won't get the full

   17 a.h. . . . it will be more like 13-14 a.h.



   Bob . . .    [quote][b]

Sam

Joined: 18 May 2008
Posts: 135

Posted: Wed Feb 11, 2009 4:44 am Post subject: Measuring actual system current

That sounds good.  I can measure one circuit at a time, i.e. ignition coil circuit, fuel injector circuit, etc.



Thanks to all who replied.



Sam Hoskins

www.samhoskins.blogspot.com

  	  Quote: 	
		  	




On Tue, Feb 10, 2009 at 9:35 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

 [quote]  At 08:31 AM 2/9/2009, you wrote:

 

 	  Quote: 	
		  Is there a way to measure the actual current draw of a system?  I finally got my electrically dependent engine started ( www.samhoskins.blogspot.com) yesterday and I am using a version of Z-19/RB with a B&C 30A permemant magnet alternator.  I have the primary battery installed and a Dynon D180 EFIS/EMS.

  

  I would like to be able to determine the real (not estimated) current draw of the system.  Once I know that, I will select the appropriate back-up battery, trying to keep it as light as possible.

 There is an ammeter installed, but I don't think that would help for this data collection.  Does anyone have any suggestions how I might go about this?

	


   If you have breakers, then open the breaker that supplies

   the load of interest and clip an ammeter across the open

   breaker. If you have fuses, pull the fuse and clip the

   meter between the fat power stud at the end of the fuseholder

   and the other end to the output tab for that fuse.



   Even the cheapest multimeter you can find will do for

   this task. 



  http://aeroelectric.com/Pictures/Tools/Test_Equipment/tenma1.jpg



   Harbor Freight sells something like this for about $3 on

   sale . . . regularly $9 I think.



   For your task, I recommend you cut the probes off of the

   test leads and install alligator clips with rubber booties

   over them so that you can do "clip on" connections that

   will stay in place while you manipulate ship's accessories

   taking measurements.



   If you're interested in e-bus loads, clip the mulitmeter

   across an open e-bus alternate feed switch with the

   battery master OFF. This will get you the total e-bus

   load which is quite useful for adjusting battery size.



   Remember that a battery's useful capacity goes DOWN as

   load increases. A 17 a.h. battery is good for that

   amount with a 20 hour discharge rate. When you hang

   say a 4A e-bus load on it, you won't get the full

   17 a.h. . . . it will be more like 13-14 a.h.



   Bob . . .     	  Quote: 	
		  



ist" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List

tp://forums.matronics.com

_blank">http://www.matronics.com/contribution



	




[b]

_________________
Sam Hoskins
www.samhoskins.blogspot.com

klehman(at)albedo.net
Guest

Posted: Wed Feb 11, 2009 5:18 am Post subject: Measuring actual system current

Maybe not.

A digital amp meter can give inaccurate readings when measuring the 

short current pulses that occur on these circuits. And the current will 

vary with rpm. Might be OK but I would trust an analog meter more if I 

wanted average current for sizing the alternator. For sizing wires and 

fuses, I measured the resistance of the associated coil and calculated 

the peak current. The wire sizes and fuses that were used in the 

automobile then made sense.

Ken



Sam Hoskins wrote:

 	  Quote: 	
		   That sounds good.  I can measure one circuit at a time, i.e. ignition 

 coil circuit, fuel injector circuit, etc.

 

 Thanks to all who replied.

 

 Sam Hoskins

 www.samhoskins.blogspot.com <http://www.samhoskins.blogspot.com>

Sam

Joined: 18 May 2008
Posts: 135

Posted: Wed Feb 11, 2009 5:49 am Post subject: Measuring actual system current

I have an old favorite analog Triplett meter that might be just the trick.

 	  Quote: 	
		  	
Sam



On Wed, Feb 11, 2009 at 7:19 AM, Ken <klehman(at)albedo.net (klehman(at)albedo.net)> wrote:

 [quote]--> AeroElectric-List message posted by: Ken <klehman(at)albedo.net (klehman(at)albedo.net)>

  

 Maybe not.

 A digital amp meter can give inaccurate readings when measuring the short current pulses that occur on these circuits. And the current will vary with rpm. Might be OK but I would trust an analog meter more if I wanted average current for sizing the alternator. For sizing wires and fuses, I measured the resistance of the associated coil and calculated the peak current. The wire sizes and fuses that were used in the automobile then made sense.

  Ken

 

 Sam Hoskins wrote:

  	  Quote: 	
		   That sounds good.  I can measure one circuit at a time, i.e. ignition coil circuit, fuel injector circuit, etc.

 

 Thanks to all who replied.

 

 Sam Hoskins

 

www.samhoskins.blogspot.com <http://www.samhoskins.blogspot.com>

 

 	


 

 ===========

  -

 ric-List" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List

 ===========

 MS -

 k">http://forums.matronics.com

 ===========

 e -

           -Matt Dralle, List Admin.

 t="_blank">http://www.matronics.com/contribution

 ===========

 

 

 

 



[b]

_________________
Sam Hoskins
www.samhoskins.blogspot.com

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