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Posted by George E. Cawthon on December 24, 2006, 1:26 am
Buy a $3 digital tester from Harbor Freight and
you won't need to worry about being in the middle
of the scale and you won't need to worry about
polarity (it will tell you). The lowest scale on
many testers is in the 20-25V range anyway.
JGolan wrote:
> I am surprised nobody else mentioned this but you should also choose a
> scale on the meter that will get your reading about center of the
> scale. i.e. if you where testing a battery where you expected about 1.2
> volts you should be using a scale that is about 0-2.5 volts. Analog
> meters are most accurate in the center of the scale.
>
> mm wrote:
>>
>> What the others have said.
>>
>>> I bought a radio shack multitester to check my batteries, primarily my
>>> laptop batteries. First on my old dead battery of Toshiba laptop, they
>>> had a positive and negative mark shown..so it was easy to check it out
>>> with the tester. But I bought it to check my Dell battery that lasted 1
>>> year to the day of the end of my warranty. Fortunately, i did get a
>>> refurbished one in time. Disappointed that it only lasted a year and I
>>> had only used it a total of maybe 10 hours with the battery on my last
>>> vacation...
>> That's why I don't like things that run on batteries. I'm 59 and when
>> I grew up, anything other than a flashlight that required batteries
>> was a luxury. I still feel that way, although I have a few more
>> things than I used to that use batteries.
>>
>>> 10 hours in 1 year and poof it went. The battery does not
>>> have a pos and neg shown like the toshiba one..so I cannot test it that
>>> way.
>> One of the purposes of the meter is to identify + and -. Hold it on
>> one and tap it on the other to see whih way the needle moves. If it
>> moves to the left, reverse the leads.
>>
>>> In the meantime, I was trying to check some AA and AAA batteries
>>> that I had and was able to understand on how to test them..but I do not
>>> know how to interpret the readings I used the ACV side with it set at
>>> 15. I really don't know what does numbers mean. The manual is a joke,
>>> at least for those of us that have no experience. The line moved a
>>> little to the right where it seem to end a couple of notches on that ac
>>> 15v scale. It read the same for the new battery as well, so what is it
>>> telling me that its a 1.5v battery? How does one know if the battery is
>>> weak or whatever? Does anyone know of a web site that can tell me what
>>> those readings represent? I did a search in google but nothing came to
>>> what I was hoping for.
>> We went over this in high school chemistry (which was almost as high
>> level as my college chem oourse) and I'm sad to say that I can't
>> reproduce the numbers, but I saw them and they made sense. That is, g
>> the arithmetic shows that it's the nature of chemical reactions that
>> the voltage stays rather high until the battery is almost fully
>> discharged. So even moderate decreases in voltage represent major
>> loss of charge in most cases. They are right that different kinds of
>> batteries are different in details, but all share this. For a
>> flashlight battery it has to be 80% discharged before the voltage
>> drops to 80% of original. Or maybe 90% and 90%. But like someone
>> said, the voltage might be 90%, but it doesn't have the capacity to
>> put out the amount of current you still need.
>>
>> When you have doubts if it is the battery or the device, try a good
>> battery and see if it works better.
>
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