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building a batter capacity tester

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Michael Wynn

Joined: 10 Jan 2006
Posts: 148
Location: San Ramon, CA

Posted: Sun Sep 11, 2011 1:56 pm Post subject: building a batter capacity tester

I have been following the PC680 thread with great interest.  I have a  couple for my RV8 that have been sitting around longer than I had meant for them  to sit.  You know how construction goes.  

  

 I was going to build the capacity tester from the aeroelectric site:

  

 http://www.aeroelectric.com/articles/battest.pdf

  

 This looks pretty straightforward and I assume that I can get all the  components from my local Radio Shack.  The one thing I am foggy on is the  10 V. Zener diode in the schematic.  Never having used these, are they sold  by voltage or amperage or what.  Specifically, how do I make sure I get the  correct component?

  

 Thanks,

  

 Michael Wynn

 RV 8 Wiring

 San Ramon, CA

  

  In a message dated 9/11/2011 12:09:07 P.M. Pacific Daylight Time,  paulm(at)olypen.com writes:

 [quote]-->    AeroElectric-List message posted by: "Paul"    <paulm(at)olypen.com>

---

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_________________
Michael Wynn
RV 8
San Ramon, CA

retasker(at)optonline.net
Guest

Posted: Sun Sep 11, 2011 7:14 pm Post subject: building a batter capacity tester

Pretty much any 10V zener diode will work there.  Zeners are sold by voltage since that is their purpose (to control the voltage across their terminals).  The other thing that is important is the 

wattage rating, although in this case the power dissipated by the zener is so low (50mW) that any 10V zener you can buy will work.



Dick Tasker



MLWynn(at)aol.com wrote:

[quote] I have been following the PC680 thread with great interest.  I have a couple for my RV8 that have been sitting around longer than I had meant for them to sit.  You know how construction goes.

 I was going to build the capacity tester from the aeroelectric site:

 http://www.aeroelectric.com/articles/battest.pdf

 This looks pretty straightforward and I assume that I can get all the components from my local Radio Shack.  The one thing I am foggy on is the 10 V. Zener diode in the schematic.  Never having used 

 these, are they sold by voltage or amperage or what.  Specifically, how do I make sure I get the correct component?

 Thanks,

 Michael Wynn

 RV 8 Wiring

 San Ramon, CA

 In a message dated 9/11/2011 12:09:07 P.M. Pacific Daylight Time, paulm(at)olypen.com writes:



     

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Mauledriver(at)nc.rr.com
Guest

Posted: Mon Sep 12, 2011 2:52 am Post subject: building a batter capacity tester

Just a quick update on my PC680 odyssey.... while 1 battery was     beyond hope, 2 that I had removed for poor performance recovered     enough to pass the minimum test as defined by the manufacturer - 

     >12.65 volts with no load, 

     > 9.6 volts (at)70F with 120amp load for 15 seconds

     My oldest battery, a3+ year old Odyssey PC680 that has only been     trickled charged, tests at 12.89volts with no load and 10.8 volts at     end of load test.

     A 'new' battery a neighbor gave me, the certified version of the     PC680, 13.18 with no load and 10.0 volts at end of test

     

     How did they recover?  A couple of charges/discharges with a 10amp     Schumacher charger (model XC10).

     

     The 2 batteries I have installed in my '10 have 'recovered' too.      Though I haven't had a chance to test them with the HF tester     recently, batt1 has been discharged with extensive panel work and     batt2 has given me 10+ starts.  They've been charged on a number of     1 & 2 hour flights.  They now both perform almost as desired,     i.e. batt1 will run  my panel for extended periods without losing     the 3 GRTs due to low voltage, batt2 gets thru the first compression     stroke on the first try... sometimes just barely and it  is     certainly not 'snappy'.

     

     I can run with what I have for now.  Cold weather may change     things.  My sense is that 1 or 2 fresh batteries  will give me what     I want in the end.  A different starter may still be desirable for     better starts in cold conditions.

     

     PS - the certified version of the 680 labled "PowerSafe - SBS J16     from Enersys" seems to perform differently.  Though it is physically     identical except for color, it appears to have different     characteristics under load.  Not necessarily better.

     

     Bill "smiling ear to ear with the new OBAM plane" Watson

     

     

     On 9/11/2011 5:50 PM, MLWynn(at)aol.com (MLWynn(at)aol.com) wrote:     [quote]                              I have been following the PC680 thread with great           interest.  I have a couple for my RV8 that have been sitting           around longer than I had meant for them to sit.  You know how           construction goes.  

          

         I was going to build the capacity tester from the           aeroelectric site:

          

         http://www.aeroelectric.com/articles/battest.pdf

          

         This looks pretty straightforward and I assume that I can           get all the components from my local Radio Shack.  The one           thing I am foggy on is the 10 V. Zener diode in the           schematic.  Never having used these, are they sold by voltage           or amperage or what.  Specifically, how do I make sure I get           the correct component?

          

         Thanks,

          

         Michael Wynn

         RV 8 Wiring

         San Ramon, CA

          

                    In a message dated 9/11/2011 12:09:07 P.M. Pacific             Daylight Time, paulm(at)olypen.com (paulm(at)olypen.com) writes:

           [quote]-->               AeroElectric-List message posted by: "Paul"               <paulm(at)olypen.com> (paulm(at)olypen.com)

               

               

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nuckolls.bob(at)aeroelect
Guest

Posted: Mon Sep 12, 2011 5:31 am Post subject: building a batter capacity tester

At 04:50 PM 9/11/2011, you wrote:

  	  Quote: 	
		   I have been following the PC680 thread with great interest.  I have a couple for my RV8 that have been sitting around longer than I had meant for them to sit.  You know how construction goes.  

  

 I was going to build the capacity tester from the aeroelectric site:

  

  http://www.aeroelectric.com/articles/battest.pdf

  

 This looks pretty straightforward and I assume that I can get all the components from my local Radio Shack.  The one thing I am foggy on is the 10 V. Zener diode in the schematic.  Never having used these, are they sold by voltage or amperage or what.  Specifically, how do I make sure I get the correct component? 	


    Keep in mind that this is more of a battery

    bench-marker as opposed to a quantitative

    tester.



    A battery's ability to deliver energy depends

    on size, condition, temperature and load. A

    battery 'rated' at 20AH will deliver that amount

    of output when new and generally under a very

    light load compared to how you intend to used it.



    Consider the exemplar plot below



 [img]cid:.0[/img]



     This battery is 'rated' at 17 a.h. But it will

     deliver that output only when loaded at .85A x

     20 hours = 17 a.h.  Your airplane's endurance

     loads are more likely to be on the order of 4A

     so you can expect about 3 hours of service or

     12.75 a.h. of output. Of course, this is an as-new

     performance value. You'll want to size and maintain

     your battery to meed design goals when the battery

     has just degraded to the point of needing replacement.

     For most folks this is at 75 or 80% of new capacity.



     So this particular battery could be used in a system

     where endurance expectations are for 2 hours of

     service at 4.25A.



     The battery cap tester depicted in the book is

     not intended to give you an accurate reading of

     the battery's capacity. What it will do is let

     you know when the battery has fallen so far below

     its as-new condition as to require replacement.

     If your new battery ran your exemplar load for say

     200 minutes, then you would benchmark the replacement

     at 150 minutes.



     If you'd like to get real numbers at loads matching

     your system's requirements, you'll need something like



  http://www.westmountainradio.com/product_info.php?products_id=cba3&navcode=/cbaLink1

 

     I've got a couple of these critters. They were used

     to produce the plots like these



  http://www.aeroelectric.com/Pictures/Curves/HF_aa_vs_Duracell.jpg

  http://www.aeroelectric.com/Pictures/Curves/El-Cheeso_Battery_Test_3.jpg 



     The device can also be used as a voltage versus time

     data acquisition system and get you information like

     this.



  http://www.aeroelectric.com/Pictures/Curves/schumacher_3.jpg



     I would not discourage you from building the po' boy's

     cap-checker. It's a useful tool within its limitations.

     Radio Shack won't have a 10v zener. You'll have to get

     it from a supplier with a broader range of product offerings.



     I'll be back in my shop later today. Let me see if I've

     got one in drawer I can send you.



     Bob . . .

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Michael Wynn

Joined: 10 Jan 2006
Posts: 148
Location: San Ramon, CA

Posted: Wed Sep 14, 2011 9:54 pm Post subject: building a batter capacity tester

Hey Bob,

  

 I was looking over the specs on the West Mountain battery analyzer you  mentioned:

 http://www.westmountainradio.com/product_info.php?products_id=cba3&navcode=/cbaLink1

  

 This is a very elegant piece of equipment.  The information that it  provides is certainly several magnitudes of more exact than the poor man's bench  tester I was thinking to build.  Further, it seems like something that my  EAA chapter could put to more regular use than I would on my own.  It is  more than it would cost me to build the other, but not ridiculously  expensive. Thank you for the direction.

  

 With this piece of equipment, would there be any reason to also have a  carbon pile load tester?  Harbor Freight has one on sale for  $49.95.  It seems to me that I would get much more useful data from the  West Mountain unit and could save on that expense.

  

 Regards, 

  

 Michael Wynn

 RV 8 Wiring

 San Ramon, CA

  In a message dated 9/12/2011 6:32:41 A.M. Pacific Daylight Time,  nuckolls.bob(at)aeroelectric.com writes:

  	  Quote: 	
		  At 04:50    PM 9/11/2011, you wrote:

    	  Quote: 	
		  I have been following the PC680 thread with great      interest.  I have a couple for my RV8 that have been sitting around      longer than I had meant for them to sit.  You know how construction      goes.  

 

I was going to build the capacity tester from the      aeroelectric site:

 

http://www.aeroelectric.com/articles/battest.pdf

 

This      looks pretty straightforward and I assume that I can get all the components      from my local Radio Shack.  The one thing I am foggy on is the 10 V.      Zener diode in the schematic.  Never having used these, are they sold      by voltage or amperage or what.  Specifically, how do I make sure I get      the correct component? 	


   Keep in mind that    this is more of a battery

   bench-marker as opposed to a    quantitative

   tester.



   A battery's ability    to deliver energy depends

   on size, condition, temperature and    load. A

   battery 'rated' at 20AH will deliver that    amount

   of output when new and generally under a    very

   light load compared to how you intend to used    it.



   Consider the exemplar plot    below



    This battery is 'rated' at 17 a.h. But    it will

    deliver that output only when loaded at .85A    x

    20 hours = 17 a.h.  Your airplane's    endurance

    loads are more likely to be on the order of    4A

    so you can expect about 3 hours of service    or

    12.75 a.h. of output. Of course, this is an    as-new

    performance value. You'll want to size and    maintain

    your battery to meed design goals when the    battery

    has just degraded to the point of needing    replacement.

    For most folks this is at 75 or 80% of new    capacity.



    So this particular battery could be used    in a system

    where endurance expectations are for 2 hours    of

    service at 4.25A.



    The    battery cap tester depicted in the book is

    not intended    to give you an accurate reading of

    the battery's    capacity. What it will do is let

    you know when the     battery has fallen so far below

    its as-new condition as    to require replacement.

    If your new battery ran your    exemplar load for say

    200 minutes, then you would    benchmark the replacement

    at 150    minutes.



    If you'd like to get real numbers at loads    matching

    your system's requirements, you'll need    something like



http://www.westmountainradio.com/product_info.php?products_id=cba3&navcode=/cbaLink1



       I've got a couple of these critters. They were used

    to    produce the plots like these



http://www.aeroelectric.com/Pictures/Curves/HF_aa_vs_Duracell.jpg

http://www.aeroelectric.com/Pictures/Curves/El-Cheeso_Battery_Test_3.jpg    



    The device can also be used as a voltage versus    time

    data acquisition system and get you information    like

    this.



http://www.aeroelectric.com/Pictures/Curves/schumacher_3.jpg



       I would not discourage you from building the po' boy's

       cap-checker. It's a useful tool within its limitations.

       Radio Shack won't have a 10v zener. You'll have to get

       it from a supplier with a broader range of product    offerings.



    I'll be back in my shop later today. Let    me see if I've

    got one in drawer I can send    you.



    Bob . . .  	


 [quote][b]

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_________________
Michael Wynn
RV 8
San Ramon, CA

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Sep 15, 2011 6:09 am Post subject: building a batter capacity tester

From: MLWynn(at)aol.com

 Subject: Re: building a batter capacity tester

 To: aeroelectric-list(at)matronics.com 



 

 Hey Bob,

  

 I was looking over the specs on the West Mountain battery analyzer you mentioned:

  http://www.westmountainradio.com/product_info.php?products_id=cba3&navcode=/cbaLink1

  

 This is a very elegant piece of equipment.  The information that it provides is certainly several magnitudes of more exact than the poor man's bench tester I was thinking to build.  Further, it seems like something that my EAA chapter could put to more regular use than I would on my own.  It is more than it would cost me to build the other, but not ridiculously expensive. Thank you for the direction.



     Yeah, those are a really good value. I have two

     of them. I wish they were a little more robust . . .

     say good for 10+ amps while testing a 12v battery

     but I HAVE used them to gather a lot of good data.



     It was a couple of years into my ownership that it

     suddenly occurred to me that they could be used for

     long term voltage monitoring and plotting.

     Set it up to 'test' a battery with a 0.01 amp

     load and a very low 'cutoff voltage' then hook

     the test leads to the source being monitored.    

  

 With this piece of equipment, would there be any reason to also have a carbon pile load tester?  Harbor Freight has one on sale for $49.95.  It seems to me that I would get much more useful data from the West Mountain unit and could save on that expense.



     BOTH devices are useful for different reasons. But

     they can be used together too.



     LOAD testing is measure of a battery's internal

     impedance . . . I.e. ability to carry a large load.



     CAP testing is a measure of available energy at

     the terminals under various loads . . . where

     we know that useful energy is adversely influenced

     by internal impedance. There's more than enough

     ENERGY in a couple of alkaline lantern batteries

     to start an engine and the West Mountain Radio

     device would confirm that assertion. Problem is

     that a string of "F-cells" wont dump that energy

     at 200+ amps.



     Your load tester can be used to check your car's

     alternator too. Hook a voltmeter to the alternator's

     b-lead terminal while putting a load on the battery

     equal to the alternator's rated output with the engine

     rpms above 2000 or so. The drop should be nominal . . .

     perhaps 0.5 volts max. It might even go UP a bit!



     The WMR cap tester will characterize your battery's

     ability to support endurance loads for an interval

     set my your design goals. The load tester cannot

     measure or even help predict that.



     I considered doing a kit product consisting of a

     USB linked micro-controller and a really FAT mos-fet

     but with no heat-sink. Modern computers have a really

     great CPU heatsink and fan assembly that one can acquire

     from dead computers. A bill of materials for the

    hardware is about $15.00. 



    The hardware is simple . . . the software for

    a graphical user interface and data plotting

    is a significant task that I just don't have

    time to address. If anyone out there is really

    whippy in Visual C or some similarly capable

    language, we might consider a joint venture

    to offer a kit for a DIY cap meter with some

    really nice features.



 

 

   Bob . . .    [quote][b]

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