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:
On 22 Dec 2006 17:16:00 -0800, "Boothbay" 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.