Matronics Email Lists :: View topic - Battery capacity testing

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Battery capacity testing

Matronics Email Lists Forum Index -> AeroElectric-List

View previous topic :: View next topic

Author Message

dan(at)familybrown.org
Guest

Posted: Mon Oct 05, 2009 8:59 am Post subject: Battery capacity testing

I fly a Mooney M20F which has a Concorde RG battery installed  

(RG-35AXC).  Concorde (as well as Bob, of course) recommend periodic  

capacity testing--after 2 years, and every year thereafter.



The procedure called for in Concorde's ICA  

(http://www.concordebattery.com/otherpdf/IFCA1.pdf, page  is to load  

the battery at the 1-hour rate (33 amps, in my case), and see how long  

it takes for the voltage to drop below 10 volts.  If that takes less  

than 51 minutes (85% of 1 hour) on a fully-charged battery, it is to  

be replaced.



So the question is, how can I uniformly (and, ideally, inexpensively)  

load the battery to 33 amps?  I'd think that the loading would be  

fairly critical to get a valid result.  Of course, I could do the math  

easily enough if the load were some other constant value (say, 30 or  

35 amps), but I don't think I'd get a very good result with a load  

that changed over time (like using a light bulb), since it'd be hard  

to integrate that into total amp-hours.



I've looked at West Mountain Radio's CBA-III  

(http://www.westmountainradio.com/CBA_ham.htm), but to work for this  

purpose it would also need their add-on amplifier accessory  

(http://www.westmountainradio.com/CBAAmplifier.htm), bringing the  

total cost to almost $900.



What other options are out there?



-- 

Dan Brown, KE6MKS, dan(at)familybrown.org

"Since all the world is but a story, it were well for thee to buy the

more enduring story rather than the story that is less enduring."

  -- The Judgment of St. Colum Cille

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Oct 05, 2009 9:42 am Post subject: Battery capacity testing

At 11:55 AM 10/5/2009, you wrote:

 	  Quote: 	
		  



I fly a Mooney M20F which has a Concorde RG battery installed

(RG-35AXC).  Concorde (as well as Bob, of course) recommend periodic

capacity testing--after 2 years, and every year thereafter.




	


  <snip>

 	  Quote: 	
		  I've looked at West Mountain Radio's CBA-III

(http://www.westmountainradio.com/CBA_ham.htm), but to work for this

purpose it would also need their add-on amplifier accessory

(http://www.westmountainradio.com/CBAAmplifier.htm), bringing the

total cost to almost $900.


	


   Yeah . . . lots of overkill if YOUR are interested

   in endurance AS INSTALLED in YOUR airplane with YOUR

   choice of equipment items operational.



   The "approved" testing protocols come from a bunch

   of bureaucrats who decided some years ago that

   EVERYBODY's airplane should be configured and

   maintained to get on the ground in 30 minutes

   or less after engine driven power goes away.



   How about this? YOU decide what your

   alternator-out endurance target is. Wouldn't

   you feel better about 1 hour? How about two

   hours? Next make up a list of electro-whizzies

   you plan to leave ON (and those you can't turn

   off) after the LV warning light comes on.



   During some CAVU cross country, deliberately

   put your airplane into a failed alternator

   condition and start your stop-watch. 11 volts

   is a better battery depleted target. See:



http://www.aeroelectric.com/Pictures/Curves/28AH_12V_Capacity_vs_Load.gif



   Note that by the time a 12 lead-acid battery

   drops to 11.0 volts, the curve is VERY steep

   and 10.0 volts is not far behind.



   When your battery drops to 11.0 volts, note

   the time it took to get down to that value.

   Did that meet your design goal for battery only

   endurance?



   No? (1) replace battery. (2) revise electrical

   load for alternator out operations or (3)

   revise endurance design goals. Or some combination

   of the 3.



   I think it's much better that the owner/operator

   craft, test and maintain personally generated

   endurance goals. Your chances of understanding

   and operating your airplane with confidence is

   greatly improved.



   After 11.0V is achieved, turn the alternator

   back on. Turn on maximum number of electro-whizzies

   for 10 minutes or so to mitigate the initial

   inrush of battery recharge currents. After 10

   minutes, reduce to minimum required for completing

   the flight. If you have a battery maintainer to

   hook to you battery in the hangar, it's always

   a good thing whether or not you just tested

   the battery.

        Bob . . .



         ---------------------------------------

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

         ---------------------------------------

dan(at)familybrown.org
Guest

Posted: Mon Oct 05, 2009 6:16 pm Post subject: Battery capacity testing

-----BEGIN PGP SIGNED MESSAGE-----

Hash: SHA1



Robert L. Nuckolls, III wrote:



 	  Quote: 	
		     During some CAVU cross country, deliberately

   put your airplane into a failed alternator

   condition and start your stop-watch. 11 volts


	


Well, I've inadvertently done this (and due to the lack of active

low-voltage warning, since rectified, didn't realize it), and I lasted

about 3 hours before the GNS-430 shut down.  Not realizing that the

alternator was inop, I was running ordinary daytime equipment.



Interestingly, it was my altitude encoder that was first to go (got a

number of calls from ATC that they weren't picking up my Mode C

readout).  After that, the display on my engine monitor (instrument

itself kept working, but the display was dark).  The KX-155 lasted the

longest before going dark.



Given my ordinary daytime system load of 10-12 amps, the battery would

have to be very far gone indeed before it would give me less than an

hour, and even 2 hours would only be about 2/3 of its rated capacity

(well below the point where I should, according to the manufacturer,

discard the battery).



With normal daytime loads, and the battery at full capacity, empirical

observation and calculations agree that I get about 3 hours.  At 85%

capacity, the point where the ICAs specify battery replacement, that

would leave 2.5 hours.  I'm not going to have "duration of fuel aboard"

as my battery life (and never will on the Mooney without shedding _lots_

of load--fuel capacity is 6-7 hours), but that would give plenty of time

 to land.  Now that I have the flashing red light for low voltage, I'll

know about a problem right away, too.



What all this doesn't tell me is the health of the battery on an ongoing

basis.  I'd think there should be a better way to test this than

repeatedly failing the alternator in flight.



- --

Dan Brown, KE6MKS, dan(at)familybrown.org

"Since all the world is but a story, it were well for thee to buy the

more enduring story rather than the story that is less enduring."

 -- The Judgment of St. Colum Cille

-----BEGIN PGP SIGNATURE-----

Version: GnuPG v1.2.1 (MingW32)

Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/



iD8DBQFKyqduyQGUivXxtkERAkiZAJoDhyImplMMbkqLsjATGa0WKPhehQCggb9U

HKxRHF41VQs7mPWmFVYvX3I=

=WonS

-----END PGP SIGNATURE-----

Kellym

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

Posted: Tue Oct 06, 2009 4:36 am Post subject: Battery capacity testing

Caution.........Unless it is a very early M20F, the gear and possibly 

the flaps are electrically operated. I would not recommend running the 

battery low enough to force lowering the gear by the emergency 

extension. Seems like this would be an issue for all retractables that 

use electric power for gear operation.

Or are you suggesting staying airborne while you reactivate the 

alternator field and giving it some time to recharge the battery? Seems 

like that would abuse the battery with high charging rates.

Perhaps testing by monitoring voltage and time, 30 min. with a 

conservative volts cutoff(12.0?), whichever comes first might be safer, 

at least for a first try.

Robert L. Nuckolls, III wrote:

 	  Quote: 	
		  > I fly a Mooney M20F which has a Concorde RG battery installed

> (RG-35AXC).  Concorde (as well as Bob, of course) recommend periodic

> capacity testing--after 2 years, and every year thereafter.

 	  Quote: 	
		     Yeah . . . lots of overkill if YOUR are interested

   in endurance AS INSTALLED in YOUR airplane with YOUR

   choice of equipment items operational.

 	  Quote: 	
		     How about this? YOU decide what your

   alternator-out endurance target is. Wouldn't

   you feel better about 1 hour? How about two

   hours? Next make up a list of electro-whizzies

   you plan to leave ON (and those you can't turn

   off) after the LV warning light comes on.

   During some CAVU cross country, deliberately

   put your airplane into a failed alternator

   condition and start your stop-watch. 11 volts

   is a better battery depleted target. See:

 http://www.aeroelectric.com/Pictures/Curves/28AH_12V_Capacity_vs_Load.gif

   Note that by the time a 12 lead-acid battery

   drops to 11.0 volts, the curve is VERY steep

   and 10.0 volts is not far behind.

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

mrspudandcompany(at)veriz
Guest

Posted: Tue Oct 06, 2009 5:26 am Post subject: Battery capacity testing

What all this doesn't tell me is the health of the battery on an ongoing

basis.  I'd think there should be a better way to test this than

repeatedly failing the alternator in flight.

Dan,



Catastrophic battery failure is rare.  If you do this test one or two times

a year it will give you a good on-going test of the general battery health.



If you want to do a more quantitative test of your battery capacity then I

would suggest that you use the procedure documented on Bob N's website.



Roger

dan(at)familybrown.org
Guest

Posted: Tue Oct 06, 2009 5:26 am Post subject: Battery capacity testing

Quoting Kelly McMullen <kellym(at)aviating.com>:



 	  Quote: 	
		   Caution.........Unless it is a very early M20F, the gear and  

 possibly the flaps are electrically operated. I would not recommend  

 running


	


In my case, the plane has manual gear and flaps.  That said, I think  

Bob's recommendation was to reengage the alternator and let it charge  

for a bit before landing.



-- 

Dan Brown, KE6MKS, dan(at)familybrown.org

"Since all the world is but a story, it were well for thee to buy the

more enduring story rather than the story that is less enduring."

  -- The Judgment of St. Colum Cille

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Oct 08, 2009 8:57 am Post subject: Battery capacity testing

At 07:32 AM 10/6/2009, you wrote:

 	  Quote: 	
		  



Caution.........Unless it is a very early M20F, the gear and 

possibly the flaps are electrically operated. I would not recommend 

running the battery low enough to force lowering the gear by the 

emergency extension. Seems like this would be an issue for all 

retractables that use electric power for gear operation.


	


    I suggested that such testing be accomplished

    under very low risk conditions at altitude.

    As soon as the alternator is back on line, there

    will be enough snort to operate the devices you

    mentioned just from the alternator's output . . .

    and a few minutes later, the battery will have

    stored up enough to operate flaps and/or gear.



    If your battery is in really good shape and still

    above 11.0 volts when 20-20 minutes out, it's probably

    a good idea to terminate the experiment and pay

    attention to pilot business. Conducted with prudence,

    this is a low-priority, low-risk experiment that

    will produce a very accurate assessment of your

    battery's ability to perform to YOUR design goals.

 	  Quote: 	
		  Or are you suggesting staying airborne while you reactivate the 

alternator field and giving it some time to recharge the battery? 

Seems like that would abuse the battery with high charging rates.


	


    The battery is subject to no more stresses than

    situations where you've jump started your car

    because the headlights were left on. Would the

    battery last longer had it never been subjected

    to the deep discharge event? Arguably yes . . . but

    by so small a value as to be difficult to measure

    and totally insignificant to your operational perceptions.

    But it's not an undue stress on the ship's accessories.

    They are all qualified to perform to nameplate ratings

    when the airplane was awarded a type certificate.

 	  Quote: 	
		  Perhaps testing by monitoring voltage and time, 30 min. with a 

conservative volts cutoff(12.0?), whichever comes first might be 

safer, at least for a first try.


	


    So what does the cutoff of 12.0 volts tell you?

    This experiment is not unlike a test in which

    the whole class gets A's. Warm fuzzies abound but

    you acquire no quantitative data on class knowledge.

    The ideal test is just rigorous enough that nobody

    gets 100%. You'll then have a top-to-bottom measure

    of both individual and aggregate knowledge.



    The total depletion test for measuring the total

    contained energy is still the simplest and most

    accurate means by which we can evaluate a battery's

    ability to perform to design goals.



        Bob . . .



         ---------------------------------------

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

         ---------------------------------------

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Oct 08, 2009 9:32 am Post subject: Battery capacity testing

At 09:11 PM 10/5/2009, you wrote:

 	  Quote: 	
		  




	


   <snip>



 	  Quote: 	
		  What all this doesn't tell me is the health of the battery on an ongoing

basis.  I'd think there should be a better way to test this than

repeatedly failing the alternator in flight.


	


   If you want to use test equipment on the ground,

   the simplest and least expensive system I've seen

   looks like this:



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



   Adjust the number and size of lamps to product an

   initial discharge current in the same neighborhood

   as your anticipated alternator-out loads. This

   obviously doesn't go to the 85%-replacement-benchmark.

   Instead, it gives you a rough handle on performance

   to your endurance goals.



   Of course, you've already discovered that knowing

   battery capacity is not terribly useful if you

   don't have timely notification of alternator

   failure. Sounds like you've got a handle on it.

        Bob . . .



         ---------------------------------------

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

         ---------------------------------------

mrspudandcompany(at)veriz
Guest

Posted: Thu Oct 08, 2009 9:48 am Post subject: Battery capacity testing

 	  Quote: 	
		  

Caution.........Unless it is a very early M20F, the gear and 

possibly the flaps are electrically operated. I would not recommend 

running the battery low enough to force lowering the gear by the 

emergency extension. Seems like this would be an issue for all 

retractables that use electric power for gear operation.


	


    I suggested that such testing be accomplished

    under very low risk conditions at altitude.

    As soon as the alternator is back on line, there

    will be enough snort to operate the devices you

    mentioned just from the alternator's output . . .

    and a few minutes later, the battery will have

    stored up enough to operate flaps and/or gear.



    If your battery is in really good shape and still

    above 11.0 volts when 20-20 minutes out, it's probably

    a good idea to terminate the experiment and pay

    attention to pilot business. Conducted with prudence,

    this is a low-priority, low-risk experiment that

    will produce a very accurate assessment of your

    battery's ability to perform to YOUR design goals.

 	  Quote: 	
		  Or are you suggesting staying airborne while you reactivate the 

alternator field and giving it some time to recharge the battery? 

Seems like that would abuse the battery with high charging rates.


	


    The battery is subject to no more stresses than

    situations where you've jump started your car

    because the headlights were left on. Would the

    battery last longer had it never been subjected

    to the deep discharge event? Arguably yes . . . but

    by so small a value as to be difficult to measure

    and totally insignificant to your operational perceptions.

    But it's not an undue stress on the ship's accessories.

    They are all qualified to perform to nameplate ratings

    when the airplane was awarded a type certificate.

 	  Quote: 	
		  Perhaps testing by monitoring voltage and time, 30 min. with a 

conservative volts cutoff(12.0?), whichever comes first might be 

safer, at least for a first try.


	


    So what does the cutoff of 12.0 volts tell you?

    This experiment is not unlike a test in which

    the whole class gets A's. Warm fuzzies abound but

    you acquire no quantitative data on class knowledge.

    The ideal test is just rigorous enough that nobody

    gets 100%. You'll then have a top-to-bottom measure

    of both individual and aggregate knowledge.



    The total depletion test for measuring the total

    contained energy is still the simplest and most

    accurate means by which we can evaluate a battery's

    ability to perform to design goals.



        Bob . . .



         One further **** CAUTION ****  Be very careful doing this test on

your "ALL ELECTRIC AIRPLANE" (ONE HAVING BATTERY OPERATED ELECTRONIC

IGNITION) You may, unintentionally, end up in a glider.



Roger

winmail.dat

Description:

Download

Filename:

winmail.dat

Filesize:

4.93 KB

Downloaded:

446 Time(s)

Kellym

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

Posted: Thu Oct 08, 2009 7:13 pm Post subject: Battery capacity testing

For safety you need to know the minimum excitation voltage for your 

specific alternator. Otherwise you could easily drop the battery voltage 

to a point where turning on the alternator field would get you exactly 

zero output. IIRC for some of the older alternators that value isn't 

much below 11.0.



Robert L. Nuckolls, III wrote:



 	  Quote: 	
		      So what does the cutoff of 12.0 volts tell you?

    This experiment is not unlike a test in which

    the whole class gets A's. Warm fuzzies abound but

    you acquire no quantitative data on class knowledge.

    The ideal test is just rigorous enough that nobody

    gets 100%. You'll then have a top-to-bottom measure

    of both individual and aggregate knowledge.

 

    The total depletion test for measuring the total

    contained energy is still the simplest and most

    accurate means by which we can evaluate a battery's

    ability to perform to design goals.

 

 

 

        Bob . . .

 

         ---------------------------------------

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

         ---------------------------------------

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

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Oct 08, 2009 8:16 pm Post subject: Battery capacity testing

At 10:10 PM 10/8/2009, you wrote:

 	  Quote: 	
		  



For safety you need to know the minimum excitation voltage for your 

specific alternator. Otherwise you could easily drop the battery 

voltage to a point where turning on the alternator field would get 

you exactly zero output. IIRC for some of the older alternators that 

value isn't much below 11.0.


	


   Not true. All the externally regulated alternators

   for which I've designed regulators will come on line

   with less than 1 volt of b-terminal voltage. Everything

   else will light up with 2 volts. Some alternators

   spun at over 10KRPM on the front of a Lycoming will

   self-excite. The gear driven 100A machines on Barons

   and Bonanzas will also self-excite.



   If you can get the battery contactor to close (about

   5 volts) then your alternator will come on line.

        Bob . . .



         ---------------------------------------

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

         ---------------------------------------

bicyclop(at)pacbell.net
Guest

Posted: Tue Oct 13, 2009 8:40 am Post subject: Battery capacity testing

Howdy,



I recently subjected the Concord RG-25XC in our RV to an unscheduled 

deep discharge test by way of leaving the E-buss switch on for a couple 

of days on the ramp at West Yellowstone. We jump started the airplane 

with a car, but as soon as the cables were removed, there was nothing on 

the panel. Apparently the battery was so dead that the alternator didn't 

kick in. I failed to notice if the alternator was running with the 

jumper cables connected, but I think it must have been. All the normal 

lights and gages were working prior to disconnection.



We called National Aircraft Parts Association and had them send over a 

"snowmobile battery", a Yaesu 18ah sized like a PC680 and that got us 

going. We hauled the dead Concorde RG-25XC home and I charged it up. I 

did a capacity check on it with a West Mountain Radio CBA II tester down 

to 10.5 volts, just as I do at annual, and it did pretty well. It 

produced 28 ampere hours at a 4amp draw. Not bad for a 24AH battery! 

When tested at the most recent annual inspection, it put out just over 

30, so it may be slightly degraded, but still very good. We only need 

about 16AH to be able to keep the electronic ignition and some of the 

more important bits of avionics working 'till we run out of gas, so this 

battery still has a ways to go before replacement. I'll save the 18AH 

Yaesu for other uses.



Pax,



Ed Holyoke

 	  Quote: 	
		      The battery is subject to no more stresses than

    situations where you've jump started your car

    because the headlights were left on. Would the

    battery last longer had it never been subjected

    to the deep discharge event? Arguably yes . . . but

    by so small a value as to be difficult to measure

    and totally insignificant to your operational perceptions.

    But it's not an undue stress on the ship's accessories.

    They are all qualified to perform to nameplate ratings

    when the airplane was awarded a type certificate.

rhdudley1(at)bellsouth.ne
Guest

Posted: Tue Oct 13, 2009 9:43 am Post subject: Battery Capacity Testing

For what it is worth, here are my battery endurance procedure  experiences. 

For the first and second annual condition inspections of my RV-6A, I decided  to follow the procedure of replacing my 17/18 AH RG battery rather than do an  endurance check. The battery had cost only $50 and I treated it as  expendable. 

Meanwhile, after the second condition inspection, I conducted experiments on  the replaced battery. Based on measured current draw of the avionics and  instruments that I considered necessary in the event of an alternator failure I  used automobile lights in parallel to simulate a load equivalent to the expected  current drain.. I confirmed the current drawn with that load. Then I monitored  the voltage and the time until the battery reached 11 volts. It turned out that  with a current of about 9 amps, I had 1.5 hours endurance on a battery that had  been used for a year. This pretty much agreed with the published endurance  curves for that battery. 

For the third condition inspection, I decided to test the year-old battery in  place in the aircraft. To accomplish this, I switched on the "endurance" bus,  turned on the avionics and instruments that I considered essential after  alternator failure. I then monitored voltage, the avionics and time. The result  was similar to the earlier simulation with the auto lamps: the avionics went out  at about 1.5 hours.  

Since this test was over in an hour and a half, only a voltmeter and clock  were needed to gather data and the battery was re-charged in a reasonable time  via my external power jack. This convinced me that the battery could be used  until the next condition inspection. 

Should anyone wonder during the second year about the battery endurance, the  test could be conducted at any time with the expenditure of a couple of  hours. 

Regards, 

Richard Dudley 

 

   [quote][b]

trigo(at)mail.telepac.pt
Guest

Posted: Tue Oct 13, 2009 10:52 am Post subject: Battery Capacity Testing

Perhaps a dumb question about a small detail, but to conduct these capacity tests, how did you measure the time, were you one and a half hours looking at the voltmeter to see when it reached the 11V?  

   

Carlos  

   

           

  

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

 Sent: terça-feira, 13 de Outubro de 2009 18:36

 To: aeroelectric-list(at)matronics.com

 Subject: Re:Battery Capacity Testing  

  

     

For what it is worth, here are my battery endurance procedure experiences.  

For the first and second annual condition inspections of my RV-6A, I decided to follow the procedure of replacing my 17/18 AH RG battery rather than do an endurance check. The battery had cost only $50 and I treated it as expendable.  

Meanwhile, after the second condition inspection, I conducted experiments on the replaced battery. Based on measured current draw of the avionics and instruments that I considered necessary in the event of an alternator failure I used automobile lights in parallel to simulate a load equivalent to the expected current drain.. I confirmed the current drawn with that load. Then I monitored the voltage and the time until the battery reached 11 volts. It turned out that with a current of about 9 amps, I had 1.5 hours endurance on a battery that had been used for a year. This pretty much agreed with the published endurance curves for that battery.  

For the third condition inspection, I decided to test the year-old battery in place in the aircraft. To accomplish this, I switched on the "endurance" bus, turned on the avionics and instruments that I considered essential after alternator failure. I then monitored voltage, the avionics and time. The result was similar to the earlier simulation with the auto lamps: the avionics went out at about 1.5 hours.   

Since this test was over in an hour and a half, only a voltmeter and clock were needed to gather data and the battery was re-charged in a reasonable time via my external power jack. This convinced me that the battery could be used until the next condition inspection.  

Should anyone wonder during the second year about the battery endurance, the test could be conducted at any time with the expenditure of a couple of hours.  

Regards,  

Richard Dudley  

   

   	  Quote: 	
		    http://www.matronics.com/Navigator?AeroElectric-List 	
0 	  Quote: 	
		   	
1 	  Quote: 	
		   	
2 	  Quote: 	
		   	
3 	  Quote: 	
		   	
4 	  Quote: 	
		   	
5 	  Quote: 	
		   	
6 	  Quote: 	
		   	
7 	  Quote: 	
		   	
8 	  Quote: 	
		   	
9

  

       [quote][b]

rhdudley1(at)bellsouth.ne
Guest

Posted: Tue Oct 13, 2009 12:27 pm Post subject: Battery Capacity Testing

Hi Carlos,

  

 The short answer is: yes. I used a stop watch  function on my wristwatch. In the first capacity tests with the dummy load of  auto lamps, I checked the voltage at convenient intervals like 10 minutes until  it approched 11 volts because I was unsure what to expect. I even plotted the  data. When it started to change more rapidly I checked more often. From fully  charged, around 12.7 volts to near 11 volts, the change is very slow. Near 11  volts, the decline is quite rapid. 

  

 After I knew better what to expect, during the  actual tests in the plane in the hangar, I just checked the voltage periodically  and noted when the avionics failed. It was part of my condition inspection tests  so, I had other things to do on the plane.

  

 There are plenty of fancier automated ways to test  without personally monitoring. (Bob Nuckolls has published a timer that will  count until the battery voltage drops to a predetermined  voltage.)   However, I felt that I could "squander" an hour and a half  once a year looking at a voltmeter and my watch, and even multitasking with  other tasks I had in the hangar.

  

 Regards,

  

 Richard

 [quote]   ---

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Oct 13, 2009 12:33 pm Post subject: Battery capacity testing

Ed and Richard,



Good job gentlemen! A fine thinker and craftsman of repeatable

experiments once opined:



   "When you can measure what you are speaking about, and express

    it in numbers, you know something about it; but when you cannot

    measure it, when you cannot express it in numbers, your knowledge

    is of a meagre and unsatisfactory kind; it may be the beginning

    of knowledge, but you have scarcely in your thoughts advanced

    to the state of Science."  -Lord Kelvin-

        Bob . . .



         ---------------------------------------

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

         ---------------------------------------

Display posts from previous:

	Matronics Email Lists Forum Index -> AeroElectric-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum