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VOM Troubles

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Dennis Johnson

Joined: 10 Jan 2006
Posts: 89
Location: N. Calif.

Posted: Sun Aug 16, 2009 2:25 pm Post subject: VOM Troubles

I have a Fluke model 87 digital VOM (Volt-Ohm-Milliammeter) that has just started discharging the internal 9 volt battery in less than a month while it is turned OFF.  I've had this meter for 15 years and used it throughout building my airplane, as well as various hobbies before that, so I guess I got my money's worth out of it, but I'm puzzled.



Using another meter, I measured about 10 microamps current out of the Fluke's internal 9 volt transistor radio battery while it's turned OFF.  If a 9 volt transistor radio battery holds 0.5 amp-hours, then with 10 microamps, the battery should last 50,000 hours.  But the last two batteries lasted about a month each.  They test good before I put them in and have an expiration date of 2013.



First, is my arithmetic correct?  I think a milliamp is 0.001 amps and a microamp is 0.000001 amps.  I think a 10 microamp current through a half amp-hour battery would take 50,000 hours to deplete the battery.  



Second, did I read my digital VOM correctly?  Using a nice German BBC VOM, set on the 2 milliamp scale, it reads .009.  Using a cheap Harbor Freight digital VOM, set on the 200 microamp scale, it reads 09.5.



You can see that something is wrong, either with my math or the way I'm reading the scale on the VOMs.  Or maybe the Duracell fairies are sneaking in and sucking all the juice out of my batteries?



I talked to Fluke customer support and he said there was no published spec on the current draw from the battery while it was turned off and couldn't say if mine was bad or not.  My model 87 isn't supported anymore and he wanted me to buy the new version.



Any ideas?



Dennis Johnson

Lancair Legacy, 330 flight hours

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Aug 17, 2009 6:09 am Post subject: VOM Troubles

At 05:25 PM 8/16/2009, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "Dennis Johnson" <pinetownd(at)volcano.net>



 I have a Fluke model 87 digital VOM (Volt-Ohm-Milliammeter) that has just started discharging the internal 9 volt battery in less than a month while it is turned OFF.  I've had this meter for 15 years and used it throughout building my airplane, as well as various hobbies before that, so I guess I got my money's worth out of it, but I'm puzzled.

 	


    Great instrument. I've had one since they came

    on the market.



  	  Quote: 	
		  Using another meter, I measured about 10 microamps current out of the Fluke's internal 9 volt transistor radio battery while it's turned OFF.  If a 9 volt transistor radio battery holds 0.5 amp-hours, then with 10 microamps, the battery should last 50,000 hours.  But the last two batteries lasted about a month each.  They test good before I put them in and have an expiration date of 2013. 	


 [img]cid:.0[/img]



    A Duracell 9v has published performance data as shown

    above. The smallest discharge curve is for 2 ma

    so with a end of life voltage of say 7 volts, yes

    the device should deliver 500 mAh of service at

    2 mA and MORE at still smaller drains. The internal

    resistance of the battery becomes less significant

    as current demands drop . . .



  	  Quote: 	
		  First, is my arithmetic correct?  I think a milliamp is 0.001 amps and a microamp is 0.000001 amps.  I think a 10 microamp current through a half amp-hour battery would take 50,000 hours to deplete the battery. 	


    Yup, that's about right.

  	  Quote: 	
		    



 Second, did I read my digital VOM correctly?  Using a nice German BBC VOM, set on the 2 milliamp scale, it reads .009.  Using a cheap Harbor Freight digital VOM, set on the 200 microamp scale, it reads 09.5. 	


    The interpretation of your observations seems

    correct.



 

  	  Quote: 	
		  You can see that something is wrong, either with my math or the way I'm reading the scale on the VOMs.  Or maybe the Duracell fairies are sneaking in and sucking all the juice out of my batteries?



 I talked to Fluke customer support and he said there was no published spec on the current draw from the battery while it was turned off and couldn't say if mine was bad or not.  My model 87 isn't supported anymore and he wanted me to buy the new version. 	


     My model 87 is 100 miles away right now

     but I'll be back in that shop tomorrow or

     Wednesday. I'll duplicate your experiment

     so we can compare results. In the mean time,

     perhaps someone else here on the List has

     a model 87 Fluke and can do their own

     investigation.



 

        Bob . . .



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

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

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

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david.nelson(at)pobox.com
Guest

Posted: Mon Aug 17, 2009 9:12 am Post subject: VOM Troubles

I've a Fluke 87 so I'll check it out this PM and report back.



 	 /\/elson



~~  Lately my memory seems to be like a steel trap .... without any spring.  ~~



On Mon, 17 Aug 2009, Robert L. Nuckolls, III wrote:



 	  Quote: 	
		   At 05:25 PM 8/16/2009, you wrote:

       



       I have a Fluke model 87 digital VOM (Volt-Ohm-Milliammeter) that has just started discharging the internal 9 volt battery in less than a month while it is turned OFF.  I've had this

       meter for 15 years and used it throughout building my airplane, as well as various hobbies before that, so I guess I got my money's worth out of it, but I'm puzzled.

 



   Great instrument. I've had one since they came

    on the market.



       Using another meter, I measured about 10 microamps current out of the Fluke's internal 9 volt transistor radio battery while it's turned OFF.  If a 9 volt transistor radio battery

       holds 0.5 amp-hours, then with 10 microamps, the battery should last 50,000 hours.  But the last two batteries lasted about a month each.  They test good before I put them in and

       have an expiration date of 2013.

 

 

 Emacs!



    A Duracell 9v has published performance data as shown

    above. The smallest discharge curve is for 2 ma

    so with a end of life voltage of say 7 volts, yes

    the device should deliver 500 mAh of service at

    2 mA and MORE at still smaller drains. The internal

    resistance of the battery becomes less significant

    as current demands drop . . .



       First, is my arithmetic correct?  I think a milliamp is 0.001 amps and a microamp is 0.000001 amps.  I think a 10 microamp current through a half amp-hour battery would take 50,000

       hours to deplete the battery.

 



    Yup, that's about right.

 



       Second, did I read my digital VOM correctly?  Using a nice German BBC VOM, set on the 2 milliamp scale, it reads .009.  Using a cheap Harbor Freight digital VOM, set on the 200

       microamp scale, it reads 09.5.

 



    The interpretation of your observations seems

    correct.

 



       You can see that something is wrong, either with my math or the way I'm reading the scale on the VOMs.  Or maybe the Duracell fairies are sneaking in and sucking all the juice out

       of my batteries?



       I talked to Fluke customer support and he said there was no published spec on the current draw from the battery while it was turned off and couldn't say if mine was bad or not.  My

       model 87 isn't supported anymore and he wanted me to buy the new version.

 



     My model 87 is 100 miles away right now

     but I'll be back in that shop tomorrow or

     Wednesday. I'll duplicate your experiment

     so we can compare results. In the mean time,

     perhaps someone else here on the List has

     a model 87 Fluke and can do their own

     investigation.



        Bob . . .



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

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

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

simon(at)synchdes.com
Guest

Posted: Mon Aug 17, 2009 4:51 pm Post subject: VOM Troubles

Dennis, your math is correct.  You will get 50,000 hrs out of a 0.5 Amp-Hr

battery at 10 uA.  I took my trusty Fluke 87 into work today to have its

battery current measured.  It was 7.9 uA.  There is something wrong with

your meter.  I'm guessing one of the components has failed or there is FOD

somewhere causing low resistance.



If it is FOD, possibly you can solve it by cleaning the PWB or the rotary

switch.  This particular problem may be exacerbated by the auto-turn off

feature, which is controlled by a microcontroller.  The reason is because a

FOD can cause a small amount of current to flow in the right place and tell

the microcontroller to turn the whole meter on and keep it on.  It may be

worth it to blow clean both the PWB and the rotary switch and then retest

it.



I've had this meter since the 1980s, and I'd hate to see it go.  It's a

really good meter!



Good luck.



Simon Ramirez

Copyright 2009

--

Dennis Johnson

Joined: 10 Jan 2006
Posts: 89
Location: N. Calif.

Posted: Mon Aug 17, 2009 6:00 pm Post subject: Re: VOM Troubles

Thanks to Bob for confirming that my calculations weren't off by a few decimal points.  Thanks to Simon for measuring the current draw of his Fluke 87. 



Simon's current draw, when turned off, was 7.9 micro amps.  Mine was 9.5 micro amps.  So it seems like my meter is probably okay.  I'll try blowing out dust and I'll go with another new 9 volt battery and hope the gremlins leave me alone.  Could be a bad batch of 9 volt batteries?  Still a puzzle.



Thanks, guys!



Dennis Johnson

ulflyer(at)verizon.net
Guest

Posted: Mon Aug 17, 2009 8:25 pm Post subject: VOM Troubles

Hey Guys,

Can't say about the batteries you have but the Duracells are not the 

battery they used to be.  You used to be able to put them into a 

piece of equipment and not have to worry about them leaking, were 

great for meters and cameras, not so any more.  If I had to put my 

finger on it I would say it started when they came out with their 

more expensive (longer life) ultra's.  Ever wonder what's inside a 

Duracell battery, see the link below.

http://www.extremetech.com/article2/0,3973,1155268,00.asp



Sounds like your going to need a new Du-witcher - cost $150 bucks - 

that's the thing the test leads plug into to.



Note, if you have a Duracell (alkaline) battery that has leaked, 

clean it up best you can using white vinegar & Q--Tips for the tight 

spots.  Alkaline is a base - when it leaks it is quite aggressive and 

can eat things up in a short time.  It can be neutralized with a acid 

which vinegar supplies.



jerb





At 07:00 PM 8/17/2009, you wrote:

 	  Quote: 	
		  

<pinetownd(at)volcano.net>



Thanks to Bob for confirming that my calculations weren't off by a 

few decimal points.  Thanks to Simon for measuring the current draw 

of his Fluke 87.



Simon's current draw, when turned off, was 7.9 micro amps.  Mine was 

9.5 micro amps.  So it seems like my meter is probably okay.  I'll 

try blowing out dust and I'll go with another new 9 volt battery and 

hope the gremlins leave me alone.  Could be a bad batch of 9 volt 

batteries?  Still a puzzle.



Thanks, guys!



Dennis Johnson

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Aug 18, 2009 8:33 am Post subject: VOM Troubles

At 11:22 PM 8/17/2009, you wrote:

 	  Quote: 	
		  



Hey Guys,

Can't say about the batteries you have but the Duracells are not the 

battery they used to be.  You used to be able to put them into a 

piece of equipment and not have to worry about them leaking . . .


	


    I've not experienced a leaking incident with

    flashlight cells in years. I did loose a digital

    caliper last month because an alkaline button cell

    leaked . . . but it was a case where the tool was

    stored for a long time with a discharged cell. Our

    battery powered devices are working tools that generally

    don't get stored for long periods of time with dead

    cells.



. . . they were great for meters and cameras, not so any more.



    I've not detected any 'changes' in these products

    tendencies to leak in our regular change-out working

    environment. Has anyone else on the list experienced

    a messy event with their alkaline cells of any brand?

        Bob . . .



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

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

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

jindoguy(at)gmail.com
Guest

Posted: Tue Aug 18, 2009 9:08 am Post subject: VOM Troubles

Bob, When I had my LSA inspected I found the Duracells in the ELT (dated to 2010) had leaked all over the inside. Later that summer I had a maglite also taken out of commission by some Duracells. In both cases they were D size. That was last year. Except for the new ELT in which I have to, I don't buy Duracell anymore.  Going by a study you did a few years back, I buy the chicom batteries at Dollar General. Can't tell you anything about electrical characteristics, but I do know that we've never had one of any size leak.



 Rick Girard



On Tue, Aug 18, 2009 at 8:45 AM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

 [quote]--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)>

  

 At 11:22 PM 8/17/2009, you wrote:

  	  Quote: 	
		   --> AeroElectric-List message posted by: jerb <ulflyer(at)verizon.net (ulflyer(at)verizon.net)>

 

 Hey Guys,

 Can't say about the batteries you have but the Duracells are not the battery they used to be.  You used to be able to put them into a piece of equipment and not have to worry about them leaking . . .

 	
 

    I've not experienced a leaking incident with

    flashlight cells in years. I did loose a digital

    caliper last month because an alkaline button cell

    leaked . . . but it was a case where the tool was

    stored for a long time with a discharged cell. Our

    battery powered devices are working tools that generally

    don't get stored for long periods of time with dead

    cells.

 

 . . . they were great for meters and cameras, not so any more.

 

    I've not detected any 'changes' in these products

    tendencies to leak in our regular change-out working

    environment. Has anyone else on the list experienced

    a messy event with their alkaline cells of any brand?

 

 

        Bob . . .

 

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

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

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

 

 

 

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

 ===========

 http://forums.matronics.com

 ===========

 le, List Admin.

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

 ===========

 

 

 

 [b]

trumanst(at)neitel.net
Guest

Posted: Tue Aug 18, 2009 3:36 pm Post subject: VOM Troubles

Bob,I had the Duracell D's in my ETL leak also.

I had the Batterys.com AA cells leak in my Lowrance 2000C. Had Duracell AA cells swell in my Mag Lite. 

Had one hell-of-a time shaking it out. Did get it out though. A bit of a mess to clean up, but no apparent damage to any of my devices.



 Kevin Boddicker

Tri Q 200 N7868B  140.6 hours

Luana, IA.

 



On Aug 18, 2009, at 8:45 AM, Robert L. Nuckolls, III wrote:

[quote]--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)>

At 11:22 PM 8/17/2009, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: jerb <ulflyer(at)verizon.net (ulflyer(at)verizon.net)>

Hey Guys,

Can't say about the batteries you have but the Duracells are not the battery they used to be.  You used to be able to put them into a piece of equipment and not have to worry about them leaking . . .

 	




   I've not experienced a leaking incident with

   flashlight cells in years. I did loose a digital

   caliper last month because an alkaline button cell

   leaked . . . but it was a case where the tool was

   stored for a long time with a discharged cell. Our

   battery powered devices are working tools that generally

   don't get stored for long periods of time with dead

   cells.

. . . they were great for meters and cameras, not so any more.

   I've not detected any 'changes' in these products

   tendencies to leak in our regular change-out working

   environment. Has anyone else on the list experienced

   a messy event with their alkaline cells of any brand?





       Bob . . .

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

       ( . . .  a long habit of not thinking   )

       ( a thing wrong, gives it a superficial )

       ( appearance of being right . . .       )

       (                                       )

       (                  -Thomas Paine 1776-  )

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

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Thank you for your generous support!

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 [b]

raymondj(at)frontiernet.n
Guest

Posted: Thu Aug 20, 2009 9:48 am Post subject: VOM Troubles

Bob,



	I've had several Duracell batteries leak in the last couple of years. 

They were C & D cells in Maglight flashlights.  They were kept in 

vehicles, which resulted in them being cold soaked to temps of -20 deg 

f.  I attributed their failures to the cold exposure, but that was pure 

conjecture. They were installed in the fall and found to have leaked in 

the spring.



Raymond Julian

Kettle River, MN



"Hope for the best, but prepare for the worst"



do not archive



Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   

 <nuckolls.bob(at)aeroelectric.com>

 

 At 11:22 PM 8/17/2009, you wrote:

> 

>

> Hey Guys,

> Can't say about the batteries you have but the Duracells are not the 

> battery they used to be.  You used to be able to put them into a piece 

> of equipment and not have to worry about them leaking . . .

 

    I've not experienced a leaking incident with

    flashlight cells in years. I did loose a digital

    caliper last month because an alkaline button cell

    leaked . . . but it was a case where the tool was

    stored for a long time with a discharged cell. Our

    battery powered devices are working tools that generally

    don't get stored for long periods of time with dead

    cells.

 

 . . . they were great for meters and cameras, not so any more.

 

    I've not detected any 'changes' in these products

    tendencies to leak in our regular change-out working

    environment. Has anyone else on the list experienced

    a messy event with their alkaline cells of any brand?

 

 

        Bob . . .

 

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

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

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

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