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What does a battery tester measure?

R

Roy

Jan 1, 1970
0
It's a tiny D'Arsonval Movement meter that measures Bad or Good and a
mark for Low for batteries power...
It works with the voltage in the cells you test, since you place it
between + & - post of the battery., just about anything under 1vdc will
be in the red zone.........

Roy Q.T. ~ US/NCU ~ E.E. Technician
[have tools, will travel]
 
P

Palindrome

Jan 1, 1970
0
Just said:
I have an inexpensive Radio Shack battery tester. This one ...
http://rsk.imageg.net/graphics/product_images/pRS1C-2265632w345.jpg
(except that the needle rests at the bottom of the red - dead zone until
a battery is inserted.)

What does a device like this measure? Volts? Or something else?

The key thing is what it is not - a simple voltmeter measuring the
off-load voltage produced by the cell.

These testers have a built-in load resistor and give an indication of
the voltage that the cell will produce when powering equipment.

Some testers (not this one) draw a great deal of current when used -
testing too often and for too long can substantially reduce battery life!

Radio Shack do have a web page that discusses testing batteries:

http://support.radioshack.com/support_tutorials/batteries/batgd-B08.htm

Which only shows why you shouldn't go to Radio Shack for technical advice ;)
 
R

Roy

Jan 1, 1970
0
Hi Sue ` as usual you're right...I don't think he read that RS link page
on batteries or he wouldn't have had to ask }:

http://support.radioshack.com/support_tutorials/batteries/batgd-B08.htm

I doubt he bought it there at all};
I have one just like it that gets stuck when a fresh battery is tested
and I have to tap it to get it to rest again };) a nice lady
exhibitionist or is it exhibitor};)well., I got it @ a battery expo in a
trade show.
[they're pretty handy testing cups full of stashed battries]

Roy Q.T. ~ US/NCU ~ E.E. Technician
[have tools, will travel]
 
J

Just A Guy

Jan 1, 1970
0
Roy said
I don´t think he read that RS
link page on batteries or
he wouldn´t have had to ask

I did not, but I have now read it, and it did not help. My goal is a
better understanding of the mysterious world around me, with the hope
that through a more "accurate" model of reality, I will be better
equipped to predict and control my environment.

Or, in more practical terms, for about 2 years I have owned a Kodak
digital camera. In reviews of this camera in sites such as Amazon.com,
owners often complain about the difficulty of finding batteries which
will make this camera work. I've been using a variety of different
brands of NiMH batteries. Lately, some batteries which worked fine
before will not now operate the camera, although all these batteries
grade similarly in the RS battery tester, and all will operate an FM
radio.

So I'm trying to figure out what's going on. What is it about this
camera that is so fussy about batteries? Why are these batteries
starting to lose their uumph? Is there a different sort of meter that
will more accurately predict whether a battery will work my camera? Why
do they all test good in the RS tester?
I doubt he bought it there at all

Doubt not; I did.
 
P

Palindrome

Jan 1, 1970
0
Just said:
Roy said

I did not, but I have now read it, and it did not help. My goal is a
better understanding of the mysterious world around me, with the hope
that through a more "accurate" model of reality, I will be better
equipped to predict and control my environment.

Or, in more practical terms, for about 2 years I have owned a Kodak
digital camera. In reviews of this camera in sites such as Amazon.com,
owners often complain about the difficulty of finding batteries which
will make this camera work. I've been using a variety of different
brands of NiMH batteries. Lately, some batteries which worked fine
before will not now operate the camera, although all these batteries
grade similarly in the RS battery tester, and all will operate an FM
radio.

So I'm trying to figure out what's going on. What is it about this
camera that is so fussy about batteries? Why are these batteries
starting to lose their uumph? Is there a different sort of meter that
will more accurately predict whether a battery will work my camera? Why
do they all test good in the RS tester?

The problem is that digital cameras tend to both draw a high current and
need a high voltage from the battery, at the same time. Your tester
almost certainly is not drawing a high enough current to give a
realistic reading of what the voltage will drop to when in the camera.

Different cells, from different manufacturers, of different ages, at
different temperatures, of different mAH rating, will perform
differently under the camera load - but will look to be doing much the
same on the tester as it is at the moment.

The answer is to modify the tester so that it does draw the same
current, when testing, as the camera does when running. Which will mean
adding an additional resistor between the two test terminals of the tester.

I happen to have a new camera here with new freshly recharged batteries,
(intended as a gift for someone). So I measured the current to see what
sort of current is drawn. This one, with 4 cells, draws 0.5A.

The nearest preferred value resistor as a dummy load to test individual
cells would be 2.2 ohms in my case. You would probably need something
similar, but you could measure the current that your camera takes and
adjust the value to suit, if necessary.

A modified tester should show you a significant difference between the
readings of "good" and "bad" batteries, for your purpose.

Note that the "bad" batteries will still be good enough for many, many
applications that aren't as demanding in current and voltage as a
digital camera.
 
A

Anthony Guzzi

Jan 1, 1970
0
Just said:
Roy said

I did not, but I have now read it, and it did not help. My goal is a
better understanding of the mysterious world around me, with the hope
that through a more "accurate" model of reality, I will be better
equipped to predict and control my environment.

Or, in more practical terms, for about 2 years I have owned a Kodak
digital camera. In reviews of this camera in sites such as Amazon.com,
owners often complain about the difficulty of finding batteries which
will make this camera work. I've been using a variety of different
brands of NiMH batteries. Lately, some batteries which worked fine
before will not now operate the camera, although all these batteries
grade similarly in the RS battery tester, and all will operate an FM
radio.

So I'm trying to figure out what's going on. What is it about this
camera that is so fussy about batteries? Why are these batteries
starting to lose their uumph? Is there a different sort of meter that
will more accurately predict whether a battery will work my camera? Why
do they all test good in the RS tester?



If you find out, please let me know. I'm in a similar situation with my
DC 240.
 
R

Roy

Jan 1, 1970
0
Sun, Jun 1, 2008, 6:39pm (EDT+4)
From: [email protected] (Palindrome)
Just A Guy wrote:
Roy said
I don´t think he read that RS
link page on batteries or
he wouldn´t have had to ask

I did not, but I have now read it, and it did not help. My goal is a
better understanding of the mysterious world around me, with the hope
that through a more "accurate" model of reality, I will be better
equipped to predict and control my environment.
Or, in more practical terms, for about 2 years I have owned a Kodak
digital camera. In reviews of this camera in sites such as Amazon.com,
owners often complain about the difficulty of finding batteries which
will make this camera work. I've been using a variety of different
brands of NiMH batteries. Lately, some batteries which worked fine
before will not now operate the camera, although all these batteries
grade similarly in the RS battery tester, and all will operate an FM
radio.
So I'm trying to figure out what's going on. What is it about this
camera that is so fussy about batteries? Why are these batteries
starting to lose their uumph? Is there a different sort of meter that
will more accurately predict whether a battery will work my camera? Why
do they all test good in the RS tester?

The problem is that digital cameras tend to both draw a high current and
need a high voltage from the battery, at the same time. Your tester
almost certainly is not drawing a high enough current to give a
realistic reading of what the voltage will drop to when in the camera.
Different cells, from different manufacturers, of different ages, at
different temperatures, of different mAH rating, will perform
differently under the camera load - but will look to be doing much the
same on the tester as it is at the moment.
The answer is to modify the tester so that it does draw the same
current, when testing, as the camera does when running. Which will mean
adding an additional resistor between the two test terminals of the
tester.
I happen to have a new camera here with new freshly recharged batteries,
(intended as a gift for someone). So I measured the current to see what
sort of current is drawn. This one, with 4 cells, draws 0.5A.
The nearest preferred value resistor as a dummy load to test individual
cells would be 2.2 ohms in my case. You would probably need something
similar, but you could measure the current that your camera takes and
adjust the value to suit, if necessary.
A modified tester should show you a significant difference between the
readings of "good" and "bad" batteries, for your purpose.
Note that the "bad" batteries will still be good enough for many, many
applications that aren't as demanding in current and voltage as a
digital camera.
--
Sue

You're not kidding - There are special batteries for digital
applications - alkaline and other gp batteries fail mimicking dead after
a few repeated clicks on the battery powered device [cam etc.]

most batteries repond well to instantaneous repetitous demand on low
charge devices where the demand is greater & more dependent on voltage
than on current flow [as in the glow of a grain of wheat lightbulb] -
but with digital devices the demands is both for current & voltage this
can cause severe drainage to the cells charge almost instantaneously.,
leaving the lcd screen on will only affect the chemicalization process
more that which maintains the charge turns null....

I always wondered if I [one] could get radioactive waste and make good
barreries from it but got stopped by how to turn metal waste into
paste}:)

The batteries for digital devices/cameras are made up so that the cells
don't drain on instantaneous repeatitive demand...
one thought is the individual cells are probably just stacked closer
together inside the battery and electrons flow through easier....plus,
"the stuff" inside has to be more lucid:) as with lithium ...

Roy Q.T. ~ US/NCU ~ E.E. Technician
[have tools, will travel]
 
D

Dave Martindale

Jan 1, 1970
0
hifi-tek said:
Or, in more practical terms, for about 2 years I have owned a Kodak
digital camera. In reviews of this camera in sites such as Amazon.com,
owners often complain about the difficulty of finding batteries which
will make this camera work. I've been using a variety of different
brands of NiMH batteries. Lately, some batteries which worked fine
before will not now operate the camera, although all these batteries
grade similarly in the RS battery tester, and all will operate an FM
radio.

The problem may be that the batteries have developed too much internal
resistance. A digital camera may draw several *amps* from the batteries
while recharging the flash after a flash photo, and older cameras were
somewhat demanding on batteries even when the flash was not fired.
If there's too much internal resistance, the battery voltage will drop
during flash recharge and the camera will shut down. This is the same
reason that alkaline batteries tend not to work well in older digital
cameras.

Your FM radio receiver probably draws a few thousandths of an amp, so
internal resistance doesn't matter. Your battery tester will draw
somewhat more, maybe 50 or 100 mA, but that's still not enough to
simulate the load a camera places on the batteries.

Dave
 
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